Ultimate Guide: Electric Bike Battery Selection

If you own an electric bike, you owe it to yourself (and your bike) to kit it out with the best possible battery. Choose the correct battery, and not only will the electric motor function better, but you’ll be able to travel for longer on a single charge.

Battery technology is evolving at an incredibly fast rate. There are batteries on the market now that would have been just a technological pipedream a few years ago. So, if you’re looking for a brand-new battery for your electric bike, you’re going to be spoiled for choice.

This guide is going to help you navigate through the myriad of electric bike battery options you have. The information here is essential for those who are looking to buy a new electric bike and want to know what type of battery they’re spending their hard-earned cash on. This information will also be handy for those who are looking to pick up a new battery for a current bike. Although, as you’ll see a bit later, you have far fewer options available to you in that case.

Not content to just give you advice on choosing the right battery for your electric bike, we’re going to wrap up with a few tips and tricks to ensure that you can squeeze every bit of power out of whatever battery you do end up picking up.

Let’s jump in!

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Battery Types for Electric Bikes

Before we share a bit more information about battery specs, we want to share a bit of information about the battery tech you’ll encounter. The battery tech should give you a solid idea of how decent the battery will be, its weight, how it performs, when you need to charge it, etc.

Lead-acid Electric Bike Batteries (SLA)

These are the cheapest batteries that money can buy, and you’ll often find them on the bargain-basement e-bikes. They are heavy, and they don’t really perform all that well. SLA batteries are only really good for those that are saving money.

You should also remember that SLA batteries have the ‘memory effect’. If you don’t properly discharge them before you charge them again, you’ll be killing the capacity of the battery.

Nickel-cadmium (NiCd) Electric Bike Batteries

NiCd batteries are slowly dying out, so you may not see them around too much nowadays, particularly on e-bikes. However, they are somewhat of a step up from SLA batteries. They have higher capacities and they are slightly lighter. However, they’ll still suffer from the dreaded ‘memory effect’ that plagues the SLAs. Avoid NiCd batteries wherever possible.

Nickel-metal Hydride (NiMH) Electric Bike Batteries

Up from NiCd batteries, you have NiMh. These batteries are lighter and with high capacity. They can often deliver a bit more power too. Not to mention the fact that they are quicker to charge. Although, you won’t find them around in e-bikes all that much.

NiMH batteries don’t suffer from the ‘memory effect’, and they retain their charge well, even when in storage. They are probably the best ‘cheap’ batteries you can get. But, honestly, we would highly recommend that you spend a little bit more and get the next battery type on our list.

Lithium-ion (Li-ion) Electric Bike Batteries

Lithium battery tech is dominating the battery industry right now, and not just when it comes to e-bikes. Lithium batteries are the go-to power source for many rechargeable products. Li-ion is the cheapest lithium battery that you can buy. They have high capacity and don’t have the memory effect.

However, once you start getting into Lithium-ion tech, and this applies to all the batteries that follow too, you’re going to have to think longer and harder about whether the battery will actually fit your e-bike. With lithium batteries, bikes can become very ‘specific’ about what they want. This is because special circuitry is needed to handle the lithium battery.

Lithium-ion Polymer (Li-pol) Electric Bike Batteries

Litiium-ion Polymer batteries are a rather cool addition to e-bikes. They have broadly the same advantages as Li-Ion batteries e.g. increased power capacity, and retain their charge well. However, Lithium-ion Polymer batteries have another major advantage – they are liquid. Well, the inside of the battery is liquid. This means that they do not need as much protection as other batteries which, theoretically, reduces their weight. It also means that they can put up with a few extra bumps during the intense periods of cycling.

Lithium Cobalt (LCO) Electric Bike Batteries

Lithium Cobalt batteries are rare, but companies that offer Lithium Cobalt batteries claim that they have high power density and a lighter weight. You’ll rarely find them available for e-bikes.

Lithium Manganese (LiMg204) Electric Bike Batteries

These batteries are much the same as LCO. Rare on e-bikes, but when they are sold, they’ll be high in capacity and low in weight.

