Category: Battery Technology. 46v ebike battery

Range Anxiety? Be Prepared (and Stop Worrying)

Want to take a long trip with an ebike? Just want to proof yourself against running out of juice on your commute? Here are a variety of solutions.

I’ve put rather a lot of effort into proofing myself against running out of battery juice. In all the years I have been using an ebike as a daily driver – almost always for utility rather than for recreation – I have never run out of battery power. Even when I’ve forgotten to charge before a ride (more on that below).

There Are Solutions

Lets explore some range-extension options. Hopefully you’ll come across something here you hadn’t thought of and can take advantage of.

Use a Big Battery

This is the most obvious one. If you don’t want to run out of gas, put in a big gas tank. This is not a new idea. Nowadays when a gearhead hears about a Corvette Z06, a super fast, light and powerful version of that car comes to mind… but back in 1963, if your option code was RPO Z06, that meant you had the “big tank” Corvette… with a freaking 36 gallon gas tank to minimize refueling stops during races. Or Cannonball runs.

If you are doing a DIY ebike conversion, unless you have specific weight goals, you typically want to fit the biggest battery you can afford. Same goes for a manufactured ebike. If it has a larger battery option… you want that. Whether you can take advantage of an option will boil down to the size of your wallet. An XL-sized battery will also let you preserve your battery by charging it to 80% or 90%, but thanks to it being oversized you still have enough in the tank to go wherever you please.

I am all about big batteries on the bikes I build. The Great Pumpkin has a 31 amp-hour, 52 volt custom triangle pack. The Lizzard King has a 32ah/52v brick hiding under its floor. That ties for biggest pack in the fleet with 2Fat – now a recreational bike, it needs big power to run through remote stretches of beach without inland access. That bike has two parallel’d 16ah/52v packs joined together to make a single 32ah battery.

Bigger is better only up to a point. Big batteries equal big weight. So there’s a limit to what you can and should get away with. You can’t go this big on normal neighborhood ebikes, nor should you.

With all that said, going big on a battery can also save your bacon when you do something like forget to charge your battery… there’s enough extra capacity to eke out a ride home rather than having to figure out a way to sleep over at the office.

Bring Along a Spare Battery

This is my least favorite solution, but it may work for you. If you have a battery, buy another one just like it and toss it into a backpack or pannier. Swap it in when needed. This is probably most likely going to appeal to folks with a manufactured ebike and thus no other options. Unfortunately with a solution like this, you can’t get anywhere near as much out of two batteries as you would be able to for a big single one, or for two joined together in parallel (you can to only partially drain each of your packs, hence the loss in capacity). But you suffer the same weight penalty.

Sidebar: Don’t parallel batteries together unless you know EXACTLY what you are doing. Running packs in parallel increases the potential for danger dramatically, and should only be messed with by folks with the experience to know how to mitigate those increased risks.

Onboard Charging (Permanent Mount)

I have written up my experiences with using Mean Well power supplies as CCCV ‘Smart chargers’, and mentioned they are fanless and weatherproof. This and the fact they have mounting tabs means they can be mounted permanently. Assuming the bike is large enough to have a brick bolted on without anyone really noticing. That can mean cargo bikes and any bike with a front rack – the charger works great as a rack deck. And on the front, you don’t really miss the fact you can’t put a rack trunk on.

Pictured above on the left: The Big Fat Dummy and its 185w/3a charger gassing up at the park. The charger is bolted onto the lower deck, up front on the rack. On the right: The Great Pumpkin‘s 320w charger on the front rack is good for 5 amps.

The 480w monster now on the front rack of 2Fat is good for a whopping 8 amps. Its supersized, as when I need a recharge on that bike I am in the middle of nowhere and facing darkness, fog … and may need to negotiate with an unpleasantly high tide if I dawdle.

Onboard Charging (Carried in a Bag)

You don’t always want to be lugging a charger around; nor do you always have a place to bolt one on. I have both 185w and 320w portables that I bring along occasionally on bikes that don’t have a permanent charger mount. For instance, I didn’t want to add a heat-generating charger to the largely enclosed basement battery box on The Lizzard King. So I carry the 320w unit you see below when circumstances warrant (not the shoe. Thats just there for size comparison). Being able to pump in 5a into any battery is going to add a whole lot of range if you plug in while having lunch.

Speaking of open outlets, where are they best found? Here in the USA I have really good luck with public parks. Oftentimes a picnic canopy will have a working power outlet. You can also stop at a roadside cafe, shop or gas station and ask the owner if you can plug in while you are there visiting. This works best if you are stopping somewhere for lunch and will be there for awhile. I’ve also found plugs attached to the outside of restroom buildings at state parks.

Obviously, this approach works best on regular routes where you can determine in advance what is available. Keep your eyes open, scope out your options and file that information away for the time when you need to use it.

Don’t Be Such a Pig

This next one is obvious… or is it? Its a technique I have used and it gets the job done so here goes:

Use less power, as in dial back the assist. My Bullitt with its Great Big Battery was about 3 miles into a 16 mile Saturday morning Costco run when I realized I had forgotten to charge it after work on Friday. Its 52v/14S battery reads 58v when its full, and was already down to 52v when I realized my mistake. Not only would I be blowing my morning turning around and going back home, it would be hours before that battery was charged. I decided to just go for it. So I reduced my assist to the minimum and continued. When I returned home with a cartful of groceries stuffed into my cargo box and panniers, I was down into the mid 40’s, voltage-wise – and more than a little worn out.

But I made it. I wouldn’t have if I had not gone overboard with the size of the battery.

After this I made sure I carried a charger with me on these trips. There is a park midway on the journey with a publicly available power plug. I can plug in, sack out and catch a nap next to a water fountain and be on my way. Late… but I’ll have beaten the system.

Charge at Public (J1772) EV Charging Stations

Yes really. It may be difficult to find an open plain vanilla AC power outlet that you can use… but nowadays electric vehicle (as in automobile) charging stations are popping up all over the place.

If you do not live in the USA, you will want to find a different adapter than what I am describing below (from what I hear non-USA charging stations in the EU are much more likely to have an ordinary, separate outlet available for public use).

But in the Land of the Free, this may be the only obviously available power plug you can get hold of. I’m seeing them increasingly in parks and ordinary store parking lots. Likely they are also springing up at the more refined campsites and national parks.

This is an option that hasn’t been available until recently, and is still not widely known or even understood. Above is a picture of the adapter I have. It plugs into a USA-standard J1772 EV charger plug and terminates in a female NEMA 5-20 plug on the other side. NEMA 5-20 plugs are also compatible with NEMA 5-15 plugs. Folks in the USA know of the 5-15 as your garden variety 3-prong grounded electrical plug. Using this adapter, you now have a bridge directly from a 240v EV car charger to a plug that you can connect your charger into.

Fzzzzzzzz… BOOM!

Thats what could happen if you just plug in without making sure your charger can handle 240 volts of current versus the usual 120.

Here’s the thing: Many ebike chargers are manufactured to run on global power grid voltage. In the USA, we use 120v. Much of the rest of the world uses a lot more volts. 240v in particular. So if you are manufacturing chargers and want to sell them everywhere, you make one that can handle the various voltages right out of the box, so you only have to make one model. However, you can’t count on this feature being there. So check first.

How can you tell? Look at the fine print on the label. The really tiny print that you never read. In the case of the Mean Wells I use, its written clearly in big letters, since they are meant for commercial use and nobody cares if they look pretty.

Yup it’ll handle 240 volts, alright. Since I have also made chargers for relatives who use them on their ebikes in the EU, I know they work just fine on the higher EU voltages.

But thats me. YOU have to figure this out for yourself on your own charger. You won’t know until you go look.

So Much For The Good News…

Here comes the bad news: These adapters are expensive. I have seen them selling for as much as 200. Oddly enough, after some googling I found a seller only an hour or so down the road from me who seems to have the lowest sale price on the web. I paid 85 for mine. Thats still a lot. Lets hope the price is only going down as these types of units become more common.

Or better yet, lets hope that EV charging stations in the USA start commonly having normal AC plugs available.

Whether that happens or not, you should be able to do one or more of the things above, and turn range anxiety into something you used to have … but don’t anymore.

A Backpack Ebike Battery… Are You Insane.

If all I did was write internet posts, I’d still hate this idea. But circumstances made me try one. I knew almost immediately how wrong I had been.

Brace yourself, because, if you haven’t already tried it, and you are like most people, you probably think this is the worst idea, ever. I was one of those people. Then I built a bike that simply had to use a backpack battery as its power source. I held my nose, gritted my teeth and just did it. I dreaded the result right up until I rode it for the first time.

Look at the two pics below. Where’s the battery? Nowhere. Nowhere in the picture, at least. I was wearing it. In the image at right, I have used subtle visual cues to highlight the silicone-insulated XT90 connector I plug into.

By the way, that is a Cyc X1 Pro Gen 1 motor. The little bag houses a BAC800 controller that reached 60 amps of continuous output before I chickened out and lifted.

What problem are we solving?

A backpack battery should obviously not be your first choice, so why do one at all? When doing a DIY ebike build, there are some donors that just don’t have space for a battery.

Where the hell am I going to fit a battery on this bike? I will deliberately NOT answer that question here.

In an earlier draft of this post, I wrote up all the different things I thought of or actually tried, and abandoned because they sucked for one reason or another.

But that is going off into the weeds as this discussion is about backpack batteries, not build or donor choices. So lets table all that talk and just stipulate: We have this bike that we have to work with. we looked at alternatives (remember… I hated this idea at the time), we are left with one choice:

The battery has to be in a backpack

Once I accepted the fact I was stuck doing a backpack, all that was left were materials and ergonomic/mechanical choices. i.e. just make it and do it right.

Pack Choice

If you listen to the experts on the internet (thats a joke in case you missed it), whenever the subject comes up you hear all about how a battery on the back of a rider is a bomb just waiting to go off. There is some truth to this. Flying off the bike and landing on your back on sharp rocks is a really bad thing made a whole lot worse if a li-ion battery is your crash bumper.

There’s also a lot of talk about how the world will end if you put your battery weight up on your back, but we’ll get to that one later.

The solution for safety is to use a hardshell pack of some sort, of the kind you see used on sport motorcycles. I picked a 20L Boblbee GTX from Point65.

Nope, it sure as hell isn’t cheap (I paid about 200 for mine which is way less than they are now), but remember that unexploded bomb thing? Its for real and a hardshell pack solves that problem. It also provides you with spinal protection in case of a crash. And you also get something that addresses another negative the villagers are shouting about: A pack like this form fits your spine, hugs your body and never shifts – not even a little.

I suppose if you had to, you could use a soft pack and then stick your battery into a 30 cal or 50 cal ammo can. Drill a hole in a corner for the power cable exit and it would work, but that can is going to be a lot of weight to carry. Still, if you want a cheap, safe solution that uses a conventional pack… thats it. I’m sure you will figure something out on the shifting thing. I know I have packs that don’t shift. Much.

Really though… this is a problem you need to throw money at to properly solve. In my case I spent about half of retail by finding a vendor closing out an old model and blowing them out at a big discount.

Battery placement inside the pack

You do not want the battery bouncing around freely inside that hardshell pack. Each battery and backpack combo is different, but the core of the solution is to stabilize it with dense, closed-cell padding. I didn’t say wrap it tightly in foam so it overheats (put down that pitchfork). However, part of a Smart DIY plan is to use cells that can take a murderous flogging without heating up in the first place. I used the old standby Samsung 25R cell for mine.

