Ebike amp hours. Ebike amp hours

The Ultimate e-Bike Battery Guide

The commute to work, a Sunday excursion, or the ride to your weekly supermarket visit – for whatever purpose, e-bikes are a reliable, environmentally friendly. and fun alternative to other transportation options. Have you decided to join the e-bike family and have understood all the things to know before your e-bike purchase? Then the next step is digging deeper into e-bike battery 101! E-bike batteries are arguably one of the most important components on your e-bike and choosing the right one is super important for being completely satisfied with your e-bike, as they will define for how long and how far you will be able to ride.

This guide will tell you everything to know about e-bike batteries, as well as tips and tricks for their proper care and maintenance!

Understanding the e.bike terminology

When choosing an e-bike, terms such as volt, amp-hours, and watt will most likely cross your search – understanding and decrypting the meaning of these figures is sometimes more challenging than the actual e-bike choice!

Volt means power and shows how powerful your battery can be. The higher the voltage, the more or the faster energy can be moved – and the more power your bike will have!

ebike, hours

Ampere hour indicates the capacity of the e-bike battery. The higher the amp hours, the greater the battery range and distance you can travel! Also, the higher the degree of a charger’s amperage, the faster the battery can be charged.

Watt ultimately determines how far your e-bike will go. T he greater the number of watt-hours. the more power and the longer the range. The watt-hour depends on a lot of different factors, such as the rider’s weight, the type of riding, temperature, etc.

Choosing the type of battery

Most of today’s e-bikes are equipped with a lithium-ion battery. as they can store a great amount of power while being lightweight. These batteries offer a great range, reliability, and longevity. So, no matter whether you’re pulling a cargo with your kids in the back or are carrying your grocery purchases, your e-bike will support you.

ebike, hours

As a general rule of thumb, it is usually best to get a larger and higher-quality battery. as the last thing you would want is being far from home and suddenly losing power. Keep in mind that all the extra weight that you might need to carry on your e-bike will affect the battery’s power – no matter whether it’s the cargo with your kids, or your heavy backpack filled with the groceries for your family dinner.

The battery is the powerhouse of your e-bike

Defining the lifespan of the e-bike battery

Pinpointing the exact distance your e-bike will be able to go with its battery is almost impossible, as it depends on a variety of factors. Entry-level e-bikes can give about 30-60km, while higher-end brands can range up to 120km on a single charge. The weather, cargo weight, surface, rider weight, and battery age have however the last say in that!

This is why it is recommended to choose an e-bike with a battery that has a slightly larger capacity than ordinarily needed, as you never know which conditions you will face! Like with your phone battery, the performance of the battery will slowly deteriorate throughout the years – investing in an e-bike with a high-quality battery upfront will make your life a lot easier. Lithium-ion batteries are generally definitely built to last and will give you reliable performance for the years to come.

Extending the range of e-bike battery

If you have to conserve the energy of your e-bike and try to go longer distances on a low charge, several tips will extend the range.

As stopping, starting, and braking on your e-bike pulls a lot of energy out of your battery, try to adapt your riding style if necessary. Carrying heavy weight definitely also drains energy! Also, riding on smooth and flat surfaces will extend the e-bike battery range compared to hilly and slow terrain.

Improving the life of the e-bike battery

E-bike batteries degrade over time, but there are several tips and tricks you can follow that will keep your battery in great condition and performance.

Most importantly, you should always handle your battery with care – treat it like it is part of your family! Paying attention and avoiding vibration will limit the chances of a shortened battery life.

Store and charge the battery indoors at room temperature and avoid storing it in direct sunlight – the battery enjoys the shade!

Always make sure to disconnect the battery as soon as it is fully charged.

Your e-bike battery will be damaged if you continuously over-charge it; many e-bikes are equipped with a battery management system, which prevents over-charging and discharging!

Charging your battery

The duration of the charge very much depends on the size of the battery and the quality of the charging cable. Do talk to your local bike shop for choosing the correct charger for your e-bike battery.

