Electric bike battery: everything you need to know in 10 key points

The battery is at the heart of an electric bike's (EAB) energy supply. It directly determines its performance, range, handling, and comfort of use. Whether you're a casual cyclist or a daily user, understanding the characteristics of an electric bike battery is essential to making an informed choice that's suited to your needs. Voltage, capacity, energy, range, power, technology, weight, charging time, and even location: here's an overview of the many criteria to consider in 10 key points.

1. The voltage of an electric bicycle battery

Expressed in volts (V), voltage is the strength with which a battery's electrical current is delivered. The higher the voltage, the more power the battery will provide to the motor with less current.

For an electric bike, a voltage of 24V corresponds more to older batteries, intended for light use. The 36V electric bike battery currently equips the majority of electric bikes, with a standard voltage.

A battery with a voltage equivalent to 48V can also be chosen for higher power and torque for the electric bike motor : this is the case with the Cyclee Valeo battery that equips our Le Formidable electric cargo bike. Finally, a voltage of 52V will be more suitable for electric mountain bikes, speed bikes or electric-assisted bicycles designed for high performance.

2. Capacity

The capacity of an electric bike battery, indicated in ampere-hours (Ah), corresponds to the amount of electricity that can be stored and delivered. For example, a 10 Ah battery can deliver 1 amp for 10 hours or 5 amps for 2 hours. Like a tank, the higher the battery capacity, the longer it will allow the bike to ride without having to recharge. However, the recharge time to be expected will be longer with increased capacity, knowing that the average charging time for an electric bike battery is between 3 and 6 hours.

3. Energy

Often confused with capacity, energy is one of the most important data of an electric bike battery. Indeed, it is this which allows us to estimate the autonomy. It is measured in watt-hours (Wh): the higher the number of watt-hours, the longer the battery will be able to power the motor. It is obtained by the following calculation: voltage (V) x capacity (Ah) = energy (Wh); for example: 36V x 14 Ah = 504 Wh. On average, an electric bike consumes approximately 10 to 15 Wh per kilometer.

For information, the battery of the Galian Le Formidable electric cargo bike has an energy of 630 Wh.

4. Autonomy

The energy in Wh indicates the theoretical autonomy of the e-bike battery. Thus, the 630 Wh of the Formidable battery gives it a theoretical autonomy of up to 80 km.

However, several additional factors will determine the consumption and therefore the real autonomy of an electric bicycle battery: the level of assistance chosen (eco, standard, cargo or turbo for example), the type of bicycle (a mountain bike consumes more than a city bike), the weight of the cyclist and the bicycle, the difference in altitude and the type of terrain (flat, uneven, hilly, mountainous, etc.), the weather (presence or absence of headwind) and the temperature (the cold in particular reduces the autonomy), but also general maintenance with tire pressure, the condition of the brakes and the motor among others.

In any case, your battery life can be constantly monitored thanks to a specific command displayed on the LED console or LCD screen of your electric bike.

5. The power of an electric bike battery

For a suitable electric bike battery, it is important to ensure its power, that is, the intersection between the energy (Wh) it can store and deliver on the one hand, and on the other hand, the power (W) that the electric bike motor can use. Most e-bikes have a 250W motor which corresponds to the legal limit, but for more powerful motors (for a fat bike for example), a battery delivering more current will be necessary. Finally, it is necessary to take into account the discharge current (A), that is, the capacity of the battery to supply current without damaging itself: this is the instantaneous power that the battery will deliver.

6. Technology

Chemical technology can vary from one e-bike battery to another: let's discover their advantages and disadvantages.

The lithium-ion (Li-ion) battery is the most common today. It has good energy density and a long lifespan while being lightweight. Furthermore, it does not have a memory effect, i.e., the reduction of its usable capacity to the level to which it has been regularly discharged before. However, it remains more expensive than other technologies.

Also having a long lifespan, the lithium iron phosphate (LifePO4) battery presents a minimal risk of overheating, despite being heavier and bulkier.

The advantage of a lithium polymer (Li-Po) battery lies in its compact and flexible volume, however this model will be less stable and will require good charge control.

As for nickel metal hydride (Ni-Mh) batteries, they are now less used due to their disadvantages: heavier and obsolete more quickly, they have a significant memory effect.