For my pack, I add in a little judicious padding. Then sprinkle some tool bags in there (so no little bags on the bike). Job done. Its not moving around.

Figure out the wiring / connection

This is the tricky part because if you get this wrong and stay aware of the cable, you will hate your ride. First off, I used a short 8ga XT90S extension directly off the main battery output. I pretty much do this on every battery connection on any bike so, when connecting and disconnecting the pack, I’m visiting the wear and tear on a cheap replacement connector and not a live cable soldered into the pack. I also use a pair of XT60 pigtails to make a similar extension cable for the charge connector. Same idea. I’ve had my bacon saved doing this and the experience of just being able to throw away and replace a cheapie extension made this a go-to for me on everything.

Next comes a long length of true 10ga power cord, made into a long XT90S extension cord. This is what will go from the battery to the motor and its several feet long. How long exactly? I measured out enough to exit the pack, run down my back, down thru my legs and still be long enough to never tug if I am standing on the pedals and bouncing around at the same time.

OK… great… what if I’m sitting down? A cable long enough to stand up with is going to be all kinds of awkward when doing what you do most: Sitting. I spent a fair amount of time trying to figure out what to do about this. A lot of others have done some sort of elastic bungie contraption. I tried that and felt it needed too much strain to extend, and carried a risk of pulling apart the connection at the motor. I needed something that reliably retracted my cable and extended it without much resistance.

And here’s the solution: The Key-Bak Super48 HD. This is literally the direct descendant of that chromed steel extendo keyring thing that every janitor in the United States has on his belt. Except they aren’t chromed steel anymore.

The model I bought has a 48″ extension length, with their lightest 8 oz pull and a kevlar cable. Its so lightweight, it doesn’t impart the same feel of indestructability that the old steel pucks had, but I have been using it since mid-2019 and so far it shows no sign of wear. You can see from the Amazon link above that there are other models of varying lengths and pull weights. You can even get one with a steel cable. Since I’ve been using mine, I can say its 48″ extension is plenty, and the light 8 oz pull makes its operation completely unnoticeable.

How do you make the Key-Bak work?

What you need is a ball attached to your power cable. The cable threads through the key ring and stops at the point where the ball – which is bigger than the ring – is reached. You place the ball at a point down your back and to the side, so there’s more than enough cable slack to let you stand on the pedals, but not so much it gets in your way.

When you stand up the keyring lets the cable extend until the ball stops it. When you sit back down, it retracts back up behind you. Simple and effective. You never have excess cable down around your legs getting in the way. If you need more, the light 8 oz pull lets it happen without your even noticing its there. In fact, you really don’t know its there at all because its placed where you can’t see it, behind you and to the side. Out of sight and out of mind.

Once I spent some time figuring out the cable length needed to do the job right, and where the ball needed to be, I built and positioned the ball as follows:

  • A strip of leftover silicone handlebar grip roughly 1.5 inches long. Since I have used Wolf Tooth Fat Paw grips and ESI Extra Chunky XXL grips with my Jones bars on various bikes over the years, I have leftovers from grips that were cut off.
  • Plenty of silicone X-Treme sealing tape.
  • The silicone grip segment – since it was already sliced off a set of handlebars – already had a slit in it to let it slip over the cord. Wrapping silicone in silicone tape sticks instantly, and doing so – with overwrap onto the adjacent power cord, tightly affixes it so its not moving, ever.
  • Silicone tape fuses permanently to itself and isn’t going to unravel.
category, battery, technology, ebike

The above is just one way to do this. In my case with spare stuff laying around in my garage.

Whats With The Cargo Net?

With a 20ah battery, two small tool bags (one on each side of the pack) and an electric pump, the interior of the backpack is pretty much full. I found some hooks that work well with this pack on Amazon, and applied them to the pack and the net. Now I have the ability to stuff something onto the exterior of the pack. Usually that is my veteran Condor Summit Zero and maybe a small, flat pouch for wallet and phone if I can’t stuff them into the handlebar bag.

What is it like when you ride it?

I wasn’t expecting a good experience. The idea of being tethered to the bike and having a power cord running down off my back… I hated everything about that. Boy was I ever wrong, and if I hadn’t built the solution and gotten on the bike and tried it, I’d still be just as wrong. This is something you have to experience to fully understand and appreciate.

The Good.

You are still tethered to the bike. But the Smart setup mitigates this so thoroughly its unnoticeable when you ride and requires very little extra effort to deal with.

Not having the battery weight on the bike makes it behave… like a bike. Internet experts will jump up and down and point to the higher center of gravity that comes from putting the pack on your back. But reality is that without the weight of the battery, smashing thru a rock garden or challenging singletrack is like doing it on an unpowered bike. Since in singletrack you usually only use (or want) power when going uphill, that means your ride everywhere else is exactly like you want it: Old school analog. Your suspension acts like it should… but with a rider who’s eaten too many cheeseburgers.

Having the battery on your back means you can shift its weight from side to side just as you already do with your body. See the above point, because that one and this one together completely undo the whole ‘center of gravity’ argument, and put the backpack setup in the ‘superior’ category when it comes to all-around performance. If you are wearing a 10 lb backpack… so what? You spent the money to buy a pack with a completely form-fitting back panel, that attaches firmly to you so its an extension of your body. No shifting of any kind whatsoever. You did that, right? Bought the really good pack? Cuz if you swiped your kid brother’s lunch pack or figured out some other way to cheap out… you’re screwed. Proper packs are not just ones that shield and pad the battery. They shouldn’t fidget.

Holy crap I totally forgot about that cable! I thought that was going to suck so hard, and I don’t even know its there! Thats you after your first ride. My first config ran the cable around my side and did not go thru my legs. I was concerned (and rightly so) the cable could flop away from my side and hang up on a bush. So I took the plunge and ran it between my legs like the experienced builders say I should. Sure enough it works perfectly.

We have addressed the safety/crash issue by using a hardshell pack, with some dense foam around it but not smothering it (and used a battery cell that doesn’t heat up under extreme load). That makes the battery safer than it ever would be in a ‘traditional’ battery bag.

The Bad.

You are still tethered to the bike. I never said a backpack was the best solution. Its just the only one sometimes. Its not the end of the world if you do it right.

When you stop the bike, you have to disconnect. Its not difficult, but you have to do it so it goes on the list. I keep XT90 safety caps in a little pouch and use them to cover the open connections on the bike and my battery cable. When I mount the bike, I first lower the dropper post all the way. Then I straddle the bike from behind, standing over the rear wheel. I connect the power and, since the seat is so low, I can just step forward and be right over it. I then raise the dropper and I’m on the bike. Dismounting I have some options. I can be standing and reach down, disconnect and just throw my leg over like usual, or do the reverse of the mount from the rear. In practice I’m about 50-50 as the rearward exit is easier but I need to think about it to do it.

And The Ugly

Whats ugly is I used that unoriginal cliche for those pro and con section titles. Lets take a break, sit down with a plate of spaghetti and enjoy the movie!

Quick Release, Easy-Carry Ebike Battery Setup

Parking your ebike outdoors all alone? When shopping, my cargo bikes are locked but out on the street… but the battery goes in with me. Here’s how I do it without people thinking I am carrying a bomb.

Yes You Can Take ‘it’ With You

An ebike used for utility purposes is, by its nature, going to be left out a lot. You go to the store, load up a shopping cart, come back and fill up your saddlebags. You really want all the parts on the bike when you left to still be there. Especially after loading on 50 lbs of cat food, Oreos and diapers.

The most obvious way you keep the bike itself is to use a good locking strategy. I’ll save that for a different discussion. This time I will FOCUS on how I protect the single most-expensive component on any ebike – the battery. Not by locking it up, but by making it so I can do a quick grab and carry it in with me.

By removing that battery, we are making that big heavy ebike into a boat anchor, which we can hope makes it at least a little less attractive to thieves.

Size (and Shape) Matters

What I am describing can be made to work with any shape battery, kept anywhere on your bike. What you see here works best with a squarish, oblong battery. In the pics below I am using a 17.5ah Luna Storm battery, which is pretty big and heavy (in part thanks to its powerful but not-so-energy-dense 25R cells). likely, if you have a similar heat-shrink battery pack like this one, its quite a bit smaller and lighter.

I also keep a Luna Wolf Pack battery like this and do not use its magnetic mount. The battery is easy to quickly get off that mount, but leaving it inside of a bag like I describe here is, overall, easier than stuffing it in every time, taking it back out and so on. For packs like this (Wolf, Shark, Dolphin etc.) you could certainly bring a small pack and put it in/take it out as a part of your routine.

There’s more than one way to skin this cat, so what you see here is just a jumping off point.

Lets Get to It

This is the battery in its bag, just like it would be if I rolled up to the local Costco.

Ignore the charger cable in the front. I took this pic at work in my ebike garage.

If we zip open the bag, we don’t see a battery. We see an inner bag, along with that charger cable extending thru to the rear. The controller cable is in there too just out of sight (look closely and you can see it)

If we look inside the bag, we see the battery charge cable is in fact an extension running from the rear of the interior bag up and out the front. The motor cable – an XT90S connector – also has a short extension between the battery cable and the motor cable. The idea is this: when routinely, frequently detaching and reattaching the cable, if there is any wear its on a cheap, replaceable extension and not a critical, live/hot cable coming directly off the battery.

Disconnect the cables and give a tug to the inner bag. Here its shown halfway out but you will just pull the thing out in one motion.

Annnd here we are. the cables are shown sticking out of the inner bag. You will want to cap those for safety’s sake. I use cheap plugs I got a bagful of on Fleabay for a couple bucks.

And yes… as-is I have had someone ask me “what is that a bomb?” … only half joking and ready to clock me if I make a sudden move. So stuff the wires in the bag so they don’t stick out.

Done! Wires are capped and stuffed into the bag in 5 seconds. The sling strap goes over your shoulder for easy carry. I just lug it to the nearest shopping cart and put it in the bottom rack with my helmet and off I go.


Its a really short list with one item on it.

category, battery, technology, ebike

Hydration Carrier

You see above the Blackhawk S.T.R.I.K.E. carrier in use. Purchase link is here. Yes, the name is a tad ridiculous. But this pack is minimalist and is just durable cloth with no insulation or padding. Its easier to stuff into a confined space. Mine came with a super sturdy velcro sling strap.

Another that is well made (and a tad smaller for a tighter fit is sold by Voodoo Tactical. It comes with thin backpack-style shoulder straps that don’t take up too much space in your triangle bag and are not enormously fiddly when stuffing back in there.

Another one I use (with my Luna Wolf pack) is this government-issue USMC carrier. The link is to a brand new unit. I got mine surplus and cheaper on Fleabay. This pouch has no straps (you can clip on your own from a duffel bag if you like) and it is the opposite of the Blackhawk carrier: Its thick and padded. I can still stuff it into any triangle bag I have despite this. Its great as a protective layer over a battery.

Wrapping It Up

There are lots of ways to do this. How I do it is no big deal. Key takeaway here is to find a method that works for you so you can swiftly grab the battery, go off to your next adventure and then come back and plug right back in again.