The battery can be charged regardless of its current charge level – just remember that batteries have a limited charge cycle, so you should usually not charge the battery at any chance you get!It is also recommended to avoid discharging or emptying the battery completely. Do however try to always recharge after a ride!

Ebike Battery Math: Volts, Amps, Amp Hours, Watt Hours

These days, awesome ebike battery packs constructed of quality 18650 cells are available to average bike builders thanks to advances in 18650 DIY pack building methods and vendors such as Luna Cycle who have begun offering quality affordable packs to kit buyers for the first time.

The battery pack is probably the most expensive component of your ebike, so its best you understand what you are paying for before making a big battery or ebike purchase.

But if you are a newbie, selecting a battery for your new ebike build can be an overwhelming endeavor with all these weird numbers to consider. This guide will attempt to make it easier. Consider Volts, Amps, Amp hours (Ah), and finally Watt hours (Wh) when picking your battery. This article will break them all down. With some simple math you can keep yourself from being ripped off when making a purchase from some slick snake-oil selling ebike vendor. Never have the need to ask how fast or how far it will go again. By using some simple math, you will have an accurate idea of the expected range and power expectancy of any pack.

Volume and Weight

The first one is easy one to quantify because we all have been taught volume and weight since grade school. The girl in the picture holds a 20ah 52 volt battery pack which holds a kilowatt of energy (1000 watt hours) and weighs around 12 pounds. A pack holding that much juice 10 years ago would be made of lead acid and would be heavier than a car battery and we would need a different and much bigger girl to even lift it up.

The most precious commodity we have as ebike builders is space, and. none of us want to carry a lot of weight when we ride because we want our bike to feel like a bike and not some heavy motor bike. How large and how heavy a pack should be is one of your biggest considerations. As technology progresses, ebike packs that can take you many miles are being compressed into smaller sizes and lighter weights, so that now in 2015? even a back-pack battery can take you for a long ride. Look and feel the weight of a battery pack, and decide now what size you can put up with. because its not just the high cost of quality lithium you need to consider. size and weight are also big hurdles to care about.

So. you want your battery pack to be light and small?

You want it to be powerful?

You want it to be safe?

And you want it to be cheap?

Good luck. Elon Musk of Tesla is building an entire “gigafactory” in the desert of Nevada to try to establish all those things. And if his vision is correct it will change battery performance and pricing and actually make it possible to check all the items in the above list.

At the time of this writing you would be lucky to get two of the listed battery pack characteristics, and you are definitely not going to get all 4 items on that list. Although ebike packs have gotten much more power-dense and affordable. we all agree it could get better. For now, buying a battery pack is about compromises. If you want to go far, and you want it to be powerful its gonna be a bit big and heavy. If all you want is cheap and powerful, buy a lead acid pack. If you want light and cheap, go with Hobby King LiPo’s but only if you are knowledgeable, and know the safety risks. Ebike battery buying is all about deciding how big a pack you are gonna put up with to achieve your needs.

Volts

Lets say you got an existing ebike you are trying to revamp with a new 18650-cell battery pack, or you just bought a cheap China ebike kit off eBay, and you’re looking for a battery for it. the first question you need to know is. what is the voltage of your controller and motor?

Picking the wrong voltage battery is the only thing that could do serious damage to your ebike motor and controller if you pick the wrong one. Get the voltage right and you can’t go wrong with the rest.

A 36-volt controller and motor in general requires a 36-volt pack. All controllers allow a range of voltages before they pop so it’s highly probable you could go to a 52-volt battery even though your controller is rated for 48 volts. (read article on the benefits of 52v battery) By overvolting your 48V controller and motor with a 52V battery you get a nice performance gain with a low chance of frying your controller. Upping the voltage of your battery slightly is the easiest way to get a performance gain on an existing electric bike set up.

So once you have the voltage selected, now you have to make one of your biggest decisions. how big do you want your battery to be? How much range do you want? And remember the more range, the larger and heavier the battery.

Amp hours

The 18650 pack above is made up of Pansonic PF cells and is the Tesla S battery pack. It is 85kWh. about 170 tiimes as large as a typical eibke pack. Today ebike builders learn from the technology Tesla is pioneering to make safe and large pack.

