On new or recent e-bikes you invariably get some kind of lithium-ion battery. Older second-hand e-bikes may have other chemistries; the earliest e-bikes featured very heavy lead-acid batteries, then came nickel-cadmium and nickel-metal hydride, both of which were lighter and can still be found to retain a useful amount of capacity for shorter runs.
However, despite the extra expense and complexity, a good quality, decent capacity lithium-ion battery is often the most practical option; it will give you the best range, reliability, and longevity. You might read all kinds of claims for different variations of lithium-ion e-bike battery, with cobalt, manganese, and more included in the mix. Don’t worry! There doesn’t seem to be any great expert agreement on which of these formulas is superior, so for now, it’s more important to get a well-made, high-quality lithium-ion battery, regardless of the chemistry used. In practice, this means batteries with cells (cells are the individual components of batteries) from reputable makers like Sony, Panasonic, and Samsung.
Electric Bike Batteries Types
- Lead-acid batteries
This is the oldest variant, which is used less and less every year. There are many reasons for this, the main reason being low capacity. Gel batteries weigh a lot, and the battery makes the construction of the bike very heavy. In addition, it charges slowly: it takes 8-10 hours to charge fully. This battery also has a short life, only 150-200 cycles.
- Nickel-cadmium (NiCd)
For many years, NiCd was the preferred battery choice for two-way radios, emergency medical equipment, professional video cameras and power tools. The standard NiCd remains one of the most rugged and forgiving batteries, and the airline industry stays true to this system, but it needs proper care to attain longevity. NiCd, and in part also NiMH, have a memory effect that causes a loss of capacity if not given a periodic full discharge cycle.
- Nickel-metal-hydride (NiMH)
NiMH has become one of the most readily available rechargeable batteries for consumer use. NiMH provides 40 percent higher specific energy than the standard NiCd. Nickel-metal-hydride is not without drawbacks. The battery is more delicate and trickier to charge than NiCd. With 20 percent self-discharge in the first 24 hours after charge and 10 percent per month thereafter, NiMH ranks among the highest in the class.
- Li-ion battery (Li-ion)
The most popular and optimal type of battery for an e-bike today. A lithium battery has the best combination of total weight and capacity. The specific capacity of lithium-ion batteries is the highest of all existing types and this is their main advantage. Lithium-ion batteries do not have the memory effect.
The disadvantages of this type include sensitivity to temperature conditions and an inability to charge quickly. The lithium-ion battery is also sensitive to overheating and requires control of the discharge mode. Aging and loss of capacity occur over time. The number of cycles is about 400, which is two and a half times more than the lead-acid battery.
Lithium-ion batteries for electric bicycles must be specifically designed due to the presence of a battery management system (BMS) within the pack. This piece of circuitry must be set appropriately to control the amount of current draw required by the motor and to limit excessive discharge capacity. The BMS is also important for balancing cell charges between the individual cells within the battery to maintain battery life over time.
- Li-Polymer
This type of battery is popular mainly among cell phone manufacturers because it’s incapable of operating an e-bike and does not withstand impacts and vibrations during the ride.
It is designed for use in electric cars where such vibrations are impossible. It is used very often in aircraft models where weight is important.
This is the most dangerous battery in terms of ignition! Under unfavorable circumstances (short circuits, failure of the BMS, accident) there is a high risk of ignition.
- LiFePo4
This is a relatively new but already popular type of battery. The advantages of this battery include frost resistance (it works in temperatures as low as -30 degrees Celsius without loss of capacity) and its ability to charge quickly. This type of battery has the largest number of full cycles, which is about 1,000. It is less susceptible to aging than the usual Li-ion. It is also devoid of the memory effect. The disadvantages of LiFePo4 batteries include low specific capacity and high cost.