The ebike battery is a crucial part of any electric bike, determining the motor performance, power output and range.
The battery will also have an impact on your bike's overall weight and therefore its handling.
In this article, we’ll take a look at the different types of ebike batteries and how to care for them, as well as exploring 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, with each offering 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 750Wh capacity.
Lightweight ebikes, with battery capacities ranging from 250 to 320Wh, 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 200Wh 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 will be able to 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 more capacity.
For riding an ebike off-road, racking up elevation on soft ground with grippy mountain bike tyres, a higher-capacity system (625-750 Wh) 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 and weather all impact the range of an ebike battery.
Bosch has a handy online tool that gives you an idea of the range you will achieve from its various ebike motors and batteries.
The calculator combines information about the rider, bike and tour (as well as average speed and assistance mode) to generate a range estimate.
According to Bosch, a rider with a total weight (body, bike and luggage) of 100kg, riding a Bosch CX Performance Line-equipped eMTB with a PowerTube 625Wh battery would achieve a 36km range at 18 km/h in eMTB assistance mode through mountainous terrain.
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 maximise 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 will 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. Bosch, for example, recommends a charge level of 30-60 per cent for long-term storage.
- 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.
However, 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.
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.
Silverfish UK (which distributes electric bikes such as the Yeti 160E), has the following note on its website:
“We are obliged to take back, free of charge, waste industrial batteries supplied to an end user for proper treatment and recycling. Silverfish will, therefore, take back and recycle free of charge eBike batteries supplied by us…”
If your ebike battery has reached the end of its life, the first port of call should be your manufacturer or local distributor, who will be able to inform you on the takeback and recycling procedures available in your country.
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.
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.