The Amp-hour rating is how much energy capacity is in your pack. But the true energy capacity you also need to consider voltage. For example the pack above is for a Tesla and is made up from cells from the the same Panasonic company that Luna Cycles uses. The more Amp hours, the further you will go. But that gigantic pack is only a little more than 200 Amp-hours. Does that mean its only 10x as big as a 20-Ah pack? No. You also need to consider voltage and the above pack is 375 volts. (enough volts to fry chickens). So right here is where it gets a little tricky. you can’t compare pack energy capacity with just the Amp-hours.

Watt hours.

The ebike above is the Juiced Rider which is one of my favorite commercial electric bikes, because it really does have a huge battery pack. I know because I can do the Ebike math. You can buy the Juiced Rider with up to 48V / 32-Ah which is a whopping 1536 Watt hours (1.5 kWh) which (thanks to math) I know this bike could actually have a very real 100-mile range.

However its hard to identify such a spectacular ebike without ebike math because the industry is full of gross exaggerators, and its hard to believe when someone says his ebike he is selling you will take 100 miles on a charge. but the top of the line Juiced Rider is one that really can.

One of the “gotchas” ebike sellers can get you with is to sell you on a high Amp-hour pack, but not tell you its low voltage. For example a 36 volt 10-Ah pack does not have near the range of a 52V / 10-Ah pack. To do a comparison of ranges of two different packs, they must be the same voltage, in which case all you would need is the Amp-hour rating to compare the difference. But. if the two packs are two different voltages then you must calculate Watt-hours.

Watt hours are calculated by multiplying the volts by the Amp-hours. So a 36 volt 10-Ah pack has 360 watt hours and a 52V 10-Ah pack has 520 watt hours. (read our article on calculating range) Once you get to 1000 watt hours, its called one-kilowatt-hour, and that’s how electric car packs are measured. Most ebike packs do not get too far over a kilowatt-hour because now, just the pack is going to weigh over 20 pounds and you start leaving bicycle range. Once you know how to calculate watt hours you can fairly well know what you are paying for in a battery pack. Now we get to the fun part. deciding on how much power we want!

AMPS-

This is the power rating of the pack. how much power it will put out. If you multiply the amps by the volts you will get the wattage your battery is capable of. For example, a 30-amp 52 volt pack is capable of 1500 watts plus. In general you probably want to choose a higher amperage battery over a lower amp battery. You can’t burn out your controller with a high amperage battery because your low amp controller will just suck whatever amps out of it that it needs. If you get a battery rated for low amps. your controller might not get all the amps it wants, which will just mean you will go slower so no harm is done. But if you want maximum speed and power that your set-up is capable of, you want a battery that is rated for at least as high amps as your controller is rated for. If you want to be future proof get an even higher amp-capable battery pack than what your controller is rated for, in case you upgrade the controller, or some day build (or buy) a more powerful ebike.

Tools for Measuring the above numbers

There are several great measuring devices to keep everyone honest when it comes to getting the amp hours you paid for etc. The 30 Watt Meter is a very inexpensive way to measure amp hours in a pack and so is the 135 Cycle Analyst. These devices measure the energy as its depleting from the pack and act like a very accurate fuel guage which tells you exactly when your bike will run out of juice and then you can easily calculate how efficient you and your bike are. Why do no ebike manufacturers provide these convenient gadgets on their bike? They do not want you to have an accurate Amp-hour guage. guess why?

Charging Math

OK, so now what about charging? Are you getting a fast charger or a slow charger? How long will it take to Charge your battery? Well that’s an easy one. You need to pick a Smart charger that is compatible with your batteries chemistry and the voltage of your battery. Charging with the wrong voltage or wrong type of charger is a fire risk and should never be done.

