Cordless drill ebike. Prepare your parallel groups for welding

How to Build an Inexpensive Electric Bicycle

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An electric bike is a lot easier to build than you might think! All you need is a bike in good working order, a conversion kit, and a battery. Using a conversion kit makes the process super simple and fast. And if you shop online to find the best deal on the kit and repurpose a bike you already own, this can be an inexpensive project.


  • Choose a bike with wheels that are 26, 20, or 16 as these are the most common off-the-shelf wheel sizes. The smaller the wheels are usually found on folding bikes and will accelerate more quickly, be bumpier, and be less efficient at cruising speed.
  • Mountain bikes are most commonly converted to electric bikes, though you could use a different type as long as it has a strong frame and standard bottom bracket. Don’t use a bike with a carbon fiber frame or forks, as these aren’t strong enough to support the extra weight or handle the extra torque. [2] X Research source
  • Wider handlebars are best as they give you plenty of room for all your accessories and lights.
  • Front disc brakes will make it easier for you to stop on steep hills.
  • Ensure the kit comes with a wheel that is the same size as the existing wheels on your bike! It’s much easier to replace the front wheel than the back, due to the position of the gears, so opt for a kit in which the hub motor is on the front wheel.
  • In most cases, the battery doesn’t come with the conversion kit. For ease of installation, though, it’s best to purchase the battery and the conversion kit from the same manufacturer.
  • The capacity of the battery defines how long it’ll last. If you’ll be taking short trips, a 10Ah will suit you well, while a 20Ah battery will provide you with extra capacity for slightly longer journeys. [5] X Research source

Wheel Replacement

  • To remove the front wheel, turn the bike over so it’s sitting on the seat and handlebars, then flip the quick-release lever over to the “open” position. Then, simply lift the front wheel off of the bike. [7] X Research source
  • To remove the back wheel, crouch behind the bike. Hold the frame with your non-dominant hand and use your dominant hand to pull the derailer backward. Then lift the bike frame up and off of the rear wheel with your non-dominant hand and unhook the chain with your dominant hand. [8] X Research source

Transfer the tire and inner tube from the old wheel to the new wheel. Let the air out of the old tire and use a tire lever to separate the tire from the wheel. Pull off both the tire and the inner tube. Reverse the process to install the tire and inner tube on the wheel that came with the conversion kit. [9] X Research source

  • Adjust the brakes as needed, either by aligning the calipers (for mechanical brakes) or pumping the brake lever (for hydraulic brakes).

Final Installations

  • If you have any other accessories, attach them as well. Secure the speed sensor to the back wheel and connect any displays and gauges to the handlebars with the included hardware. [12] X Research source

Connect the battery to the speed controller and the throttle. Follow the instructions included with the kit to connect each part. Typically, you’ll only need to plug the connector on the speed controller into the connector on the battery, then repeat the process for the throttle. Be sure not to touch the battery wires together, as this could create a dangerous spark! [13] X Research source

  • Alternatively, you could place the battery in a box or basket on the front or back of the bike, particularly if it is too large to fit well on the frame (such as if it’s more than 60 volts).

Secure any loose cables. Use zip-ties to attach any loose parts to the frame. Keep safety in mind as you don’t want any cables to get caught while you’re riding. [15] X Research source

Ride your electric bike. That’s it! You can now cruise around on your e-bike. Just press down gently on the throttle when you’re ready to ride. Go for a test drive in a less populated area so you can get used to it before you take it out on the road.

Charge the bike when necessary. The e-bike battery comes with a charger, making the process super simple. Follow the instructions for connecting the battery to the charger and plug it into a compatible outlet whenever you need to. [16] X Research source

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Use Your Cordless Power Tool Batteries To Power Your Ebike : What Could Possibly Go Wrong?

This article has been a long time coming, but first a little history. My wife and I have 2 houses, hers is 1.2 miles from the road up a 900 ft hill and has an off-grid solar system. She is also Chemically Sensitive so we don’t really have anything that runs with gasoline except our cars. Even the generator that we use in the dead of winter is converted for use with propane so we don’t have to deal with the hassle of gasoline. The lawn has a mind of its own (it’s not really a lawn, more like 600 acres of goldenrod) and we decided for our wedding reception we wanted to actually have a lawn for our guests. On her own volition without consulting the battery expert she went out and bought a 40v Electric cordless lawnmower (it was probably only 36v and they were just liars). 40v on a lawnmower was a joke your boss tells you that isn’t really that funny but you still have to laugh, so after a few attempts to knock down the overgrown weeds we just took it back. The next purchase was a much more expensive 500 EGO 56v cordless lawnmower which turned out to be all kinds of awesome. We quickly fell in love.