Li-Ion Ebike Battery Charge Charts

Whats an 80% charge on a 48v battery? on a 36v? 52v? These charts give answers to questions like these on all common ebike battery voltages.

Remember, ALL numeric charts show ballpark values that may be numerically correct, but no generic chart can match your individual cell characteristics, your pack’s age or its chemistry. Bottom line: imperfect charts like this are still good baseline references. Use these and teach yourself how to read the voltage gauge on your display screen.

Quite some time ago, I produced a series of charge status charts for a variety of common lithium-ion battery voltages. They’ve become a fairly common link to help folks out on various groups who use these battery voltages in their ebikes.

I built them using Google Sheets, so they are not web pages, which I suppose has kept them from being widely linked in search engine results when people are looking at such things.

Here for the first time are direct links to the charts on a normal web page.

Volt (10S) Battery Charge Chart

The first link is to the lowest voltage: 36v. Generally this is the lowest voltage you will find on a modern, commercial ebike. Note that its called ’36 volt’ but really that is the ‘nominal’ value. A 36v battery is actually fully charged when it is at 42.0 volts.

Volt (13S) Battery Charge Chart

The next common size is 48v. These batteries are fully charged at 54.6 volts.

Volt (14S) Battery Charge Chart

The next battery voltage is 52v and very common. 52v batteries will work on systems designed for 48v, and why is easier to understand when you become aware that a ’48v’ battery really tops out at over 54 volts. A ’52v’ battery tops out at 58.8v, so it essentially lets you use a 48v system for a longer time at higher voltage levels that it is already designed to utilize.

Volt (16S) Battery Charge Chart

With a 100% charge voltage of 67.2 volts, when you have one of these you are getting into high voltage territory

An Ultra Reliable Ebike Battery Charger…

How about a charger – quickly adjustable for voltage and current – that is rated for hundreds of thousands of hours of use before it typically fails?

… Some Assembly Required

Please take note: Mean Well LED power supplies have been used by the DIY ebike community for years. The concept is not new. The weak link here is you and if you screw this up consequences could be profound If you know your way around a crimper, or a soldering iron… great this will be easy. Kid stuff. If not, don’t pick this project as your first learning experience. With that said, here is a complete instruction set on making one of these units.

Why reinvent the wheel here? What benefit could be gained?

Ebike battery chargers tend to be dodgy. The interwebs are filled with stories of frequent flyers whose chargers keep dying. Its either a dead fan that in turn lets the charger heat up and fry, letting the smoke out of the internals (never a good sign) or perhaps the most common: the charger stops cutting off at its cutoff voltage and keeps on charging … with potentially catastrophic results.

So… what is better? You can see that in a popular commercial battery charger: The Grin Satiator. Its so efficient it needs no fan to cool it (or to fail). It is also largely weatherproof and highly reliable. The only demerits it gets from users – which have largely gone away over time – are programming/firmware issues.

Oh and its cost is US300 once you figure in a programming cable, along with a couple of adapters. I bought one. It works perfectly. But with an AWD bike with 2 batteries that I ride every single day and charge both at home and at work, I found convenient charging means walking up and plugging in. Not carrying chargers with me, unloading them, setting them up etc. So 2 batteries x 2 locations = four chargers. 300×4= not happening. And I carry a charger with me in case I get stranded. 300×5=crazy talk.

What to do? Use the same core hardware that gives us the 300 charger but without the fancy user interface. That could cost as little as around 40 if we are lucky, and 90 if we are not (or we buy a more expensive option). We won’t have a fancy display screen or onboard memory, but it will still be adjustable with a screwdriver.

I have worked with three different models that can serve my purposes. Remember that volts x amps = watts and this will be important when figuring out what to set your charger for:


  • Discontinued. See next entry below for replacement
  • Available regularly on Amazon for about US55
  • Rated to 150 watts
  • Rated as adjustable from 40 to 56v but actually adjusts from 39v to 58.1v
  • Usable as an 83% to 100% charger for a 36v battery
  • 80% to 100% for 48v battery
  • 80% to 96% for a 52v battery
  • Minimum amperage selectable is about 1a
  • Lower wattage rating means it must be set to lower amperage on 52v batteries (2.5a max for a 52v battery)
  • Constant Current Constant Voltage (CCCV) output (i.e. ‘Smart charging’: Ramps power down slowly and precisely as it approaches target voltage.
  • Designed for LED lighting and ‘moving sign’ lighting applications
  • IP65 rated for indoor and outdoor use.
  • Usable at EU or USA voltages.
  • Mean Time Between Failure (MTBF): 303,700 hours. Yes, really.
  • Spec Sheet Here


  • They come up on Ebay for as little as 20 on occasion, or full retail at a reputable seller is 48.
  • Rated to 120 watts
  • Rated as adjustable from 38 to 46v
  • Usable as an 80% to 100% charger for a 36v battery
  • Minimum amperage spec is 1.4a but likely goes lower.
  • 2.8a current is max for 100% 36v battery charge (117.6w) which is just under the safe limit for typical 36v charger pin plugs.
  • Constant Current Constant Voltage (CCCV) output (i.e. ‘Smart charging’: Ramps power down slowly and precisely as it approaches target voltage.
  • Designed for LED lighting and ‘moving sign’ lighting applications
  • IP65 rated for indoor and outdoor use.
  • Usable at EU or USA voltages.
  • Mean Time Between Failure (MTBF): 559,500 hours. No thats not a misprint.
  • Spec Sheet Here
  • If you can safely exceed 2.8a of current, go for the 150w model.


  • Available often on ebay for about US40. Normally on sale in the 49-75 range.
  • Rated to 185 watts.
  • Rated as adjustable from 49 to 58v. Actually adjusts from 48.3v to 60.0v
  • Usable as an 80% to 100% charger for 48v and 52v batteries. Not usable on 36v systems
  • Typically this is a good 3a charger for 52v batteries. 3 amps x 58.8 volts = 176.4 watts.
  • Adjustable to very low current (about 0.85 amps) for trickle charging.
  • Constant Current Constant Voltage (CCCV) output (i.e. ‘Smart charging’: Ramps power down slowly and precisely as it approaches target voltage.
  • Mean Time Between Failure (MTBF): 192,200 hours, or almost 22 years of continuous use.
  • Designed for LED lighting and street lighting applications
  • IP65 rated for indoor, outdoor and wet/hazardous locations
  • Usable at EU or USA voltages
  • Spec Sheet Here


  • 320 watt capacity. Big and heavy.
  • Street Price around 90. Often available on EBay for around 50, even down to as little as 25 each if someone is selling off a pair of them wired together as Zero e-motorcycle chargers.
  • Essentially same specs as the HLG-185H-54A but is instead rated for 320 watts
  • Current can only dial down to about 2.0 amps. But the high wattage rating means it can be dialed UP to make it a 5 amp charger (only aftermarket battery plugs like XT60 or Andersons are able to safely handle this current level). 5 amps x 58.8 volts = 294 watts.
  • MTBF: 157,100 hours (just under 18 years of continuous use)
  • The 320H units I have bought on the aftermarket were originally wired together in pairs in series and used as onboard 115v Zero Motorcycle chargers
  • Spec Sheet Here


  • New addition to the product line since this thread was originally created. I purchased one in November 2021 for a project.
  • 165 street price
  • 480 watt capacity. 8 amps x 58.0 volts = 464 watts
  • Usable as an 80% to 100% charger for 48v batteries. 80% to 95% on 52v batteries. Not usable on 36v systems
  • Minimum 4.4a rated current rate (max 8.9a) means not safe for anything but an aftermarket battery connector (XT60 Yes, barrel connector No)
  • Voltage adjustment range rated to 45.9-56.7v. My unit is 41.9-58.1v
  • Current adjustment range rated to 4.4-8.9a. My unit is 3.5-9.9a
  • Constant Current Constant Voltage (CCCV) output (i.e. ‘Smart charging’: Ramps power down slowly and precisely as it approaches target voltage.
  • A charger exclusively for a big aftermarket battery that can safely take 4-9 amps.
  • Not for novices
  • MTBF 95,300 hours (almost 11 years of continuous use)
  • Weight is over 6 lbs. Not typically something you want to be carrying around.
  • Spec Sheet Here


  • New addition to the product line since this thread was originally created
  • 170 street price
  • 600 watt capacity
  • Minimum 5.6a rated current rate (max 11.2a) means not safe for anything but an aftermarket battery connector (XT60 Yes, barrel connector No).
  • Supports a dimmer function via bare /- leads (on the ‘AB’ model variant).
  • Multiple power outputs enable charging multiple batteries at once, so maybe it makes some sense for multi-bike households.
  • Not for novices – know what you are doing insofar as batteries, chargers, charge capacities and battery chemistry are concerned.
  • MTBF 76,900 hours (a mere 8.7 years of continuous use)
  • If you thought the 480H was big wait until you see this one.
  • Spec Sheet Here
  • Garden hose spray (or heavy rain) – Yes
  • Ocean waves – Maybe
  • Bottom of fish tank – Hell no

Myself, my bikes have 52v batteries. I do use a couple of CLGs at work for my charging station there but only because I hadn’t found the HLG-185’s yet. The HLG-185’s are ideal chargers as they can charge at levels safe for the Sondors battery plugs (3a max) and can handle any voltage asked of them for a 48v or 52v system. If you have an aftermarket battery that does not use the pin plug as do the Sondors batteries, then you almost certainly have an Anderson Powerpole, an XT60 or an XLR connector. Those plugs can handle the higher amperage the 320 is capable of delivering. I use a 320 as a travel-with charger under the theory that if I am stuck somewhere I want to grab as much charge as I can, as fast as I can. But a 185 is perfectly capable of being a 3a charger and weighs probably half what the 320 does.

So… enough details already. Lets make a charger!

Here’s what we need:

  • A Mean Well power supply. The process is identical for all models.
  • A pigtail’d grounded electrical plug. They are sold on Amazon typically as replacements for corded drills and similar power tools. NOTE: I am using a USA standard plug, but these units are made to accept worldwide voltage/current so just go to your local hardware store and choose your local version of a pigtail’d, grounded power cord if you live outside the USA. Oh, and read the spec sheet to confirm what I just said applies in your country.
  • A digital watt meter to tell us what we are outputting to the bike. For almost all of my chargers I use 15 inline watt meters. This is optional but very desirable.
  • An interface from the charger to the battery. I will use an XT60 as the direct connection, which is what a lot of aftermarket batteries use. You can then plug just about any adapter into that for your Sondors or whatever else you have. Note in the picture above, bottom center just to the left of the little adjustment screwdriver we will keep with the charger, that there is a pin plug adapter for use with Sondors batteries. That one came from Luna Cycles.

A Note on Battery/Watt Meters

Here’s the short version: They suck. Or more accurately they are oftentimes off by a bit, and there is no way to calibrate them. Its not uncommon to see a battery meter accurate to within 2%. That sounds ok unless you are charging to 58.8v, which could be 59.98v with a 2% error and that is very, very bad. So you want to take a multimeter or similar known safe benchmark (in a pinch the reading on your LCD screen will work once you have disconnected any charger from it) and use it to learn where your chosen meter is in terms of its accuracy. I do this and then I take a labelmaker and make a label telling me how much a meter is or – actual voltage.