If you divide the amp hour rating of your battery by the amp rating of your charger, that is how long it will take you to fully charge your battery. However, all good lithium Smart chargers dial back the charge at the end of the charge cycle, so they take a little longer than what they are rated for. So for a 10 Amp-hour battery it will take a 5-amp charger a little more than 2 hours to charge your pack. With a 1-amp charger it will take 10 hours. The larger the battery, the safer it is to charge at high amps. For example, charging at 5 amps is fast for a 10 Amp-hour battery, but. not so fast for a 20 Amp-hour battery. When you charge your battery fast, all the time it will greatly reduce your batteries life expectancy. We recommend you stick to slow charging (4 hours or more) or go with a charger that can switch between fast and slow charges like the Luna Charger.

Now, if you have a 10-Ah battery and you have a 5-amp charger. that is a super fast charger for that pack. One way you can tell is if when charging, does your pack get warm. if it gets fairly warm, you are degrading the life of your cells, and its time to invest in a slow charger.

Ebike Math; Now You Got it

Now do the ebike math. which pack is bigger? Its all about math. not guesses on how far your pack will take you. A Sondors Ebike pack is 36 volts 9-Ah, so it contains 324 watt hours and based on that, you can guess how far the pack is going to take you. If you ask Sondors how far his pack will take you he has to exaggerate his mileage number because that is how the ebike industry has been doing it for years and its hard to compete with a bunch of exaggerators by suddenly being honest. Its a dumb question to ask an ebike salesman how far his bike will go. if you ask a dumb question expect an exaggerated dumb answer.

So once you have all these numbers down you have the basic knowledge on how to compare packs based on real numbers. and you will never again ask “how far will it go” or “how fast will it go” because you will have math to back you up. and know exactly what you are paying for when buying an ebike (or ebike battery).

End of Story

I will give you one great example to end this story of how ebike math could possibly save you big bucks. Recently, one of my Luna Cycle customers went into a Arizona dealers shop with two of my 52V 20-Ah triangle packs. Happy with the amazing deal he got on the Luna pack (700 each for over 1000 watt hours). He was doing good, but his mistake was going into this gigantic dealers shop with super inflated snake oil pricing, thinking he could get a cheap battery install. The dealer convinced him that the 52 volts might burn out his “E-rad Bafang” so the warranty would not be covered. not true! the Bafang BBS02 (it’s proper name) is rated to handle safely a 52 volt battery.

So the dealer sells him on a “E-Rad”48V 10-Ah pack inside of a sexy dolphin case with a price tag of 1000 that will give him “50 miles plus” range. The dealer convinces him that the 1000 watt hour Luna Cycle battery is big and bulky and will give him half the range of the dealer’s 1000 400 watt hour pack. The customer eats a high hazmat charge to ship two perfectly good Luna Cycle packs back to Luna Cycle. Luna Cycle accepts the return, thinking karma will pay at the end. obviously this is different than typical ebike exaggerating. this is an example of a dealer lying to a customer. No ebike sales man could honeslty argue his half sized pack will get double the range of a full sized real pack.

So, if this customer knew ebike math he would have no problem calculating that he was being bamboozled. There is no way a 400 watt hour battery is going to double the range of a 1000 watt hour battery no matter what snake oil it is filled with. And if the customer believed that Luna was making up its amp hour rating he could easily get a watt meter and test the battery himself and know which dealer is BS-ing and which one is the real deal.

Luna Cycle decided to one up the dealer. and now has the same sexy slim dolphin cased battery with better cells that dealer sold for 1000 at less than half the price (420) and the Luna pack stacks 648 watt hours into the same case because we use better and more power-dense cells. (Panasonic NCR-B). We also one-upped the dealer by re-designing the pack to fit more cells, and more watt hours, and offering a 52V 13.5-Ah version which has over 700 watt hours.

Luna Cycles “Shark” Pack

But no matter how sexy that ebike battery looks (actually it kind of looks like a dildo) Never judge a battery pack by the cover. use math to figure out watt hours and even figure out how much each battery cost per watt hour. Use testing equipment to verify you got the battery you paid for.

But its not just about Math and raw numbers. Next comes Chemistry. Quality power-dense cells like the Panasonic NCR-B or high amperage cells like the Samsung 25R have the bleeding edge chemistry and can be twice as expensive as other Samsung or Panasonic cells. Chinese cells are super cheap, but ineffective because they haven’t figured out yet how to make decent chemistry.

