The ebike battery is a crucial part of any electric bike, determining motor performance, power output and range.
The battery's weight and where it’s mounted also has an impact on your bike’s handling.
In this article, we’ll look at the different types of ebike batteries and how to care for them, as well as examining battery capacity, storage and recycling.
What types of ebike batteries are there?
Lithium-ion (Li-ion) batteries
Lithium-ion batteries are used widely in modern ebikes due to their high energy density, lightweight construction and long cycle life.
There are several variations within the Li-ion category, such as cobalt manganese blends. Each offers slight trade-offs in terms of energy density and cost.
Nickel-metal hydride (NiMH) batteries
Nickel-metal Hydride batteries were once popular in ebikes but have largely been surpassed by Li-ion technology. They offer lower energy density and shorter life cycles compared to Li-ion batteries but may still be found in some entry-level ebike models.
Lead acid batteries
Lead acid batteries were featured in some of the very first ebikes. However, they are very heavy and have low energy density.
Because of these shortcomings, they were quickly replaced by NiMH and Li-ion batteries.
What are watt-hours? Ebike battery capacity explained
The capacity of an ebike battery is measured in watt-hours (Wh), which indicates the amount of energy the battery can store.
The higher the Wh rating, the higher the battery capacity.
More capacity also equals more weight, with batteries usually weighing between 650g and 1kg for every 100Wh of capacity.
Common battery sizes include 400Wh, 500Wh and 625Wh. Some of the latest electric mountain bikes boast even higher-capacity batteries, with integrated batteries reaching up to 800Wh capacity.
Lightweight ebikes, with battery capacities ranging from 250 to 400Wh, are becoming increasingly popular among mountain bikers and commuters.
Many brands also offer so-called range extenders, which are especially common on lightweight eMTBs but also found on electric commuters and e-road bikes.
These smaller batteries have around 150Wh to 250Wh capacity and are often mounted to the frame where you would fit a bottle cage.
What battery capacity do I need?
How much capacity you need depends on the distance you wish to cover and the terrain you will be riding on. Other factors, such as how regularly you can charge your battery (if you'll be riding consecutive days without a charge, for example) are also important to consider.
If you use your ebike to commute on paved roads or cycle paths with slick hybrid tyres, you will likely be well served by a battery on the lower end of the capacity scale – around 400-500Wh.
However, if you want your bike to be capable of several days of commuting without having to recharge its battery, you will be better off with a larger one.
For riding an ebike off-road, racking up elevation on soft ground with grippy mountain bike tyres, a higher-capacity system (625 to 800Wh) is advisable.
How many miles will I get from my ebike battery?
There’s no exact formula for calculating how much range you will get from your battery because several external factors influence this.
Rider weight, terrain, the assistance level used, riding style – including how effectively you use your gears – and weather all impact the range of an ebike battery.
How to charge ebike batteries
Ebike batteries will degrade very slowly over time, but following the tips below will help you maximise the life of your battery.
- Charge your battery to a high level after each use (where possible).
- Don’t leave your battery empty or with a low charge for extended periods.
- Always use an approved charger.
- Unplug your battery once it has charged fully.
- Follow the manufacturer’s advice for long-term storage.
Don’t leave your ebike battery unattended for long periods (overnight, for example) while it's charging. The National Fire Chiefs Council (NFCC) recommends fitting smoke alarms in the room where you charge and store your ebike battery.
How to look after and store ebike batteries
How you look after and store your ebike battery will also affect its life expectancy. Follow these steps to increase its life:
- Avoid extremes of temperature where possible. Charge and store your battery at room temperature and away from direct sources of heat.
- Handle with care. Knocks, drops and vibrations could potentially damage the battery’s cells.
- Avoid long periods of storage if possible. If you do need to store your ebike battery for long periods without use, check what the manufacturer’s recommended discharged state is
- Be careful when washing your bike. Most modern ebikes, especially eMTBs, are designed to be ridden in wet weather. However, pressurised water from jet or pressure washers can penetrate the battery or electrics of ebikes and potentially cause serious water damage.
- Clean electrical connections regularly. Salt from gritted roads and pavements, or even soil, can cause corrosion, so make sure you clean your bike’s electrical contact points and battery mounting points frequently.
How long do ebike batteries last?
The life expectancy of lithium-ion batteries is often measured in charges, not years.
Shimano, for example, guarantees its STEPS-series batteries to hold at least 60 per cent of their maximum charge after 1,000 charges.
Bosch, on the other hand, guarantees its batteries will hold at least 60 per cent of their maximum charge after either 500 charges or two years of use, whichever happens first.
Giant’s electric bike batteries, which use Panasonic cells, are claimed to be good for up to 2,300 full charges. This also includes any combination of smaller charges that add up to 100 per cent.
Even when the battery’s capacity drops below the stated 60 per cent, it’s still usable. On average, quality Li-ion batteries should last for eight to nine years of use.
As a general rule, to maintain optimal battery health, a battery should be drained to below 10 per cent and recharged in one go at least once every three months to gain optional battery health.
Some brands have built-in hibernation functions on their charges. This puts the battery into sleep mode for long storage periods.
This is ideal for riders who may not use their over the colder months.
End of life and recycling ebike batteries
Modern electric bike batteries are more reliable and offer better longevity than ever. When the time comes to retire your battery, proper disposal is crucial and recycling is highly recommended to conserve the valuable minerals and materials used in the battery cells.
In fact, manufacturers have a responsibility when it comes to recycling ebike batteries. They are legally required to dispose of these batteries correctly and in line with regulations by ensuring authorised recycling facilities handle the batteries.
Some brands recommend that the battery be returned to a local retailer rather than to a local recycling centre, as the specialist company they use can recycle and reuse more batteries.
How dangerous are ebike batteries?
Modern lithium-ion batteries are deemed safe to charge at home. Very rarely, they can fail dangerously and pose a fire risk.
A voluntary testing standard called UL 2849 (which is endorsed by the likes of Trek, Canyon, Bosch and more) provides fire safety certification by examining the electrical drivetrain, battery and charger system combinations in ebikes.
Giant also complies with European testing standard 50604, which provides acceptable safety standards for voltage class A and B removable lithium-ion batteries.
Some ebike batteries carry a greater fire risk than others. The Bicycle Association says evidence confirms poorly regulated ebike conversion kits imported to the UK are “responsible for very many of the recent tragic battery fire incidents”.
Data on ebike-related fires is limited, but a Freedom of Information request by the Guardian found fires caused by ebikes and e-scooters had injured at least 190 people and killed eight by May 2023.
The London Fire Brigade says ebike and e-scooter fires killed three people and hurt around 60 in 2023 in the city.
Alongside the charging and storage guidelines already mentioned, the NFCC recommends regularly inspecting your battery for damage, which can cause sudden overheating.
All electric bike batteries sold in the EU will need to confirm to EN 50604 safety standards from August 2025.
This test ensures lithium-ion batteries used in electric bicycles (and other light electric vehicles) can withstand real-world conditions including crushing, immersion in water, exposure to sunlight and fire, and checking for thermal losses.
