Whether you power your ride for commuting, adventure, leisure or e-cargo, your electric bike battery is the beating heart of your trusty steed. So knowing how to look after it is crucial to keeping your e-bike riding smoothly (and safely) for longer.
E-bike batteries come in a range of different shapes, sizes, fittings and power outputs (typically 36V or 48V), depending on the style of your bike.
The battery lifespan (how long it’ll last before needing replacing), and range (how long it’ll power each ride per charge cycle), depends on its material, overall use and ongoing maintenance.
In this guide, we share everything you need to know about batteries for electric bikes, including typical lifespan and optimisation; where to recycle; and the question on every powered rider’s lips: is it safe to leave your e-bike battery on charge overnight?
Disclaimer: This blog is intended as general advice for e-bike owners. For specific maintenance advice on batteries for electric bikes, please consult your user manual or a professional.
How long do electric bike batteries last?
Battery life is measured in charge cycles. Most batteries for modern electric bikes use lithium-ion technology, with a typical lifespan between 500 to 1000 full charge cycles.
If we’re talking years, that’s around three to five, though some will last up to eight years if you always keep your e-bike partially charged to spread the full charge cycles across multiple rides.
What counts as a charge cycle?
A charge cycle is when you use all of your e-bike battery’s power (i.e. 100%). The thing to remember is that one full charge cycle can happen across multiple charging sessions.
For example, if you went for a ride that depleted your battery from 100% to 50% and you charged it back to full, that’s half a cycle.
If you then did the same thing the next day, that would total one charge cycle, not two – because you’ve used 100% of your battery’s available power.
Similarly, if you depleted your battery from 100% to zero on a ride and charged it back to full, that’s also a single charge (though this is not recommended, to preserve your e-bike battery’s capacity).
So with this in mind, it’s easier to see how a typical lifespan of upto 1000 full charges can last three to five years, if not more, depending on how much you ride and how you manage the charging of your e-bike.
It’s worth noting that a lithium battery’s capacity (i.e. the amount of charge it can hold) will gradually reduce over time. That’s with every charge cycle, and also when not in use, just like the battery in your mobile phone does.
Top tip: Keep your electric bike battery partially charged to around 60-80% to extend battery life and get more rides out of a full charge cycle.
How long will an e-bike battery last on a single charge?
Several factors will affect your electric bike’s battery range.
The bike’s motor and pedal-assist level being used; whether hilly or flat terrain; the rider weight and riding style, and even hot or cold weather can all have an impact on how fast the battery drains.
The voltage on your e-bike battery will also determine how long it lasts.
Most electric bikes come fitted with either 36V or 48V batteries, with the higher voltage drawing more power from the battery to the motor for increased torque and faster acceleration.
This is particularly useful for e-mtb riders, for quick power surges to drive the bike over roots, rocks and hilly terrain.
A 36V e-bike battery has an average range of 20-40 miles, whilst a 48V battery can carry riders up to 40-75 miles – but whether either battery reaches the top of its range depends predominantly on rider weight and what’s being carried on the bike, along with the terrain and pedal-assist mode.
Top tip: Using the lower power assist mode is a good way to make the battery last longer while riding. Not only will you use less juice, it’ll be a good workout too!
Why is my e-bike battery draining so fast?
Leaving your e-bike plugged in all the time can damage the lithium-ion cells in the battery, reducing its full capacity and ability to hold charge.
This is also true for the undercharging too (or over-discharging) – letting the battery run down for long periods of time without use has the same effect.
The average time needed to charge an e-bike battery is between three to six hours to reach full capacity, with a reduced time if the battery is already partially charged.
Most modern e-bikes are equipped with smart batteries which prevent overcharging, but it’s still not recommended to plug in for longer than is necessary.
Overcharging happens when your battery is charged beyond its capacity, putting it at risk of overheating or even catching fire.
Monitor battery health in your app and keep an eye on your battery when it’s charging. If you notice it feels hot to touch or the charge level doesn’t increase when plugged in, consult your manufacturer’s manual or local bike shop for safety advice.
Top tip: Get into the habit of charging the battery for your e-bike after every ride and avoid letting the battery drop below 30% charge to prolong its lifespan.
How to charge your electric bike battery safely
According to the London Fire Brigade, fires caused by lithium batteries are the biggest growing fire risk in London. The service reported an average of one call out for e-bike and scooter fires every two days during 2023.
Follow these steps to ensure safe charging:
- Never leave your battery on charge overnight or when you’re not at home.
- Choose a safe place to charge your e-bike battery: don’t block exits.
- The battery for your e-bike will come with a specific charger – only ever use this one and not another charger for a different device with the same fixture. Apart from the risk of it damaging your e-bike battery and causing a fire, it could also invalidate your manufacturer’s warranty.
- Be vigilant for warning signs that your battery is failing and becoming a fire risk (overheating, not charging when plugged in).
- Leave your battery to cool before charging.
- Set a timer to avoid overcharging and unplug your charger once the battery has charged.
- Fit smoke alarms near to where you charge the battery for your electric bike.
Top tip: To prevent overcharging and reduce fire risk, never leave your battery plugged in for prolonged periods or unattended.
When to replace your electric bike battery
As long as you look after it, the likelihood is your e-bike will outlive the battery that powers it. And that’s OK, because e-bike batteries are replaceable, and recyclable.
Depending on its use and performance, a battery for an electric bike typically needs replacing every three to five years. Use your e-bike display system or app to monitor and optimise battery health so you know when it’s time for a new one.
Electrical Safety First’s Battery Breakdown report cites three main reasons for e-bike batteries to fail:
- Electrical fault – usually overcharging or over-discharge, using faulty or using incorrect chargers, external short-circuit or ingress of water causing short-circuit.
- Mechanical fault – physical crushing or repeated impact to the battery, such as striking a kerb or dropping something onto it while charging.
- Thermal issue – exposure to extreme hot or cold temperatures.
Signs of damage to look out for:
- The battery is draining quickly even when fully charged.
- Sudden drops or fluctuations in power when riding.
- Error codes or battery warning lights displayed on your e-bike.
- Overheating of the battery when plugged in or riding.
- Physical damage to the battery itself. Check your e-bike insurance for accidental damage cover.
In the UK, you can buy replacement batteries for electric bikes at various retailers.
We would recommend contacting your manufacturer or local bike shop for advice before purchasing anything to make sure the new battery meets UK safety regulations and is fully compatible for your e-bike.
Top tip: Make sure the area where you store and charge your e-bike battery is between 5ºC and 20ºC for optimum performance.
What to do with your old electric bike battery
When your battery has reached the end of its life, don’t throw it away, recycle it! If a lithium e-bike battery makes it to landfill it will decay and leak chemicals into the soil with significant risk of chemical burns or fire.
Electrical Safety First’s Battery Breakdown report cites 201 waste fires every year are caused by lithium-ion batteries in landfill (48% of all waste fires).
E-bike manufacturers are legally required to safely dispose of electric bike batteries, and hundreds of bike shops across the UK offer take-back services to recycle old batteries safely.
In 2023, the Bicycle Association announced the trial of a UK-wide e-bike battery collection and recycling service, in partnership with the European Recycling Platform UK (ERP UK). National roll-out is expected in July this year (2024), with 500 retailers expected to form a national collection network.
Velorim also has partnerships with over 600 bike shops in the UK, recycling inner tubes, tyres and now e-bike batteries with its Velorim Recover service.
Ask your local bike shop if they’re part of this or the Bike Association’s recycling scheme, or contact your manufacturer for advice on how to recycle your electric bike battery.
Need help protecting your e-bike? We’re here to help
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