But, to get that amazing energy density which is watt hours to size and weight. you are going to need to pay for top quality name-brand cells using the best chemistry.

But 18650 chemistry is a different story for a different day.

Written by Eric, December 2015

Electric Bike Voltage And Watts. Helpful Guide To E-bike Power

When you are looking at electric bikes there is a lot of new terminologies you aren’t used to seeing. What do electric bike voltage, amps, and watts mean? Will a 48volt e-bike go much faster than a 36volt e-bike? What about a 1000 watt e-bike versus a 500 watt e-bike? Let’s take a look at some basics of electric bike power systems to clear up all the confusion.

Electric Bike Voltage, Amps and Watts. What do they mean?

Volts, Amps and Watts are the units electricity. Volts are pressure, Amps are volume and Watts are power.

What is a volt?

Volts are a measure of electric potential. Think of them as water pressure in a hose. The higher the voltage, the higher the pressure of the electrons flowing in a circuit.

What is an Amp?

Amps are a measure of electric current. This is the volume of electrons flowing in a circuit. Think of this as the same as how much water is flowing in a hose. A fire hose has a much higher volume of water flowing through it than a 1 inch garden hose. A 50 amp circuit has many more electrons flowing through it than a 10 amp circuit.

You can only push so much water through a hose before a hose will burst. In a similar manner, you can only push so many electrons through a piece of wire before the wire burns up. Circuits and wiring have a maximum amount of current they can handle before overheating and burning up. Circuit breakers and fuses are put in the circuits to prevent damage from over current. This is why you should never replace a fuse with a higher amp fuse if that’s all you have available.

What is a Watt?

A Watt is a unit of power similar to Horsepower. 745.7 Watts are equal to 1 HP. Your 300hp internal combustion car engine is also a 223,710 watt engine. Watts is equal to Volts Amps. A 36volt bike pulling 20 amps is producing 720 watts of power.

  • A 250 watt e-bike is a 0.33 horsepower e-bike
  • A 500 watt e-bike is a 0.67 horsepower e-bike
  • A 750 watt e-bike is a 1 horsepower e-bike
  • A 1000 watt e-bike is a 1.34 horsepower e-bike

If you have a high voltage but really low current it is like having a very thin stream of high pressure water. It’s not going to push anything. If you have very low voltage and high amps it is like a 6 inch pipe with water trickling out. It won’t push anything out of the way. If you have high voltage and high amps you will have very high watts. This is similar to a fire hose opened full blast. You can use that water to blast anything out of your way. With an electric bike more watts is more power. power will be more fun.

For reference a professional cyclists can produce a sustained 400 watts of power from their body and can generate 1000 watts in short bursts. A 500 watt e-bike is giving you a professional cyclist amount of pedal assist. To learn more about human power output go here.

The below video shows an analogy between water/hydraulic systems and electric systems to make it easier to understand.

Doug RyanCo-Founder Biking Editor

I have been riding bikes and messing with them my entire life. I have always loved the thrill of riding whether it’s down the street or in the woods on a trail. I have a Master’s Degree in Mechanical Engineering and Reliability and am a complete gear nerd. I have 20 years of product development engineering experience and a lot more years of biking. I currently reside in Michigan but grew up in Pennsylvania.

How to understand ebike and escooter battery specs

Napier Lopez is a writer based in New York City. He’s interested in all things tech, science, and photography related, and likes to yo-yo in (show all) Napier Lopez is a writer based in New York City. He’s interested in all things tech, science, and photography related, and likes to yo-yo in his free time. Follow him on

If you’re shopping for your first ebike or electric scooter, you might be a bit confused by the numbers you see on the spec sheet. What exactly is a watt-hour (Wh), and how is it different from an amp-hour (Ah)? Does voltage matter? How big of a battery do I really need?

With the help of some basic physics and arithmetic, we’re here to help you make sense of these numbers.

Which spec tells me the battery capacity?

When you look up an electric bike or escooter, chances are you’ll come across a variety of numbers related to the battery. These three are the most common ones: volts, amp-hours, and watt-hours.