The mower was powerful enough to knock down most everything (including 3ft high goldenrod) and for the most part, the design was very solid. The 4Ah battery pack ran for about 30 minutes of hardcore mowing, but it also recharged in about 20 minutes and worked very well with our PV system as long as it was pretty sunny. This article is not a review for an overpriced cordless lawnmower that you will never buy. Instead, this article talks about a very Smart way to buy good lithium batteries with a built-in BMS and a decent warranty from your local hardware store, and then mount and use them on your high-power ebikes. Fasten your seatbelts because it’s going to be a hell of a ride.

A 4Ah Ego battery runs about 199 at any Home Depot store, Its a better deal if you buy it as a Chainsaw or Lawn Mower package.

I recently destroyed 800 worth of 6v Lead Acid Golf Cart Batteries from my wife’s solar system my setting them to equalize for 2 hours right before we left for 3 days to hike in the Catskills with visiting in-laws from Denmark. When we returned to the house it was full of smoke and the battery box was over 200 degrees and there was battery acid everywhere and the batteries were squealing and bubbling like crazy. So I donned an old Spinach container as a face shield and threw on some chemical gloves and carefully disconnected the batteries and carried them outside while trying not to get battery acid all over me. I did what any loving, supportive partner would do and agreed to pay for half of the replacement cost of the new cells (which will be closer to 1500) then I secretly sneaked away with her 500 lawn mower battery and went to my house for the weekend to extensively test them with my ebike.

Moral of the story : Don’t marry me if you want your batteries to live a long full life.

You can a fast charger (left) or slow charger (right) and 56v batteries in a variety of different sizes\weights and power capacities (2.0, 2.5, 4.0 ,5.0 7.0 Ah).

When is 56 volts not 56 volts? When it’s 52 volts

Another marketing misnomer is calling these packs 56v packs when really the rest of the battery industry would call them 50v, 51v or 52v packs, which is closer to the nominal rating of these cells. They are referring to peak volts fresh off the charger which is a hair over 57v, so you probably couldn’t actually sue them, but it sure is confusing. In any case, almost all the companies that make power tools are advertising their 14S packs as 56v so there you go. If you don’t like it then you should write a letter to some politician somewhere that they will almost certainly ignore (it’s their job to ignore you).

The battery and slow charger together are pretty heavy. The quick charger is even heavier (4lbs 4oz but not shown).

There were two ways I tested this battery, one with a modified charger (which was heavy) then I took the charger apart and just used the connector piece. I bought a used slow charger for 20 on eBay shipped. I think there are a bunch of them out there that were floor demos or something because the seller I bought from had 10 of them. I took the charger apart using a security keyed Torx (the ones with the dimples on them). Then I cut the leads to the positive and negative and soldered some wire and some Anderson 45 Amp Powerpole connectors to them. I covered the junctions with heat shrink tubing then carved out a tiny notch on the case. I wrapped the two wires with duct tape, put a small zip tie on there as tight as I could then tucked the zip tie inside the case to work as a kind of strain relief so the cable would not get ripped out.

cordless, ebike, your, parallel, welding

I bought one after getting the intro email. A lot of DIY builds don’t have an obvious place to put a battery, especially a large one. I’ve been using HK Lipos in a handlebar bag, small and light, on a step through. I’d be happy to retire those packs, but the Lipos have worked. These packs would also help to lower the entry point for new builders. The Smart Pie is a nice motor for around 300. Something like the SP and one of these packs plus a used bike? You would own a swell motor and a good battery. Like Like

Another great article, Karl! A few years ago, the only way to get high-amp cells was to gut cordless tools, so I did some reading on them. My first ebike was a DIY friction drive using RC model components, so they operate well on lower voltages. Oddly, the 28V packs used higher-amp cells compared to the 36V cordless tools. If I had begun making and selling friction drives to college students, I was going to use Milwaukee brand 28V battery packs, so I wouldn’t have 18-year olds burning down their fraternity dorms with LiPo. If I was designing a power-board today, I’d use those 28V packs and pneumatic tires… Like Liked by 1 person

