How to choose Electric bike batteries

Common e-bike Battery Types

Lithium batteries are light and efficient

When buying an ebike today,there are only two types of battery chemistry you are likely to encounter. Lead acid, which is the older, heavier, dirtier and cheaper option; and lithium ion, which is the newer, lighter, far longer lasting and efficient, and more expensive option. The vast majority of new electric bicycles are equipped with lithium ion batteries, and I would suggest staying away from lead acid chemistry unless you absolutely need to save a bit of money. Lead acid batteries typically fail after 100 to 300 charges, and during this time their max capacity falls very quickly.

Lithium ion cells last far longer on the other hand, usually lasting to between 700 to over 1000 charges before dropping below 50% capacity. They have next to no “memory effect”, meaning that you can partially charge them without issue and their natural discharge over time doesn’t create the problems which are experienced with older chemistry types such as lead acid. They are extremely light in comparison to other batteries which is ideal for electric bikes, and they also carry a large charge so you can travel further on a single charge. The biggest drawback with the technology is that it is expensive and is likely the most costly component of any ebike.

Electric Bike Battery Capacity

When choosing your electric bike battery or browsing the battery capacity on an ebike you’re thinking of purchasing, there are generally two figures provided which describe the capacity; Voltage (V), and Amp hours (Ah). Both of these contribute to the overall capacity of the battery, so higher voltage or a greater number of amp hours, translates to larger capacity and a greater distance you can travel on a single charge. In fact the best way for you to get a “feel” for the capacity of a battery is to multiply the two numbers together which will give you the Watt hours (Wh). For example:

Battery A: 24V * 10Ah = 240Wh

Battery B: 36V * 8Ah = 288Wh

So Battery B has a total of 288 watt hours, providing it with a larger capacity that will take you further on a single charge than Battery A. It’s impossible to exactly say what distance a battery’s full charge will actually cover, there’s too many variables such as hill conditions, amount of pedaling, outside temperature, total weight, wind etc. As a very rough guide, a 36V 10Ah battery powering a 250W motor and ridden under standard conditions will cover 50-60km. That includes light pedaling and few hills. In tough and hilly conditions that distance can easily half.

Ebike battery capacity is not the only important aspect, it’s also worth paying attention to voltage options.

Sticking with our no-nonsense explanation, voltage can be thought of as the ability for the battery to provide energy over the shortest period of time possible. Basically, it affects the max power which the battery is capable of providing. Batteries and motors work their hardest during hill climbs, and an electric bike with a 24V battery may not climb as fast or as well as an identical electric bike with a 36V battery. What is crucial here is to match the battery to the motor. A powerful electric motor will require a relatively higher voltage battery to perform at its best, while on the flip side a weak electric motor with a high voltage, high capacity battery, is not getting any performance advantage from the higher voltage (although the capacity is obviously better).