Lead-acid batteries, on the other hand, are very heavy, have a short range and lifespan despite their low price. They are therefore hardly ever used on electric bikes anymore, except for some entry-level ones.

7. Weight

The weight of a battery is a significant factor, accounting for 15 to 25% of the total weight of an electric bike. It can affect its range, performance, and handling.

Generally between 2 and 4 kg, the weight of an electric bike battery depends on:

• Battery capacity: the higher it is, the heavier the battery.
• Technology: a Li-ion battery has a good weight/energy ratio, unlike others (Ni-Mh, lead), which are heavier and less used.
• The format: the weight of a battery integrated into the frame will be better distributed, but sometimes more substantial, while a removable format will be more compact, but will limit the autonomy.

8. Location

On an electric bike, the location of the battery can differ depending on the use of the e-bike, its design but also the desired center of gravity.

It can be located on the rear rack, especially on city bikes and cargo bikes with a motor located in the wheel, which makes it easier to access for removing and loading. However, the center of gravity will be higher and therefore potentially hinder balance due to the weight. This location can also be less aesthetic and make it more difficult to install a baby bike seat on the rack.

Integrated into or on the frame, the electric bike battery ensures better weight distribution and increased stability thanks to its low center of gravity. This positioning can also be more aesthetically pleasing.

For some cargo bikes, particularly two-wheelers and three-wheelers, the battery can be placed under the passenger seat in the front box. While this is discreet and space-saving, removing it can sometimes be complicated.

Finally, for folding bikes, the battery can also be attached in or on the seat tube to offer a compact solution, although this can reduce its capacity due to the reduced space available, or sometimes hinder getting on or off the bike.

Regardless of the model and location, the battery of your electric bike is in principle always removable - with the exception of batteries integrated into the frame - to allow it to be recharged at home, at the office or in a place that does not allow the charger to be directly connected between a power outlet and the battery attached to the bike.

💡 Tip: some brands, like Galian, offer an additional battery upon purchase to avoid being caught short when setting off, to avoid being dependent on recharging time or to maximize the autonomy on your journey!

9. Charging time of the electric bike battery

Charging time varies according to several criteria:

• Battery capacity, as we saw earlier: the larger the capacity, the longer the charging time. For example, the Ultra e360 Cyclee Valeo battery in Galian's Formidable can be recharged in 5 hours and 20 minutes. 
• The power of the charger: the higher the power (4 or 6 Amps instead of 2A for example), the faster the charging.
• Ambient temperature: Very cold or very hot weather can slow down the battery charge or cause it to protect itself.
• Discharge level: logically, recharging a battery whose level is at 0% will take longer than if it is partially discharged at 40%.

👍 Good to know: some chargers have the advantage of stopping when the battery is fully charged.

To ensure proper battery use, it is important to follow the instructions provided with the battery and only use the official charger recommended by the manufacturer. For safety reasons, it is best to avoid charging at night and prefer a garage or closed room rather than a connection inside your home.

10. Lifespan

Under normal use, a battery has a lifespan of 4 to 7 years. This equates to approximately 50,000 km, or approximately 500 to 1,000 complete charge cycles, with one cycle consisting of a total discharge followed by a 100% recharge. After 500 cycles, the battery gradually loses its autonomy, providing only 70 to 80% of its initial capacity.

To optimize its lifespan, here are some tips you can follow:

• Choose a reputable brand (e.g. Bosch, Shimano, Yamaha, Panasonic, Valeo) that uses higher quality, longer lasting battery cells.
• Store your battery between 10°C and 20°C, away from humidity and avoid exposing it to extreme cold or intense heat: in winter, bring it inside and in summer, refrain from parking the bike in the sun.
• Clean the battery contacts regularly.
• Some batteries can be reconditioned by replacing the cells, but it depends on the model and cost.

So, you're now able to choose the right electric bike battery or make sure the one you have is right for your bike. By considering the technical specifications (voltage, capacity, energy), technology, and even the location and weight of your battery, you can optimize your bike's range and performance. With proper maintenance, your electric bike battery can last for several years and accompany you peacefully for thousands of kilometers. It's your turn to recharge the batteries!

▶️ Also read: Which battery should you choose for your electric bike? Our practical guide.