Thanks Obi-Wan. Yeah nothing beats those 20R 25R’s for high output, cost and safety. The market drives the industry, the ebike stuff is just fringe and sometimes it feels like we’re all just along for the ride. Like Like

I’ve had an EGO for a couple of years and have wondered about using the battery as a range extender. I have a Catrike based velomobile with a 2000W MAC and a KW-hr of LiFePO4. I think my two bricks weigh ~20 lbs. I could toss my EGO battery in the saddle bags and extend the range 40%. Like Like

You guys are barking up the wrong tree, use 36v 4.4a hoverboard batteries, less than 50 bucks off ebay. Like Liked by 1 person

You are a braver man than I am Dan. Those cheap Lipos are notorious for spontaneously combusting. Like Like

Funny how we don’t really have what we want/need but always seeking what we can use and improvise. My 2 stroke 30yo lawnmower I had since a kid with barely any maintenance was getting to recon time. Wife always wanted to mow lawn and kid across the road was doing their lawn with electric like a cordless vacuum. I saw the 52-56V EGO used on a cruiser ebike (fugly, bulky with charge cradle used as the on-bike dock), we only had 4Ah packs available, so got that and the blower with 2Ah pack, with ebike use in back of mind. Really nice user friendly quality as you’ve shown in this blog. Too bulky for too low 4Ah capacity for ebike I thought, but the 7.5Ah sounds good, and the shared use mower/blower/ebike is the kind of quality battery sharing to help justify long term care and use. In the interim for suitable range the 16Ah 6S HK LiPo in a 12S pair fit in a lunchbox that fits in frame bag for similar size to the Ego 4Ah, but I can run only 50% discharge, 80-90% peak charge for longer life for most recreational use. I can use full capacity with 2 pair for 32Ah in duty standby for long range. Also provided auxiliary range to my Bosch system, and individually the 6S is a double capacity of the GoE OnWheel friction drive about to deliver from Kickstarter… So these 16Ah are good capacity and versatile across multiple ebike drives. Of the 4 cells I can use 3 for a 72V 16Ah pack in a direct drive hub motor kit as well. A DIY magnetic connector to the Ego battery spades would be handy. I hope the Ego products continue and we get the battery filter down. Like Like

Hey David, I didn’t quite follow but I think you’re using a different battery from the EGO, right? I’m curious about how you wired it into your Bosch system and whether you worried about using a higher voltage battery than the what the 36v Bosch wants? You haven’t figured out a way to use the Cycle Satiator with the stock Bosch battery, have you? Like Like

Here’s the Ego 2Ah to 4Ah to HK 16Ah lunchbox bulk comparison. Like Like

I was just at Home Depot and then checked out their and EGO’s websites. They tend to only carry the package deals in house. If you want a tool w/o battery and charger or just a battery, you have to order online. Does anyone have knowledge of the dimensions of the 7.5 A-hr unit? Like Like

Is there a picture of the bike this battery powers? Mortorcycle, airplane, whatever… let’s fire it up and see what she’ll do. Like Like

I would have never have thought of doing this. Since I was in the market for a battery, I went for the 7.5ah pack, its a really solid high discharge pack. I’m very impressed with it. Thanks for the top tip Karl! Like Like

Thanks Karl! Had just finished modifying a battery box from an ego mower into a battery mount, when my lunagizer went down and I had no way to charge my shark pack. (support has requested a replacement, thanks Louis!) But because of your inspiration I am still motoing! Getting about 4 real good miles, and another 1 1/2 weak miles from a 2ah battery. Got a charger, 3-2ah batts and the batt box for 180 delivered! Not an ideal solution to a spare battery, but it works and was cheap! Oh yea, the reason I went this route is I run a lawn care business and were switching to battery electric on all our small engine machines. Guess which manufacturer we use! Hehehe! Life is grand! Like Like

Forbidden and hidden dangerous goods

Forbidden dangerous goods

The information shown below summarises some common items that are classified as dangerous goods. passengers are forbidden to carry them on an aircraft:

  • Bleach/oven cleaner
  • Butane cartridges, refills/gas bottles
  • Flares/ gunpowder
  • Car/motorbike batteries
  • Party poppers/fireworks
  • Fuel and petrol/oil based paint
  • Gas canister exceeding 28g/50ml
  • Insect sprays
  • Paint stripper/hydrogen peroxide
  • Pepper spray/mace
  • Self balancing devices
  • Sparklers/firelighters

Hidden dangerous goods

Some commonly used items may contain dangerous goods. An indication can be a coloured ‘diamond’ displayed on the item. For a list of some common items refer to our hidden dangerous goods (PDF).