So for example, if my target voltage for a 52v battery is an 80% charge of 55.4v, and my watt meter is reading 0.50v higher than it should be, then I create a label that says

UPDATE:This link is to one of many cheap Chinese watt meters. The last two I have used, purchased across a span of 4 months, exhibited a new and consistent behavior: Plug them in and they are WAY high, by like 1.2v. But sit and watch the meter over a span of about 5-10 minutes and you will see it slowly auto-correct itself down to a steady reading. This steady reading will still be off by a bit but not so bad… these last two meters were both off by only about 0.20v… so I recommend these as your best option – and recognize they have a calibration stage at startup that you need to wait out.

So now, we have our parts in hand and its time to assemble them. In order the steps are

Step 1

Attach the pigtail’d cord to the input side of the Mean Well unit. For the USA plug and the Hanvex drill cord I have been using, the wire sequence is green (cord wire) to green (charger wire) for ground, black (cord) to brown (charger) for AC and white (cord) to blue (charger) for AC-. Note that the wire colors are noted on the charger left side, but as ACL and ACN. DO NOT SCREW THIS UP. These are international standard designations and colors which as usual the U.S. does not follow. If you want to check my work, start googling. Myself, I use marine heat shrink butt end connectors to connect the wires. I also use rather expensive electrician’s-grade crimping pliers. There is a big difference between proper crimping pliers and … well, pliers. Use the right tools for the job. After I crimp, I heat shrink the connectors, add heat shrink around each individual wire and then do a heat shrink around that entire assembly. How you do it is up to you (i.e. soldering or whatever). Remember that this is mains power you are fooling with here so get this right.

Step 2

Attach a battery side plug. In this case I am using a male XT60 which both works for my aftermarket batteries that have female XT60 charge plugs, and my bottle batteries where I use my XT60-to-pin-plug adapter. Same procedure as in Step 1 although a little simpler as there are only two wires. Note that some of these charger units do not use red and black wires. If you are not familiar with what the colors mean, the casing on the unit specifically tells you which wire is which (V and V-).

When you are done, you will have something looking like this:

Step 3

OPTIONAL – attach an inline watt meter to the output side of the Mean Well unit. This is your power display. I call this step optional because you could just calibrate your charger output once and not use a meter to monitor progress (easy enough to turn on the bike display during charging, which will hurt nothing). Myself personally, even though meters are pesky insofar as getting them calibrated, I prefer to have a real time progress monitor I need only glance at.NOTE: Source side of the meter gets connected to the charger. Load side goes to the battery.

Step 4

OPTIONAL – make an extended output cord. Essentially one big extension cord on the battery side. You’ll know real fast if you’d like to have one of those as whatever you made doesn’t reach. You could just hardwire this to your output lead on the charger. But then you are stuck with that length alone. I prefer to make a cable as I have no problem using a couple of 12 AWG XT60 pigtail ends to make a dedicated extension.

Step 5

Connect an interface to your battery. For a Sondors, this is a pin plug connector. For many batteries the generic standard is a male XT60 connector. You can either buy a direct-connect bottle battery adapter (see link) or connect a male XT60 pigtail and then buy an XT60 Female-to-bottle adapter. Doing it the latter way makes your charger able to connect to any battery (if you have another battery with say XLR connectors you can make an XT60-to-XLR adapter via a couple of pigtails). You just swap in the adapter you need. In this case I am picturing a Luna-sourced XT60 female to pin plug adapter. A different source for the same thing is in the parts list below

Step 6

Go out and buy a little Phillips head screwdriver. This tool will live with your charger forever so you should buy a new one unless you have an extra already. Its a must-have for the next step. Also required if you plan on changing your settings (lets say you want to charge 80% one day and 100% the next).

If you have performed all of the above steps, you now have a parts pile that looks like this (well sort of, the meter and the charger have already been labelled with calibrations but just pretend we haven’t done that yet):

Step 7

Dial in your output voltage. Once you have connected an AC plug, and a battery side connector AND connected the inline watt meter, you simply have to plug the new charger into the wall. Amps will read zero and volts will read whatever the unit is currently set for. See the little rubber whatsits that are capping the voltage (Vo ADJ) and amperage (Lo ADJ) adjustors? Pull those off and stick the screwdriver into the Vo ADJ hole. Twiddle it around gently until you feel it seat into the adjustor. Now turn it first one way, then the other. Watch the voltage readout on your meter. One way goes up, the other down … and the directions are different on my 185’s and 150’s vs. my 320 so you figure out what direction does what yourself with your own unit.

Step 8

Calibrate your meter to reality. Remember what I said above about meters. You need to figure out how far off your meter is from your display. As you can see if you look closely above, this meter is off by 0.50v. Thats a fair bit. The good news is when these types of meters are off, they are consistently off so you just need to know by how much (and if you can find a meter that is consistently accurate tell me. I can’t find one at any price). this is a pain but you only have to do it once.

Step 9

Dial in your output amperage. OK… moment of truth time. You are plugged into the wall. Time to plug into your battery. Maybe you should do this out in a field with a long extension cord. Don’t do it in the baby’s nursery or in Grandma’s bedroom while she’s asleep. Plug the battery in and now watch the meter. The voltage switches to now show the battery state of charge. The amperage comes to life and shows the current level (amps) being fed into the battery.

Once again, like you did with the voltage adjustment, use your screwdriver this time in the Lo ADJ socket and twiddle it until you see the safe amperage rate you safely want to safely run your charger safely at. Did I forget to mention safety? And volts x amps = watts ? Pay attention and get this right. If your meter is off – especially if it is reading lower than actual voltage – you will want to find out by what percentage it is off and adjust your indicated meter amperage less that percentage amount.


  • Your charger does not switch its power feed on and then off like a light switch. Instead, it will slowly ramp down its current delivery level (amperage) as the battery approaches your target voltage. So that means if you plug in a battery that is fully charged or nearly fully charge, you will get a really tiny reading of current going into the battery – and this will give you a false idea of the amperage your charger is set for. Because of this, when performing calibrations you must have a battery that is at least a couple of volts low. At least. If you are charging to 54v (100% charge on a 48v battery) then plug in a battery at no higher than, say, 50v state of charge.

If you are using a pin plug, NO MATTER WHAT make sure this value does not exceed 3 amps. The plug can’t safely take more. Again, remember that volts x amps = watts. So if your 185w HLG-185 is feeding the max of 3.45 amps, that means at 58.8v it will be sending 203 watts which exceeds its 185w rating and thats VERY bad. Here again. Use your brain and don’t screw up. Best to leave a safety margin. For example I have one of these set to a ‘full’ charge of 58.3v and 3.0 amps. 175 watts.

Step 10

Add a carrying case? Your basic MOLLE water bottle bag will fit this all beautifully. the slightly larger Condor bags available on Amazon will do so with a little more fudge room. I got two green ones on sale for 5 and 8 respectively. Sometimes they are more. Happy hunting.In the end what do you have? A charger that you can expect to be reliable literally for years. Not necessarily cheaper, but dependable. If you buy this once you won’t have to buy it again in 6 months or a year… and thats the usual story out there in ebikeland for the more demanding users in the DIY world.

Parts (remember oftentimes you can get these chargers for a lot less on clearance on Fleabay). Especially the HLG-185 which is commonly used in street lights):

Hanvex 18awg 3-prong AC power cord, 6ft, pigtail’d (10.99)

XT60 male and female pigtails (need 5 total if you are using an inline watt meter, extension cable and xt60 lead for battery) (8.99)

Carrying case – MOLLE water bottle pouch


I had the opportunity to make another charger over the weekend for my daughter and son-in-law. They also live in the EU and as such I needed the appropriate plug – the charger will auto-sense the voltage coming in and adjust accordingly. So for those of you folks outside the U.S., here’s what one looks like.

My daughter’s locale uses a 2-prong grounded ‘Schuko’ type plug. One nice thing about using international parts is they conform to the same international specs. So there is none of the translation necessary to pick which wire goes to where. Just match the colors and you are done.

This time I took the time to take pics before and after during assembly. The heat shrink and adhesive on the marine-grade splice connectors make for a very solid connection. There is a trick to doing the best crimping:

  • do it on the very ends
  • don’t crimp so hard you tear deeply into the plastic covering the splice
  • ensure the pointy prong on your crimper faces AWAY from the other wires so if you do overcrimp and tear into the plastic, you won’t expose metal facing the other wires.
  • Use a halfway decent crimper. I think I made this point in the original post but it bears repeating. Use the wrong tool for the job and your results will suck.

There is also a trick to heating the adhesive connectors – First, use a nozzle on your heat gun that narrows the heat exhaust so you can better direct it to a small area. Next, heat the ends that you actually need to shrink up and grip the wire. Stay away from directly heating the metal center. If you do that, any tearing of the plastic over the crimp tends to actually seal itself. If you heat the center, those tears will break open further as the adhesive plastic shrinks from the heat. Its actually pretty easy to do… you just have know to do it… and now you do.

Heat shrink over top of those adhesive connectors and you have a stable, solid connection you need to look for to notice.

Do it again for the XT60 ‘universal’ output connector. Make sure that external heatshrink is plenty long. In this case I made sure I had plenty of exposed wire on the end because I like the flexibility. If I wanted to reinforce it and maintain that flexibility, self-adhesive silicone tape (sticks only to itself; spiral wrap it around the wire) is the perfect solution. The Sondors-compatible bottle connector I chose for this charger had a male plug end on it, so I needed to make another connection using a short female-to-female XT60 extension. It is important to get your genders right on a charger. You do NOT want a male XT60 or male anything else exposed on the battery side as an arc between the terminals is much more likely on a male plug, and that can destroy your battery.

Here’s the whole thing put together with a meter added to the end and the Sondors-compatible 5.5mmx2.1mm barrel connector attached. The meter is showing it is configured for an 80% charge on a 52v battery. After I took this pic I realized I needed to set it up for a 48v battery and changed the voltage on the charger and the label on the meter.

These chargers are sturdy enough and water-resistant enough to mount on your bike as an onboard charger. Here is one bolted onto a front rack. The cords are gathered up in a MOLLE dump pouch attached to the handlebar bag. Just open the flap and pull out the cords.

Introduction: How to Rebuild a BionX E-Bike Lithium-Ion Battery Pack

About: Was a maker before makers became a thing. I have always enjoyed solving problems with my hands. I also enjoy writing. About kmpres »

Hello fellow Makers, Hackers and DIYers!

This instructable will show you how you can replace the lithium-ion cells in a worn-out BionX e-bike battery pack to restore your lost range and even greatly exceed it. It will also show you how you can replace your original equipment charger with a high quality balance charger so you can to get the most from your rebuilt battery.

The CANBus, Rear Rack, 37 Volt, 6.4 Amp-hours, 236.8 Watt-hours battery in my Dahon MuP8 e-bike worked reliably for two years, but soon after the warranty expired the range dropped from 10 miles to maybe 2, even when I did all the pedaling, so the time had come to open it up to see what could be done. Inside I found that BionX had packed forty 1,600 mahr US18650V lithium-ion cells into a cavity that could hold sixty and simply filled the empty space with foam blocks. This presented an interesting opportunity as I soon realized that I could replace the original forty cells with new ones having twice the capacity and add twenty more, which would give me three times the original range while adding only a few more pounds of weight. The trick then, was to figure out how to do it without destroying the battery or breaking the bank.