Watt-hours (again, that’s ‘Wh’) are the most useful unit when it comes to energy capacity. If you’re looking to compare the battery sizes for two rides, you’ll want to look for the watt-hour rating on the spec sheet.

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But there might be some last-minute spots available

Assuming honest specifications, the bigger the watt-hour rating, the bigger the battery — longer the range.

I don’t see a watt-hour rating, only amp-hours and volts. Help!

While most ebike companies these days show battery ratings in watt-hours, many electric scooter companies still stick to volts and amp-hours. Worry not, my friend. Finding a battery’s watt-hour rating from volts and amp-hours is the simplest of multiplications. Here’s the formula for you:

That’s it. By the same token, you can find a battery’s amp-hour rating by dividing the watt-hour rating by the voltage. Or divide the watt-hours by amp-hours to find the voltage.

Keep in mind the above formula is an approximation, as a battery’s voltage will vary during use. But for all intents and purposes, it’s the easiest way to compare battery capacity among various ebikes and escooters.

The ebike I’m looking at has a 250W motor. How does that relate to range?

The motor’s wattage on its own doesn’t tell you anything about the range. Although they are related, watts are distinct from watt-hours.

The former is a unit of power. When it comes to ebikes and escooters, that basically means how much power the ebike is able to draw from your battery over an extended period of time.

A higher-wattage motor higher-wattage motor can theoretically go faster or climb up steep hills for longer. It will also drain your battery faster at its maximum demand, but a motor’s wattage isn’t a fixed value — it depends on how hard you are pushing the motor. The figures given by manufacturers are averages.

The watt-hour, on the other hand, is a unit of energy (or energy storage). It basically tells you what sustained wattage is required to drain the battery in the span of — you guessed it — an hour.

In other words, if your motor is using an average of 250W, it would take about one hour to drain a 250Wh battery, two hours to drain a 500Wh battery, and so on.

But again, you shouldn’t rely on watts to estimate range because the motor’s wattage is rarely constant. They usually can ramp up to wattages beyond their official rating; that’s why you’ll see some companies list their “peak wattage” along with the standard or “nominal” wattage.

How big is big?

As we’ve noted, the amount of energy used by a motor can vary significantly, but there are some general guidelines you can keep in mind.

Typical ebike and scooter batteries tend to hover around the 400-600Wh mark. Lightweight scooters and ebikes tend to be closer to the 300Wh mark, while heavier, powerful models tend to be closer to 1000Wh — or more.

How far those batteries will take you depends largely on how you use your bike or scooter. Higher assist or speed settings will naturally use more energy, but things like the type of motors, wheels, or sensors can affect range as well.

Lots of talk about watts, but what about volts and amp-hours?

For most people, knowing the watt-hour rating says everything you need to know about an electric vehicle’s battery capacity. Still, you might be curious how volts and amp-hours come into play. It can be a little confusing, so keep in mind the following is all a simplification.

The most common voltages on the market these days are 36V, 48V, and 52V, although you’ll occasionally see lower or higher ratings too (the latter especially in the DIY market). All else being equal, a higher voltage battery will usually be able to output higher power and maintain high performance at low battery levels.

Higher voltage batteries will also use less current at a fixed power rating, which theoretically translates to less heat and damage to the motor for a given performance level. On the other hand, higher voltages can technically increase the risk of electrocution. That’s partly why you rarely see commercial ebikes go beyond 52V.

As with so many facets of technology, the implementation often matters more than the actual specs. Some of the best hill-climbing ebikes I’ve tested have used 36V motors, while I’ve had weaker pedaling experiences out of some 48V ebikes. In my experience higher voltage batteries are usually better than lower voltage ones.

Despite remaining a common specification, amp-hours is frankly a pretty useless metric for most ebike and scooter riders.

Although it is typically used to denote battery capacity, it should only be used for comparison on ebikes with identical voltages. A 24V 20Ah battery will have significantly less range than a 52V 15Ah one.

If you want to know an electric bike or scooter’s realistic range, looking at the watt-hours is still your best bet.

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