If you are unsure of the product/item/device you want to carry, email Dangerous Goods.

What you can carry and where?

Passengers are permitted to carry certain dangerous goods provided specific requirements are complied with:

  • Allowances are for personal use only.
  • Commercial quantities are not permitted as passenger baggage and must be sent as freight.

Important: It is the responsibility of the passenger to check carriage requirements of dangerous goods, as they may differ from other airlines and countries.

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Dangerous Goods that are not permitted in passenger baggage may be accepted as dangerous goods freight. For information, contact your local Qantas Freight Opens external site office or email Dangerous goods.

cordless, ebike, your, parallel, welding

Things to know

Dangerous Goods Regulations define items that may endanger the safety of passengers or an aircraft as ‘dangerous goods’. These include obvious things such as petrol, butane gas, mace etc.

There are however a number of common items that are considered dangerous goods e.g. aerosols, cigarette lighters, portable battery powered devices, portable medical oxygen etc. These can be carried provided certain requirements have been complied with.

If you’re travelling with powerbanks and spare or loose batteries, please ensure they are packed into your carry-on baggage.

For further information on batteries and battery powered equipment, please view the CASA Safety Video. Travelling Safely with lithium batteries Opens external site in a new window.

Any items carried are for personal use only. Commercial quantities are not permitted as passenger baggage and must be sent as freight.

Further information on dangerous goods

The International Air Transport Association (IATA) Dangerous Goods Regulations describe in detail what Dangerous Goods may be transported by air, in what quantities, and how they should be packed. For details on how to safely transport your Dangerous Goods, contact your local Qantas Freight Opens external site Office.

Important information regarding electronic devices

Qantas Group customers are advised to refer to the Product Safety Opens external site website for a list of products that contain dangerous goods that have been recalled due to faults.

Customers planning to travel with these products should refer to the original manufacturer for further information and recall instructions.

Finishing touches

The only thing left to do at this point is to add the connectors, unless you did that before you soldered the wires on, which I actually recommend doing. But of course I didn’t do that, so I added them at this step, being careful not to short them by connecting only one wire at a time.

You can use any connectors you like. I’m a big fan of Anderson PowerPole connectors for the discharge leads. I used this other connector that I had in my parts bin for the discharge wires. I’m not sure what that type of connector is called, but if someone wants to let me know in the Комментарии и мнения владельцев section then that’d be great!

You can also add a label or other information to the outside of your pack for that professional look. If nothing else, it’s a good idea to at least write on the pack what the voltage and capacity is. Especially if you make multiple custom batteries, that will ensure you never forget what the correct charge voltage for the pack is.

You’ll also want to test out the battery with a fairly light load in the beginning. Try to go for an easy ride on the first few charges, or even better, use a discharger if you have one. I built a custom discharger out of halogen light bulbs. It allows me to fully discharge my batteries at different power levels and measure the output. This specific battery gave 8.54 Ah on its first discharge cycle at a discharge rate of 0.5c, or about 4.4 A. That result is actually pretty good, and equates to an individual average cell capacity of about 2.85 Ah, or 98% of the rated capacity.

Manufacturers usually rate their cells’ capacity at very low discharge rates, sometimes just 0.1c, where the cells perform at their maximum. So don’t be surprised if you’re only getting 95% or so of the advertised capacity of your cells during real world discharges. That’s to be expected. Also, your capacity is likely to go up a bit after the first few charge and discharge cycles as the cells get broken in and balance to one another.

I didn’t include a charging a section in this article, as this was just about how to build a lithium battery. But here’s a video I made showing you how to choose the appropriate charger for your lithium battery.

Now it’s your turn!

Now you’ve got all the info you should need to make your own electric bicycle lithium battery pack. You might still need a few tools, but at least you’ve got the knowledge. Remember to take it slow, plan everything out in advance and enjoy the project. And don’t forget your safety gear!

If you’re like me, then you like hearing and seeing how things are done, not just reading about them. That’s why I also made a video showing all the steps I took here in one single video. The battery I build in this video is not the same exact battery, but it’s similar. It’s a 24V 5.8AH battery for a small, low power ebike. But you can simply add more cells to make a higher voltage or higher capacity pack to fit your own needs. Check out the video below:

I’ll leave you with a little more inspiration

Now I’m sure you’re all jazzed about building your own battery pack. But just in case, I’m going to leave you with an awesome video featuring battery builder Damian Rene of Madrid, Spain building a very large, very professionally constructed 48V 42AH battery pack from 18650 cells. You can read about how he built this battery here. (Also, note in the video his good use of safety equipment!)