I found tons of videos on the internet showing how to build e-bike battery packs, but few people have rebuilt a BionX pack due to the unusual nature of their construction. I had also wanted to convert my pack to 48 Volts by using a different control board but that turned out to be more expensive than expected, and since the existing Smart Connect ver 5.2 control board still worked well, if I kept it I could retain all the original BionX functions, which as e-bikes go, are quite extensive. That meant the new pack had to stay at 37 Volts, but I could convert it from 10S4P to 10S6P and increase the number of cells to sixty, thus increasing the pack’s cell count by 50%. To increase the cell capacity I chose to replace them with Panasonic NCR18650B cells which are the same ones used to power the Tesla Model S electric car. They can deliver a sustained 10 amps and have a 3,400 mahr capacity.- more than twice that of the ones they’d replace.- which would add 100% more capacity giving me a total gain of 150%.

I also wanted to charge the pack with a balance charger rather than use my original BionX charger so I could keep better track of my pack’s condition. The BionX 37 Volt charger relies on a low 2 amp charge rate, temperature sensors and some control circuitry to determine the end-of-charge. While this is a perfectly safe method of charging lithium-ion cells under normal conditions, the pack lacks a Battery Management System (BMS) which means that the cells must not lose much of their balanced state in the course of their use. It is still possible for one or more cell groups to become unbalanced as they age which can lead to reduced output and a pack that will no longer charge to its full capacity. It is much better, in my opinion, to use a good quality balance charger as they monitor the voltage of each cell group and automatically balances them to within a few millivolts of each other as the charge progresses. They can also alert you if any cell group under-performs relative to the others and let you make adjustments or intervene if things go awry. But my BionX battery pack didn’t come with a balance port, so I would have to add one.

Please note that I present this instructable to you with an Attribution Non-commercial Share Alike license, which allows you to use it for your own use as long as you don’t attempt to profit from it commercially. However, in addition I must give you a stern warning and disclaimer: This project is NOT for beginners. Please do NOT attempt it if your soldering skills are only “average” as you can easily short the pack if you’re at all sloppy or don’t follow proper safety precautions. People have accidentally caused fires and/or injured themselves with lithium-ion cells so before beginning this project I want you to clearly understand the dangers involved. I am in no way responsible for the use or misuse of the information presented here. What you do with it is entirely up to you and at your own risk.

With that out of the way, let’s begin!

Step 1: Safety Equipment, Tools and Parts

Despite the dangers, there are ways of protecting yourself and reducing the risk of fire. The first, obviously, is to keep a fire extinguisher on hand at all times. Mine is a First Alert ABC dry chemical type available in any hardware store. Next, during construction make sure you use good eye protection, gloves and ventilation, and remember to take off any rings, watches and jewelry beforehand. Finally, you should always charge your battery in a fire-proof box or bag even after your charging routine has proven itself safe and reliable. I use a large, heavy bag called a “HoverCover Fire Resistant Hoverboard Bag” that I bought for 60 off Amazon. It is designed to fully contain a hoverboard fire. A bag like this is very good, cheap fire insurance and could save you from disaster.

I left the original BionX charging circuitry and 4-pin XLR connector intact so I could use the original charger if my balance charger idea didn’t work out, but I’m happy to report that the new charger was so successful I no longer use the old one. I can still, however, use it as a portable spare and might take it with me on some long trips.

For regular charging, however, I highly recommend using a good quality balance charger as it gives you complete control over all ten cell groups, allows you to monitor their charge and discharge voltages, display their internal resistances, change the voltage and current settings and easily track the overall condition of your pack. My charger is an iCharger 4010 Duo that I bought from Progressive RC for 350. Not cheap, but it charges most anything at up to 75 amps and was one of the few I’d found that could balance charge a 10S pack without my having to divide the pack into two parts. It does not come with a DC power supply, however, so be prepared to buy or provide that separately if you purchase one.

To do this upgrade you’ll need 60 new Panasonic NCR18650B cells (or equivalent), which are available from a number of vendors online. Be mindful of the postal regulations if you live overseas as hazmat shipping methods may be required. You could use recycled cells from old laptop batteries but you won’t get the capacity you can with these new cells, and matching their internal resistances over time is problematic at best. You also can’t escape the fact that the older the cells, the more quickly they will deteriorate, and since you don’t know their age to begin with, you may find yourself with a poorly performing pack sooner rather than later. My advice is to spend the money now on high quality new cells so you won’t have to spend it again later.

You’ve probably guessed by now that this is not a cheap project. With new batteries, charger, assorted parts, tools and international shipping I probably spent more than 1,000.- more than even what a new pack would have cost me from BionX. However, my new battery will (hopefully) last twice as long as my old one did and go three times further per charge giving me a much lower cost per mile, and the knowledge I gained by successfully taking one apart and rebuilding it is, to me, priceless. But mistakes can be expensive so be certain you know exactly what you are doing before tackling this project. Also know that this project will very likely void your warranty. I therefore suggest you not attempt it until after your warranty expires so as to not lose your support from BionX, who are generally good about warranty replacements. My warranty had already expired and overseas shipping regulations made my buying a replacement battery difficult and expensive so rebuilding my pack was really the only option I had.

You’ll need these parts:

  • 60 Panasonic NCR18650B cells or equivalent. Do not get cells with built-in protection circuits as those will not fit the enclosure.
  • 1 10S balance charger. e.g. iCharger 3010B or iCharger 4010 Duo.
  • 1 Fire-proof bag or box for charging
  • 1 ABC fire extinguisher
  • 10 feet of 12 AWG super-flex stranded wire, 5ft red, 5ft black
  • 10 feet of 14 AWG super-flex stranded wire, 5ft red, 5ft black
  • 10 feet of 12 conductor, 22 AWG, multi-colored stranded wire
  • 25 feet of 1/4″ flat pre-tinned copper grounding braid
  • 5 ft of 190 mm heat shrink tubing
  • 1 box of heat shrink tubing, assorted sizes from 1.5 mm to 13 mm
  • 2 sets, aviation style 12-pin connectors, male and female, with 5 amp pins and end cap (search eBay: “Aviation plug Disc flange assemblies DF-20 12-Pin XLR Radio 20mm Panel waterproof”)
  • 3 sets, XT60 connectors, male and female
  • 3 sets Deans Ultra Plugs, male and female
  • 4 sets, 6-pin JST-XH connectors, male and female
  • 2 11-pin JST-XH connectors, female with pins
  • 1 sheet of stick-on fish paper. Insulates battery assemblies from each other.
  • 1 sheet of stick-on fish paper discs, 18 mm diam with 8 mm holes. Insulates the positive battery ends.
  • 2 sets of small brushless motor connectors, male and female
  • 1 spool of 60/40 rosin core solder, 1mm diam 63/37 rosin core solder is better, if available.
  • 1 bottle of good quality liquid brush-on flux
  • 1 bottle of black CA glue
  • 1 bottle of CA accelerator
  • 1 two-part Arctic Alumina thermal adhesive
  • 1 13mm roll of Kapton tape
  • 1 roll of 1 inch blue masking tape
  • 2″ x 2″ x 1/8″ birch plywood, aircraft grade
  • Assorted warp-free scrap-wood, 1/8″ to 1/2″ thick (see pictures)

And these tools:

  • 50 Watt soldering iron with a new 5/16″ or 4 mm flat bladed tip. for soldering braids onto cells.
  • 25 Watt soldering iron with small conical tip. for soldering small connectors.
  • Brass-wool soldering iron tip cleaner
  • Good quality hot-melt glue gun with dual temperature glue
  • Electric drill with drill bits 1/16″ to 1/2″ diam
  • DC voltmeter
  • Dremel Moto-tool with drum sander and various plastic cutting tips
  • Dremel Flex Shaft
  • Heat gun or modified hair blower
  • Thin razor saw, 9 mm wide. e.g. 4-in-1 Zona-tool saw set or equivalent
  • Xacto knife set with multiple blades
  • 2 Goot heatsink clamps. for electronics work. very useful!
  • JST-XH crimp tool. useful but not essential. careful soldering works as well.
  • Panavise or equivalent
  • Helping Hand with magnifier
  • Safety goggles
  • Workman’s gloves. dish-washing gloves work well.
  • 1 sheet Scotch-Brite non-metallic pot cleaner
  • Various needle-nose pliers, diagonal cutters, screw, Torx and nut drivers, small files, etc.

Step 2: Battery Dissassembly

As you disassemble your battery you may find another surprise waiting for you: point-to-point wiring. To save space and lower costs BionX apparently chose to forego connectors and solder their packs together using very stiff coarsely stranded wire. Soldering point-to-point by hand with live voltages present, however, can be dangerous, so I installed Deans Ultra Plugs and XT60 connectors to improve safety and make it easier for me to do my own repairs later. I can now pull the battery or electronics board out with just a pull of a few connectors instead of having to cut them out with diagonal cutters. I also found the coarsely stranded power wires difficult to bend in the tight space available to them so I replaced most of them with super-flex wires of the same or heavier gauge to make reassembly easier.

Before cutting the wires be sure to pull the 30 Amp auto-style fuse off the electronics board and take pictures of everything so as to have a record of how it all connects together. I like to make “Pencil CAD” drawings as well as that forces me to trace each wire end-to-end and learn more of the layout. As space is very tight in there you’ll have to be extra careful with the connectors and wire lengths when the time comes to stuff it all back inside.

My pack came with two temperature sensors.- one a thermal switch glued to the top of the pack and the other a Type K thermistor glued to a cell inside the pack. The thermal switch opens during charging when the pack’s temperature goes beyond a certain level and acts as a fail-safe cutoff in case the pack overheats. The thermistor monitors the pack’s temperature during discharge and can signal the microprocessor to reduce power to the motor during, say, a climb up a long hill to prevent damage to the pack. I recommend you retain both these devices and glue them onto your new pack using Arctic Alumina thermal adhesive. You should also reconnect them to the circuitry using suitable connectors rather than splicing them back together. For that I used some old, small brushless motor connectors that I found in my junk box and covered them with heatshrink for protection against shorts.

Step 3: Balance Port

And now we come to the new balance port. This part took a lot of thought but came out very well. What was needed was a small but robust 12-pin connector set that could take 22 gauge wires and frequent insertions. After much searching I found a 20 mm aviation-style 12-pin plug and socket set on eBay. The silver-plated pins of this pair can pass up to 5 amps each and both connectors will just fit in the space opposite the battery’s plunger lock. The wires came from a length of 12-conductor stranded 22 gauge cable I also found on eBay. Each wire has a different color which can help you avoid confusion when wiring up the different cell groups. When soldering the pins, make sure you tin both wire and pin before joining them together, then cover the joint with 1.5 mm heatshrink. Work from the center out, that is, pin 12 on down, as you won’t be able to get to the inner pins if you go from pin 1 up. You don’t need pin 12 but I put a wire on that anyway just in case it was needed later. If you organize the colors to follow the standard resistor color code, i.e., black for ground, brown for cell 1, red for cell 2, etc., you’ll find it easy to put them in the connectors in the right order. Also, stripping off the cable’s outer insulation will make the individual wires easier to work with. When done, you can always twist them back together by chucking them into an electric drill.