Other Things You Need to Know When Choosing an Electric Bike Battery

Knowing the available battery tech is all well and good, but there are three incredibly important things that you should think about when picking up a battery. It doesn’t matter what type of battery you buy, you’ll always need to think about:

The capacity of the battery
The voltage of the battery
Whether the battery actually fits your bike.

Let’s explain.

Battery Capacity (Ah)

Battery capacity is everything when it comes to electric bike batteries. The longer the battery life, the further you’ll be able to ride without charging the battery. So, how do you work out what the capacity of a battery is? Simple! You look at the Ah rating on the battery.

Amp-hours, Ah for short, tells you what the capacity of the battery is. It tells you exactly how many amps the battery has the ability to deliver in an hour. So, if you have a battery rated for 150 Ah, it means that the battery will deliver 150A per hour.

If you look through the manual for your bike (or even the spec online, if you have yet to pick up an electric bike), you’ll find out how many amps per hour the bike needs. Once you know this, you’ll know exactly how long the battery will last. For example – if an electric bike requires 75A to run for an hour, a 150 Ah battery would last two hours.

Now, you may think that it would be wise to go for the highest Ah battery you can afford, right? Well, we don’t blame you. It would make sense. However, don’t. There are two issues with picking up a high Ah battery:

Cost
Weight

The higher the Ah, the heavier it will be. Obviously, you don’t want to be lugging around an incredibly heavy battery, particularly if you are traveling off-road. It is a hindrance. The cost is also going to be a huge issue.

If you only do short rides, you are better off investing in a lower Ah battery. If you’re a fan of the longer rides, then pick up a higher Ah, just bear in mind that it’ll cost you a lot more, and it may be worth looking into whether you can follow the techniques we share to save battery life rather than spend hefty sums of cash.

Battery Voltage (V)

The battery voltage is the amount of power that the battery delivers to the motor. The higher the voltage, the more power is delivered. In theory, the higher the voltage, the faster you’ll go (and your bike will find it easier to tackle tougher sections of a route). Although, that’s the theory.

In reality, the motor on your bike is going to be rated for a certain voltage. Giving it more power isn’t going to magically make your bike go faster. Your bike may accept multiple different voltage batteries, and the higher voltage listed in the spec may give you a fractional boost, though. A lot of this is going to be on the bike rather than the battery voltage that you choose.

What we will point out, however, is that different battery voltages work for different types of cycling. So, if you look at the voltage of a battery when you are buying a bike, it should give you a decent idea of the aim of that bike:

24V batteries are for bikes designed for casual riding, and rarely tackling hills. They thrive best on flat surfaces. A small incline may cause the bike to struggle.
36V batteries are a bit more powerful than 24V. They are still, mostly, for relaxed flat surface cycling, but you may be able to tackle the odd hill with them.
48V is for road cyclists who may be tackling hills frequently. They can also tackle some light off-roading.
52V is a battery that can allow a bike to operate at high speeds and makes off-roading and hill climbing easy.
72V batteries are not something that anybody really needs. They’re good, but they are for the most extreme off-road rides. They’re way too expensive for regular use.

It is important to note that you should only buy a high-voltage battery if you need it. Don’t buy a high-voltage battery for the sake of it. The higher the voltage, the more expensive. They’ll also drain faster and take a whole lot longer to charge.

Does It Fit Your Bike?

If you already own an e-bike, don’t go and blindly buy a battery. That wouldn’t work. Instead, you need to buy a battery that fits your bike. This means thinking about:

Whether the bike’s motor works with your selected voltage
Whether the battery connects up to your electric bike properly.
Whether the battery’s motor works with the selected battery tech (sometimes they don’t).

The only way you can really work out whether your e-bike and the battery are compatible will be to look at both the spec of the e-bike, as well as the battery shape/type on the e-bike, and then compare that to the batteries that you are eyeing up.

Getting the Most Out Of Your Electric Bike Battery

So, now you know a bit more about choosing the right e-bike battery, let’s tell you how you can get the most life out of your battery’s charge. We have a few tips to share with you here!