About Micah

Micah is a mechanical engineer, tinkerer and husband. He’s spent the better part of a decade working in the electric bicycle industry, and is the author of The Ultimate DIY Ebike Guide. Micah can usually be found riding his electric bicycles around Florida, Tel Aviv, and anywhere else his ebikes wind up.

Комментарии и мнения владельцев

Hello Micah, Thank you for the article! I am currently making a battery for an electronic skateboard, so I need the layout to be as thin as possible to allow ample room underneath the deck. Currently, I have 6 packs of 3 cells welded in parallel, and would eventually like to create a battery which is 9 cells long, 1 wide, and 2 high, for 18 in total (the two packs of nine would then be welded in series). I am wondering if I could be able to make 2 battery packs by welding 3 of my current 3 cell packs together in parallel to make a long, yet skinny pack, and then welding both packs of nine in series using the alternating system. Essentially, I would be creating a pack that would look like 3 of the ones you show above when making your first series connection. Let me know what you think, and thank you!

If you do that (create two 1s9p packs and then weld them in series) you will end up with a 7.4V system. Is that high enough voltage for your needs?

HI Micah, many thank for all the hard work you put into this. After months of trawling through the net, this is by far the easiest and most informative site iv’e seen – Thank you. So after buying a 48v 20 Amp battery from Ebay (and knowing very little at that point), I realized it didn’t have a BMS and heard rumors that if i attached it direct to the controller, it would see it as a short (controller would be closed) and blow the controller. I then bought a “Whale” 48v 17.5 battery with BMS. Question: If put two connectors at the controller end (creating a possible parallel connection) plug in the “Whale” charger at 17.5 Amp and turn it on to pre-load and open the controller, and then on the second parallel connector plug in the 20 amp “Ebay” battery (both “Ebay” and “Whale” are li-ion, 48v but different ampages and cell manufactures: Panasonic and Sanyo). Would the more powerful “Ebay” 20 amp battery blow the “Whale” BMS? I understand that the Ebay battery may run low, but as it is running in parallel to the “Whale”, I’ simply use the “Whale” LED display as rough guid to both batteries charge state (assuming I fully charge both batteries each time before I ride). I simply don’t want to blow the £400 “Whale” battery Thank you

First off: the info you received about a the battery without a BMS blowing your controller is wrong. It’s always a good idea to use a BMS for safety reasons, but as long as the battery is balanced and fully charged, your controller has no idea if it has a BMS or not. All your controller cares about is if the voltage is correct, which as long as the battery is charged, then it presumably will be. Next, regarding your question of paralleling the batteries. Yes, you can parallel them, and you can do it even before connecting to the controller. The biggest safety issue (and damage issue) though is to always be sure they are at the exact same voltage when you connect the two batteries in parallel. The easiest way to do this is only to connect them in parallel when you’re sure they are both fully charged.

Hi Micah, I have built a few 13s lithium batteries in the past year following your instructions. Thanks. I have taken one of the batteries apart to check its condition as it is the middle of winter here in Winnipeg, Canada. Two parallel sets were out of balance with the rest of the pack. I was wondering if there is a way to use my imax b6 balance chargers to rewire the battery and keep each parallel pack in balance for sure! This way I will bypass the bms. Does this make sense?

This makes sense. Yes, it would be possible. You could wire balance connectors and extra discharge plugs to make three packs out of your one 13s pack, such as two 6s packs and a 1s, or two 5s packs and a 3s, etc. Then you’d charge each one, one at at time, using your imax B6 charger. It would take a while, but that’s how you’d do it. Just be careful to not get your connectors confused, as you’ll have three sets of balance wires and three sets of discharge wires.

hello Micah, I finished an ebike yesterday, but i found some major problems on it, The problem is while i riding the bike by throttling, some times the display light dims and low battery voltage caution icon is displaying in the display. and than display shutting off. after that if i try to turn it on again it wont work, so i removed the battery from controller and installed it again than works perfectly, it happens always so i want to remove and install battery again and again, so what is this problem, is this problem is in battery or controller?? Please give me a solution.

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