The connectors on the end that attaches to the battery had to be smaller but needn’t be so robust so I chose two inexpensive male 6-pin JST-XH connectors, one for ground and cells 1-5, and one for cells 6-10. The pins on these, normally meant for circuit boards, must be soldered to the wires very carefully as they are very thin and can easily melt the plastic. The battery gets the females of those connectors and the different wire colors will tell you which connector goes to which mate. A separate 2 ft. cable is needed for the charger. It will take the female aviation plug on one end and an 11-pin female JST-XH connector on the other, following the same color order.

To install the balance port socket, I built a mount out of a piece of 1/8″ thick birch plywood and used a Dremel drum sander to sand and bevel it to exactly the right shape to fit inside the empty space opposite the plunger lock. If you do the same, mount the socket to the plywood without the rubber gasket that came with it using M2 flat head bolts (with nuts), then use a strong glue, such as black CA, on the beveled edges making as much wood-to-plastic contact as possible. The bond needs to be strong as the 12-pin aviation plug requires some force to pull from its socket. Glue it in at an angle to accommodate the long plug and make sure the socket won’t contact the rack assembly when you slide the battery in place. I had just enough room to fit on the dust cap after trimming away the excess rubber (see pictures). Remember that the cable must also pass through a 1/2″ hole into the battery compartment. To cut the hole I used a 90 deg attachment on my Dremel but the result was less than pretty. A Dremel Flex Shaft might have been a better tool for this but I didn’t have one at the time.

Step 4: Optional Charge Connector

For the charger power inlet, I chose to glue in a female XT60 connector near the plunger lock, mostly because I wanted it protected from the rain and I couldn’t find an XLR connector that fitted the original BionX side connector. Although the XT60 fits in the small space and works well, it did add more wires to the electronics cavity making it that much more crowded. If you can find a male XLR connector to fit your BionX connector then I suggest you go with that, or cut off the one from your old BionX charger and use it to make a new cable for your new charger. This will save you some space in the cavity. If you do use the XT60 connector fit it in very carefully as there is just enough room for it to fit without striking the rear rack as you slide the battery in place.

Step 5: Battery Layout and Preparation

The original battery was assembled in a layered 7-6-7 cell scheme using custom-cut nickel sheets that were CNC spot-welded to overlapping 8-cell clusters. I didn’t have a spot-welder, nor did I feel like building or buying one, so I used 1/4″ pre-tinned grounding braid and solder to build my pack. This worked quite well and was easier to build than soldering nickel sheets, or even strips onto the cells, but one must be very careful to solder the right cells together.

After much thought I decided on a flat, cell-to-cell layout connecting the cells in a single line (see the drawings) rather than modifying the original 8-cell overlapping cluster design for a 10S6P pack. The latter would have required 12 cells overlapping each other and that would have made constructing a neat pack quite difficult. Using braids, which are more flexible than nickel strips, and connecting them cell-to-cell also allowed more precise soldering and the least transfer of heat into the cells. The braids did require a bit of custom shaping of their own but that was easily accomplished by cutting notches and pre-soldering angles into them to accommodate the changes of direction (see Step 7).

At this point it is a good idea to make the sheet insulators out of stick-on fish-paper or other stick-on battery insulator material. Peel off one of the insulators from the old battery and use it as a stencil to make six exact copies. Don’t try to use the old insulators in the new battery as they will likely not stick on well. Also, make or acquire 60 life-saver shaped 18 mm diam fish-paper insulators for the positive end terminals.- you don’t need them for the negative ends. These will help prevent the braid from bridging the short distance between the positive pole and the negative can lip. Mine did not come with the holes so I had to invent an 8 mm hole punch and punch them out by hand.

Also, while they are still loose, rub both ends of every cell in a twisting motion under your thumb with a clean sheet of non-metallic Scotch-Brite (supermarket variety is fine) and blow away any dust that forms. Do not use sandpaper as the grit can lodge under the can’s lip and cause shorts if it is at all conductive.

Step 6: Battery Assembly

I recommend you make full-sized drawings of the battery ends (both ends, all three assemblies) to be able to visualize the battery and braid placements. On a long piece of paper (such as a cut open envelop) again use the old insulator as a stencil and draw six images in two rows of three (see pictures). Use an 18 mm diam washer with a 10 mm hole to draw in the positive and negative poles, then draw in the braids. Double check the drawing at least a dozen times. (seriously!) to be sure you have the batteries oriented properly. You don’t want any designed in shorts, trust me.

Next, build a 130 mm x 66 mm box out of warp-free scrap-wood and extend the base a foot or so in one direction so it can be clamped to your tabletop (see pictures). With your full-sized cell layout drawing in front of you, place strips of Kapton tape on the sides of the cells that will touch each other and put the first layer of seven cells in the box per the drawing. Spread hot-melt glue on the tape in the valleys avoiding the ends and making as small a bead as possible, then invert the cells and glue the other side in like manner. Kapton tape resists temperatures to 500 deg F. and can easily take the heat of the hot-melt glue. If you ever have to disassemble the pack, you can just peel off the tape without ruining the cells’ heatshrink coverings. I didn’t learn this trick until after I’d laid down my first layer of cells but each succeeding layer did get the tape treatment.

The middle layer has six cells and the top layer, like the bottom, has seven. When all three layers are assembled, stack them in the right order and tape them together with Kapton tape. Put a few tacks of glue on the end cells to keep the layers from shifting. Assemble the remaining clusters in the same manner, following your pencil drawing exactly and noting the different cell placements in each.

Step 7: Braid Preparation

Before you start soldering, a word about solder technique: A new 4 mm chisel-point tip in a 50-watt iron, frequently applied flux, and counting to three every time you touch a cell with a hot iron is essential to avoid damaging them with excessive heat. Make it a rule to remove the iron after three seconds regardless of whether you’ve made a good bond or not. You can try again after the cell cools, but avoid doing that more than twice. It takes a bit of practice, but if your surfaces are clean, your iron is clean, you’ve applied liquid flux to every surface top and bottom and pre-tinned each surface then you should have little trouble soldering the cells together.

Next, stand an assembled cell cluster inside your box to hold it in place and put the life-saver shaped insulators on each positive end, then brush on some liquid flux on all ends, positive and negative. With a new 4-mm chisel-point tip in a 50-watt soldering iron, put a blob of solder in the center of each end taking care to not touch the cell with the iron for more than three seconds. Good quality 60/40 or 63/37 lead solder should flow on quickly and almost cover the positive electrode and about 1/4″ of the center of the negative one. Do not use lead-free solder as it requires too much heat.

Prepare the braids according to your drawing. Make the shorter ones first and save the longer ones that connect the clusters together for later. Always make the braids in one piece to avoid soldering them on top of one another which will require too much heat and make the cells too long to fit the enclosure. Cut notches 3/4 the way through at the turns with sharp diagonal cutters, form the bend, and solder the bend together using as little solder as possible (the braid will need to absorb more solder later to bond with the cell ends). Tap the soldered bends with a small hammer to flatten them to the same thickness as the rest of the braid. Each braid should exactly fit its corresponding cell tops with no off-center bends and no excess length. The two exceptions are the 6-cell positive and negative end braids which will get one inch or so of extra length to allow you to solder on the red and black power wires. Brush flux on the entire solder side of the braid and mark it with a Sharpie pen at the central contact points for each cell. Finally, put a small blob of solder on all the marked spots, again following the three second rule to avoid flowing on too much solder. Just a small blob to match the cells is all you need.

Before test fitting the braids, be sure to put lots of blue masking tape on the cell ends that you are not connecting together and only leave exposed those that you are. This will help minimize accidental shorts. Just to be safe, I also tested every exposed cell against its neighbor with a voltmeter before laying down the braid to be certain there was 0 volts between them. If you ever find you’re about to solder two adjacent cells that show a voltage between them, you WILL get sparks when you lay down the braid! You should get something between 0 and maybe 20 millivolts depending on how well equalized the cells’ charge states were before you began your construction. My cells were new and even though I delayed construction for 3 months, they still showed less than 10 mv between them when I finally built my pack.

Step 8: Soldering the Cells Together

When you’re ready to solder the cells together, reapply flux to the cell tops and the bottom of the braid at the places you tinned, position the braid in place and choose an end cell for the first joint. Since they’re pre-soldered you do not need to apply more solder. With one hand apply the iron to the braid as flatly as possible to transfer heat as quickly as possible, count to three, then remove the iron and, in one smooth motion with your other hand, quickly press a small screwdriver onto the joint to hold it in place while the solder hardens. Again, this whole process should not take more than three seconds. The cell should be cool to the touch a few seconds later. If it takes longer than three seconds to make a bond then your iron is likely less than 50 watts and not up to the task. Smaller irons force you to contact the braids for longer periods actually transferring too much heat into the cells, larger irons are clumsy and just as apt to transfer too much heat, so I don’t recommend them either. Mine is a Hakko Presto 980 dual power iron that goes from 20 watts to 50 watts nearly instantly at the press of a button. Finish the line of cells from one end to the other, then remove any escaped solder balls with needle-nose pliers to prevent them from causing trouble later. Cover this line of cells with fresh masking tape and uncover the line you wish to solder next.

The four braids that connect the clusters together will be longer and need some extra care in their construction. All four will fold 180 degrees and require some good quality heatshrink to keep them from shorting against each other or the sides of the cans. The short-spanned ones will need no more than 3/16″ to go between the clusters.- any longer and the folded braid won’t fit inside the enclosure. Also, too much solder in these spans will cause them to not bend easily. Placing a Goot heatsink clamp in the middle of the spans while soldering them in place might help you avoid that problem, but insulate the clamp’s jaws with masking tape or glued on bits of cardboard so they don’t short against the cans. Don’t tape over the jaws’ teeth as you need metal to metal contact for good heat flow. These spans will have to be insulated with black tape as you can’t get heatshrink tubing on them once they are soldered in place. The long-spanned braids must traverse the length of two cells end-to-end so will need 5 3/8″ inches between clusters to cover the distance after they’re folded. Put two heatshrink tubes on before you form the braid so you can move them around as you make your bends. Two 3″ pieces, slightly overlapping in the middle, will give you some length adjustment later without having to cut them.

Step 9: Balance Wires; Thermistor

Next come the balance wires. Cut 2 ft. lengths of all 12 colors and solder them onto the braids following your drawing and the resistor color code. I put their most convenient braid locations on my drawing and numbered the spots 1 to 10 to match the series cell groups. The black power cable braid also gets a wire for the balance ground reference. When the pack is folded, the wires for ground and cells 1-5 should run along one side of the pack and the wires for cells 6-10 should run along the other side. Test them afterwards with your voltmeter to be sure each colored wire goes to the correct series cell group.

For the thermistor, carefully trim off most of the old glue and re-glue it to one of the middle layer cells in the black power cable side recess using Arctic Alumina thermal epoxy. Solder one thermistor wire to the black power cable braid and use the 12th wire (pink) to extend the other to the electronics board area. I added a small brushless motor connector here to allow for an easy disconnect later.

Step 10: Folding the Cell Clusters Together

It takes a bit of finesse to fold the three clusters together. You don’t want the braids to touch each other, even briefly, during this process so tape some temporary cardboard insulators on the ends to prevent shorts. You also don’t want the braids to twist so be very careful when flipping the clusters around while you tape up the balance wires in the side recesses. The wires must not add any width or length to the pack.

With all wires loosely in place and the pack still in a Z- shape remove the cardboard and stick on the fish-paper sheet insulators you made earlier. Fold the pack into its final shape making sure that the clusters fold evenly and tightly together, then pull and tape the balance wires into their final position. A slight variation in the width of the pack of even 1/16″, such as a slight skew or a balance wire resting on the outer edge of a cell, could keep the enclosure halves from closing properly.