Understand the Battery Tech

It is important that you know what battery tech you have in your battery e.g. whether it is NiMH, NiCD, Li-Ion, etc. (remember those battery techs from earlier?) this is because it will give you a solid idea of your battery charging habits.

If you have a NiCD battery (or an SLA), then it is important that you do not put the battery on charge if it still has a decent amount of life left in it (over 20%). This is because these batteries suffer from the ‘memory effect’. If you never drain the battery before you charge them, it’ll start to remember this and the capacity that you start charging the battery at will become the new minimum. We know this may seem complicated, but this is how it works:

You put a NiCD battery on the charger when it has 50% battery left.
It charges
You repeat the process.
Eventually, that battery will ‘think’ that it is fully drained at 50% and stop working. So, you would have effectively reduced the battery capacity by 50%.

This is less important when it comes to NiMH batteries and later battery tech, but it is still important that you establish decent charging habits.

Don’t Fully Discharge Your Battery

It is essential that you never fully discharge your battery before charging. This impacts the number of recharge cycles you have (the number of times you can recharge that battery throughout its lifespan). A full discharge puts a lot of strain on a battery.

While it does depend on the battery tech, in an ideal world, you’ll be putting a battery on charge when it has about 20% life left. Every so often, it is fine if it drains fully before you charge it. However, don’t make this a habit.

Store the Battery Partially Charged

If you are putting the battery into long-term storage, it is highly recommended that you store it partially charged. 40% seems to be about the sweet spot here.

Use Minimal Assist on Your Bike

When you are cycling, use the smallest amount of pedal assist that you need. The higher the pedal assist setting, the faster the battery will drain.

Ideally, you would have a low pedal assist for most of your ride. You’ll only want to crank it up a few notches if you need some additional speed, or if you are climbing a hill.

Keeping tabs on your pedal assist settings is a fantastic way to extend the life of a battery between charges.

Get the Right Pressure For Your Tires

The wrong tire pressure can cause drag when you are cycling. This means that the bike’s motor needs to work a little bit harder to move you forward. If the motor needs to work harder, the battery will drain quickly.

We suggest you read through your e-bike’s manual to know the correct tire pressure for the tires. Maintain that pressure.

Don’t Stop and Go

Constant cycling will drain the battery far slower than stopping and going. So, you’ll probably get through a battery charge quicker if you’re cycling through a city (where you need to stop at lights), than if you were on a long path with no obstacles in the way. So, you may want to think about your route a little bit.

Work On Your Riding Cadence

Your cycling cadence is the amount of times you turn your vehicle’s pedals per minute. Ideally, you want somewhere between 70 RPM and 100 RPM. You can adjust the pedal assist settings to suit. Anything less than this, and the motor will need to work harder to get you moving forward which, once again, will drain the battery fast.

Keep the Battery at the Right Temperature

Extreme heat or cold is never going to be good for a battery. So, if the weather is extreme outside, you may want to think about whether you really need to cycle.

It is also important that batteries are not stored outside when the weather is extreme e.g. don’t store an electric bike battery in the garage if it is snowing, or if there is a heatwave. It could potentially ‘kill’ the battery.

Maintain Your Bike

Finally – maintain your bike. Keep tabs on the brake pads, tires, etc. Any excess wear can result in the motor needing to work extra hard to keep you moving.

Final Thoughts

As you can see – there are a few things to think about when you are choosing the right e-bike battery. However, even when you have the right e-bike battery in your hands, it doesn’t mean that you are home and dry. You still need to think about your cycling habits, and battery maintenance, to ensure that you not only have the highest cycling range from the battery, but also the longest battery lifespan. You don’t want to be replacing your batteries too frequently, after all. They’re expensive.

Reference Sources

RIDEL Bikes LLC: https://ridelbikes.com/blogs/blog/electric-bicycle-batteries-explained
Bafang: https://www.e-bafang.com/ebike-battery-voltage/
Electric Bike Blog: https://electricbikeblog.com/electric-bike-batteries/

How To Choose The Right E-Bike Battery And Get The Most Out Of It: A Comprehensive Guide (2024)