The power cables will also take some careful attention. Cut 11″ lengths of black and red 12 gauge super-flex wires and solder them to a female XT60 connector. I again used a heatsink clamp here to keep the solder from wicking up the cable and stiffening the wire. Don’t forget to put on heatshrink tubing for both the connector pins and the braid ends, then solder them to their respective braids. The black negative cable will run along a side recess next to the middle layer of cells. The red positive cable just has to exit the front of the battery, but you will likely have to loop it around 180 deg in its recess to avoid damaging the braid to which it is attached. Loop and tape any excess 22 ga.wire in the side recesses to keep the lengths as short as possible as there is very little space in the front cavity for excess wiring.

The last of the battery wiring is to put the two 6-pin female JST-XH connectors on the balance wires. As with the aviation connector cable, the wires for ground and cells 1-5 go in one JST-XH connector and the wires for cells 6-10 go in the other. I soldered the female pins onto the wires using a “helping hand” but if you have a crimper then by all means use that. Be sure to avoid “insulation creep” at the connector pins and be careful inserting the pins into the connector bodies as you don’t want them to touch each other. You should really put them in the connectors first, then solder the wires onto the battery, but measuring the wire lengths exactly while the pack is still open can be tricky. Another option is to pre-wire your connectors and solder the battery points with separate lengths of wire, then splice and heatshrink them together somewhere in the side recesses after the pack is fully folded. Commercially made pre-wired connectors will also work but they use thinner wires than my 22 gauge wires and don’t follow my color scheme so I chose not to use them.

Step 11: Final Pack Assembly

Once the pack is folded and the wires tidied up you can tape the three cell clusters together using Kapton tape. The pack should then hold its shape well enough to be handled. Check that the clusters are not askew with each other and that the interconnecting braids protrude as little as possible from the sides. Now you can cut a piece of the large 190 mm shrink wrap to fit the battery with four inches of overhang on each end, slip in the battery and shrink it down. Flatten the end flaps with gloved fingers. Do not use foam padding as there is no room for it.

The final step is to glue the old thermal switch back in its rightful place on top of the pack. Cut it off the old shrink wrap (don’t try to peel it completely off as you might damage the switch) and glue it on the new shrink wrap directly over a cell using Arctic Alumina thermal glue. I also replaced its wires with more flexible ones and added a Deans Ultra Connector to allow easy removal later. One switch wire goes to the XLR charge connector and one goes to the electronics board, it makes no difference which. After a final check with your voltmeter to be sure that all is well with the pack and balance wires, it’s time to sit back, have a drink and admire your handiwork!

Step 12: Fitting the Battery in Its Enclosure

It’s a good idea to at this time replace some of the really stiff BionX power wires with more flexible ones to make the final assembly easier, but only do that if you’re skilled at it. The board is conformal coated for moisture protection and durability and that can make pulling wires off it without damaging the board or components difficult. Use of a desoldering station, if you have one, or at least a good solder-sucker and various pliers and hold-down tools is mandatory.

You can now test fit the finished battery in its case. If you used braids you’ll probably find that the battery is too long to fit within the enclosure’s molded-in stops, which were designed for spot-welded batteries. However, I was able to make my battery fit by cutting away the stops in the rear only, including two that were just straight bars of plastic about an 1/8″ wide and an inch or so long running parallel to and near the rear screw channel (see pictures). The screw channel, only a 1/4″ away, will serve nicely as your new stop. Choosing the right tools to cut the excess plastic out, though, is important. For me, the best tool was a 9 mm wide backless razor saw from a Zona-tool 4-in-1 saw set. It cut the thin bars out nice and flush with the sides. The Z-shaped stops were dealt with using a combination of Xacto knife blades and Dremel plastic cutting bits.

If you find your enclosure halves don’t quite close all the way, it may be because something on your battery is protruding too much. I found that one of the short folded braids protruded just a 1/6″ at the fold point contacting the side wall of the enclosure. Fortunately, at that location there is another bar of plastic about 1/2″ wide by 1/16″ deep running the full length of the enclosure’s side. Some careful work with a Dremel cut out a nice divot in that bar and that gave me just enough room for the folded braid to fit.

With the battery and case successfully test fitted you can now install the electronics board in its cavity. As I had guessed at the lengths, I found my power and braid cables too long so had to shorten them. With live voltages present, though, that was is a bit dicey to say the least! I carefully rebuilt my connectors, but in retrospect I suggest you splice your wires somewhere mid-way in their lengths and cover them with heatshrink to avoid the possibility of creating shorts.

Step 13: First Charge and Test Results

I chose 10 amps for my first charge, which I calculated to be slightly less than 0.5 C, but the thermal switch opened about 30 minutes into the charge. I then lowered the charge rate to 8.2 amps, which is about 0.4 C and it worked fine for several more charges with no aborts. That is, until I decided to do a complete cycle test to determine the pack’s full capacity. The discharge at 2.0 amps went uneventfully but the following charge, done at 8.2 amps, caused the thermal switch to open again about 3/4 the way through when the pack overheated. Seems the longer charge time from a fully discharged state (3.0 V/cell) didn’t take well with my fancy-dancy hoverboard fire protector bag which probably acted like an efficient thermal blanket and didn’t allow any ventilation to dissipate the heat. I’m therefore very glad I had reinstalled the switch because it protected my new battery from damage. Lesson thus learned, I now charge the pack at 6.0 amps while leaving the bag’s top flap open and have had no heat buildups nor aborts since.

It takes a bit more than two hours at 6.0 amps to charge the pack from the nominal 3.7 volts/cell and maybe five hours from a fully depleted 3.0 volts/cell. However, I don’t let the pack get down that low and don’t plan to do cycle tests more often than once a year. I also don’t charge it beyond 4.1 volts/cell even though the new cells are rated at 4.2 volts, which gives me about 98% capacity. My internet sources tell me that the battery will last through twice as many charge cycles and that the few sacrificed minutes that 0.1 volt represents are well worth it!

BTW, if you leave your pack in storage for long periods it is advisable to lower the charge rate to 2.0 amps and charge the pack every six months or whenever the pack “chirps”. At that point the cells are approaching 3.7 volts/cell which is the point when the control board recommends you head home and recharge the pack. The idea is to give you some reserve but avoid as much as possible over discharging the pack on the way home. The same monitoring occurs in storage but the lower charge rate will help equalize the cells without shocking them.

So how well does the new pack perform? The bike easily goes 20 miles now on a single charge up and down the hills of my city which are often quite steep, all the while staying above 36 Volts, and I’m sure I can get it to go 30 miles if I let the voltage go lower and I do more of the pedaling. If I lived in a flat city and only used the BionX torque-assist mode I could probably stretch it to 40 miles. A single charge lasts me at least a week now, including daily commutes to and from work and various shopping trips, whereas before I averaged only one or two days. This is easily three times the old battery’s capacity on its best day, and the power is strong with no sags or heat buildup no matter how hard I ride the bike. As I seldom let the charge get lower than 36 volts, I can pretty much avoid the chirps coming from the pack telling me its time to go home and put away my toys.

The cycle test indicated a full 18.4 Ah (680.8 Wh) of capacity and would probably have reached 19.0 Ah (703 Wh) if I had let the charge go to a full 42 volts. That compares with my old battery’s 6.4 Ah (236.8 Wh) rating, and I don’t think it was ever that good even when new. As for weight, the pack is now an even 9.0 lbs, up from 6.5 lbs for a 2.5 lb gain.- not a bad weight penalty for tripling the range of the old pack! I am quite pleased with this performance!

Step 14: Bonus! How to Wire a 7 Cell Battery Capacity Checker for 10 Cells

So now you have a new 10S6P battery pack and you’re zipping along on your e-bike enjoying the fresh air, but from time to time you’d like to see how well the ten cell groups are holding up. You notice that the battery indicator in your BionX control panel shows “empty” at around 10 miles even though you know you’re still above 38 volts at that range.- plenty of charge left for another 10 miles at least, maybe 20 if you go easy on the throttle.

To read how much tank you really have left you could use a digital Battery Capacity Checker like those available on eBay and Amazon. They’re inexpensive and work surprisingly well, but are built for a maximum of only 7 cells. To make one work on 10 cells you need an adapter cord that connects to your battery’s balance port on one end and splits into two 6-pin JST-XH connectors on the other end. You then wire the connectors for two separate cell groups; one for ground and cells 1 to 5, and one for cells 5 to 10. That’s not a misprint. The important point to remember is that the positive wire for cell 5, on connector #1, must split and serve the additional function as the ground wire for cell 6 on connector #2. The battery checker doesn’t care where the ground is as long as there is one and that the cell voltages go up from there and in the proper order. As both connectors are not connected simultaneously there’s no risk of shorts between them. Just remember to always plug your connectors into the checker pins to the right of those marked “6” and “7” (you could also use 8-pin connectors and simply not wire up pins 6 and 7). Though the battery must be removed from its rack every time you check it, the checker’s low cost, light weight, and easily read display make up for it.

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Good luck, drive safe, and happy trails!

Re-cells the e-bike battery

Adjusting the battery of the electric bike, i.e. replacing the battery cells! Making cells is clearly cheaper than a new battery. By repairing the old you will also save the environment.

We make cell cells for electric wheels, contact us and find out how your old battery can be saved!

Contact us by email info @

When sending the battery, be sure to bring the charger! Why? Here are three reasons:

We check the performance of your charger – sometimes the battery malfunctions are caused by the charger used and does not fully charge the battery, for example.

After work, we will make sure that the battery is charged correctly and fully charged with your charger. After that, we can see the outcome of the work, i.e. what the power of the sensor was your aability to do.

This is all included in the job price!

Not in stock, only as backorder

Tuotetunnus (SKU): sahkopyora-akun-kennotus Osasto: Akkujen kennottaminen Avainsanat tuotteelle kennottaminen, kennotus, sähköpyörän akku


The re-celling of a battery of the electric bike saves money and nature! Replacing the new battery cells is a cheaper way to get the wheels rolling again. The battery usually dies in winter because its voltage drops too low (less than 2.5V in the battery).

Batteries for use in electric wheels

In Finland, almost all e-bike batteries use li-ion or li-po battery cells. The advantage of lithium batteries is light weight and high capacity and power supply in relation to the size of the battery. The weakness of lithium batteries is sensitivity to overcharging or undercharging. For example, the battery cell 18650 li-ion, which is the most used battery cell for electric bikes, requires a charge of 2.5V to 4.2V. Therefore, aBMS (Battery Management System) (Battery Management System) has been added to the battery packs.

The function of the BMS is to monitor the cells in the battery pack and to interrupt the discharge or charge when the battery reaches the programmed voltage level. Due to bms, lithium batteries are quite simple because the cyclist does not have to measure the battery charge, but the BMS stops the power supply. Thus, the battery runs out before it reaches dangerously low voltage. So it’s the same as on the phone. The phone reports a battery charge of 0%, but in reality the battery still has power to prevent deep discharge from damaging it.

Probattery tips for maintaining the battery of an electric bike:

  • Do not disassemble the battery too empty! If possible, do not disassemble the battery in less than 20% of the charge. The lithium battery starts to oxidize in too low a charge. Keep the battery in a 60-80% charge, especially when storing. In winter, it is a good idea to charge the battery every three months.
  • If the battery is hot, allow it to cool down before charging. The battery may warm up when discharged with high current. Heat is especially the enemy of the li-po battery. Battery chemistry stays smoother and in good condition for longer if you do not charge the battery when it is hot.
  • Keep the battery close to room temperature. The frosty winter in Finland absorbs the juices from the batteries if the battery is left cold. Similarly, temperatures above 40ºC over time interfere with chemical reactions in the battery. Take the battery in for the winter and in the summer store in the shade.

How long does the e-bike battery last?

The cyclist’s driving style affects the life of the battery. Hard accelerations require more power from the battery. The lithium battery can withstand about 500 recharges. This can be greatly reduced if the battery is constantly discharged with high currents. Some wheels prioritize the range and battery age by limiting the battery output.

Lithium battery performance is always a compromise between capacity and power supply. The maximum capacity of the 18650 battery is practically 3500mAh or 3.5Ah. The maximum power is approximately 35 amps from a battery cell of that size. However, these features can never be obtained in the same battery cell.

A high range is obtained by selecting a high-capacity battery sensor, such as Samsung 35E or LG MJ1. These 18650 batteries offer 3.5 Ah capacity, but the maximum discharge current is only 10 amps. If you want more power off your bike, you can choose between high discharge battery cells such as the Sony VTC5A or Molicell P26. These batteries have only 2.6Ah capacity, but a wild 35A power supply.

Of course, by connecting the batteries in the chest and series, you can get more familiar readings, such as 36V and 418Wh. Well, what do we just talk about amps and now all of a sudden watt lessons?

The Shimano BT-E6000 e-bike battery is powered by 18650 li-ion cells with a rated voltage of 3.6V. It can therefore be calculated that the battery is connected in a series of 10 batteries. 36V / 3,6V = 10.

The amps are obtained by dividing the wattage hours by voltage, i.e. volts. 418Wh / 36V = 11,61 Ah. Then, when it is known that shimano’s battery has 40 cells, 11.61Ah can be divided by four. Four because we already know that there are 10 batteries in a row, so in parallel 10 sticks there are four.

11,61Ah / 4 parallel connections = 2,9 Ah. So we know that the battery uses 40 pcs of 18650 batteries with a capacity of 2900mAh.

This is a good idea to know if you’re wondering which battery cells you’d use to update your e-bike battery.

What should I take into account in the battery of an electric bike?

The e-bike battery package can be built according to the user’s needs using high-capacity cells or high discharge cells. The most common need is to maximize travel, meaning we usually put LG MJ1 18650 cellsto provide 3.5Ah capacity per sensor. Another excellent, slightly cooler option is the Panasonic-Sanyo NCR18650GA 18650 battery cell,3.5Ah capacity and 10A discharge.

The lithium battery possible bms is also the hardest element in the battery. The BMS charge control circuits from the manufacturer have pre-programmed in-control. It involves not only monitoring battery performance, but also discussion sup with the bike management system. For example, the battery tells information about its charge to the bike’s driving computer, which requires much more complex programming. Of course, e-bike manufacturers do not sell separately BMS circuits, but directly from new batteries.

BMS is the biggest challenge for the do-it-yourself construction. The battery pack may keep the battery dead if it has been empty for a long time. Even if the cells are loaded separately back into a good reserve, the programming of BMS cannot usually be changed at home. In this case, you will need to buy a new battery or put in a generic bulkkiBMS that monitors the battery cells, but does not know how to do anything else. Then the electric bike can run on an old battery, but it no longer knows the same tricks as the original.

Do-it-yourself e-bike battery

Only BMS status is an obstacle to those who are handy with their hands. If the BMS is very awake in the battery, but the battery cells are tired, the cells can be replaced.

Here’s a good example for english speakers in the video:

The video makes 13S2P, or 13 cells in series, 2 parallel battery packs. It uses Samsung INR18650-25R 18650 battery cellsthat provide 20A continuous discharge current and 2.5Ah capacity. The parallel connection of two cell lines means 5Ah capacity and 40A discharge current in the battery pack. 13 cells in a stick, i.e. when connected in series, make the battery pack 13x 3.6V = 46 V.

What does it take to get a battery?

When building the battery pack, the battery cells must be as close as possible to each other. In the worst case, if the battery has a high voltage difference, you can build a battery that has not worked.

Connecting the batteries into a battery pack is done by spot welding. Spot welding is practically the only working way, as knocking heats the battery too much and at worst spoils the entire cell.

Spot welding supplies electrical current to the welding site, which provides the heat required by the weld. The result is a very neat welding result and the battery cell remains intact.

For more information on how to design and build your battery, see Visit at least check out the images.

Custom-made e-bike battery

If your battery is running out of time, you can also send it to us. We’re analyzing the potential for that condition and re-encapitsion. After the measurements, we agreed with the customer which direction to go with the project. We can order any battery cell from the battery pack, including the new 20700 and 21700 battery cells.

The cost of work consists of battery cells and work done. Depending on the complexity of the battery, the work can cost 150-200 euros. As a result, we’ll send back a battery that probably has better features than original ones. (No need to use the most cheap cells, so you can maximize, for example, the capacity of the battery size within the limits allowed.)

The cells of the e-bike batteries depend a lot on the battery structure and desired features, so please contact us by email info @

At least the battery model and preferably a picture of the battery should be attached to the message. Let’s build the batteries that are right for you!

You can send the battery to:

  • Jesi Verkkokaupat Oy
  • Pääskynlento 13 B 43
  • 20610 Turku, Finland
  • 045 263 8565
  • Don’t forget to bring the charger!

The truth: How far can an electric bicycle really go on a single charge?

One of the biggest benefits of electric bicycles is that they can help riders go farther with the same amount of leg power. But with manufacturers citing wildly different range ratings for seemingly similar e-bikes, how can you know what an e-bike’s true range is?

It’s actually easier than you’d think. And after spending more than a decade working in the electric bicycle industry, I’ve gotten decently good at it, if I may say so myself. Here are my tips to get a true, honest range rating out of an e-bike.

What are the factors in e-bike range?

First things first: One of the reasons e-bike range ratings seem to be all over the place is because they can be affected by a number of factors.

Everything from speed to rider weight to terrain style to wind conditions and even tire choice can impact an e-bike’s effective range on a single charge.

The second major factor is the presence (or absence) of a hand throttle. Most European riders won’t have to consider this since e-bike throttles aren’t common in EU countries. But for Americans and riders in other countries that allow hand throttles in addition to pedal assist, a hand throttle can be a quick way to drain battery and reduce range.

A throttle might be convenient, but it will drain battery quicker than pedal assist

How to estimate e-bike range

To determine an e-bike’s approximate range, you first need to start with the battery capacity. It is usually measured in Watt hours (Wh). Sometimes you’ll see a battery rated in volts and amp hours, such as an e-bike with a 48V 10Ah battery. To convert to Wh, simply multiply the volts by the amp hours. A 48V and 10Ah battery is therefore a 480 Wh battery.

Next, you can calculate effective range by simply dividing the watt hour capacity of the battery by an average efficiency number in Wh/Mi (or Wh/km if you prefer kilometers).

This is the slightly fuzzy part of the math, since efficiency numbers will vary based on the factors listed at the start of this article. But speaking generally, I find that most 500-750W throttle e-bikes ridden at an average speed of 20 mph (32 km/h) on only slightly hilly terrain get me around 25 Wh/Mi (or 15.6 Wh/km). Thus an e-bike of this style with a 480Wh battery would provide me with around 19 miles of range (480 Wh ÷ 25 Wh/Mi = 19.2 miles).

Pedal assist will always be more efficient. I find that most pedal assist e-bikes ridden around 15 to 18 mph in medium levels of pedal assist will get me around 15 Wh/Mi (or 9.4 Wh/km). Thus the same 480Wh battery on a pedal assist e-bike will provide me around 32 miles of range (480 Wh ÷ 15 Wh/Mi = 32 miles).

You can use the same math for various sizes of batteries to calculate an estimated range under real world conditions. However, you might want to make adjustments to the numbers to better fit your needs, as I explain next.

You can adjust these numbers to fit your specific scenario

For reference, I weigh around 155 lb (70 kg). If you’re a bigger guy, you might want to use a figure closer to 30 Wh/Mi on throttle bikes, for example. Or if you’re a little slip of a thing, you might get closer to 20 Wh/Mi. My wife always gets better range than I do, and the fact that she weighs 45 lb (20 kg) less than me is a big part of it. weight means the bike has to use more energy, especially on acceleration and hill climbing.

You can also edit these numbers based on terrain. I usually ride in only slightly hilly terrain. If you’re riding around on a pancake, you can use slightly better efficiency numbers. If you’re climbing bigger hills, you’ll want to use slightly worse efficiency numbers.

But for starters, 25 Wh/Mi on throttle e-bikes and 15 Wh/Mi on pedal assist e-bikes is a good place to begin for a reasonable range estimate.

What if I’m a really strong pedaler?

I’ve got you strong pedalers covered, too!

I usually ride around with a mid-level pedal assist mode selected, which is why I get around 15 Wh/Mi on most pedal assist e-bikes. That’s a solid figure for me when I’m commuting or running errands. At those times, I’m certainly using my legs to add assistance, but I’m not going nuts with the fitness.

However, when I really want to get some exercise, I stick to pedal assist Level 1 and the efficiency can often skyrocket. I recently documented a 29 mile (47 km) e-bike ride I performed where I used only 90Wh of energy by remaining in Level 1 pedal assist as much as I could. That worked out to a crazy 3.1Wh/Mi!

I was pretty much dead after that ride, so I wouldn’t recommend riding at that level every day unless you’re a very fit cyclist (I’m not), but it was a great experiment to see what can happen when you push yourself and your bike to the limit.

What about extreme range ratings on e-bikes? Are those true?

We can use these equations to test out some examples of ultra high-range e-bikes to see if the manufacturers are being realistic.

The Specialized Turbo Vado SL e-bike was recently released and came with an 80-mile range rating from its 320Wh internal battery or 120 miles with an extra 160Wh booster battery.

At my normal efficiency of 15 Wh/Mi with medium pedal assist, that bike would likely take me around 21 miles with its built-in battery or 32 miles with its booster battery. Realistically though, the narrower tires, lower weight and higher efficiency of that bike will likely result in a bit better range than that, as I’ll be riding more efficiently than I do on most of my cheaper pedal-assist e-bikes.

But if I drop it into the lowest pedal-assist mode and get closer to my 3.1 Wh/Mi efficiency when I’m really pedaling hard on that bike, that would equate to a range of just over 100 miles on the internal battery!

Obviously that’s on a sweat-soaked multi-hour fitness ride, but you get the point. By adding more of your own pedal power and using lower pedal-assist modes, the range of an e-bike can be drastically increased, which is where manufacturers often get these lofty range figures.

Ultimately, most people aren’t going to ever hit efficiencies below 5 Wh/Mi, unless they are really pushing it hard and getting a serious workout. For daily riding, 25 Wh/Mi on throttle-only riding and 15 Wh/Mi on modest pedal assist riding are both good figures for real world range estimates.

Have you done your own range testing? I’d love to hear about your experiences — let me know in the Комментарии и мнения владельцев section below!

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