Electric Bike Batteries: Everythink You Need to Know

An ebike battery powers the motor, propelling you forward via the throttle or pedal assist. Replacing the cheaper but heavier and less durable lead-acid batteries are lithium-ion batteries. They comprise individual battery cells – plus wiring, connectors, charge level indicator lights, and a battery management system (BMS) – to form a battery pack stored in a protective shell.

Your choice of motor and battery can influence things like performance, travel range, weight distribution, and battery lifespan. How you ride matters, too. By understanding what goes into the battery of an ebike, you can choose one that fits your needs and budget.

What is a Battery Pack?

An ebike battery pack consists of individual lithium-ion cells – around 20 to 50, depending on lithium content and battery capacity – connected through wires and stored in a battery casing.

Each cell is a cylinder shape, measuring 18-20mm in diameter and 65-70mm long. A higher cell count equals a higher voltage rating, meaning the battery can store and transfer more electrical current to the motor.

What is the Most Common Type of ebike Battery?

Lead-acid batteries were once common cheaper electric bikes due to being inexpensive to produce. However, lead-acid batteries are notoriously bulky, hard to maintain, prone to rapid deterioration, and recognized as a fire hazard to the hydrogen gas they release while charging which can lead to an explosion.

Today, most ebikes run on lithium-ion batteries as they are safer, can hold more power, charge faster, and last longer with minimal care. They are also small enough to store in a battery case and placed onto an ebike in various configurations, such as mounted onto or directly integrated into the frame.

Electric Bike Battery Terms and Definitions

Do you need to be an expert to choose the best ebike battery? Well, no. But your understanding of watts, volts, and amps can help you choose a battery with optimal range without sacrificing comfort and performance. Here are the terms and definitions to be aware of.

Watts (W)

Watts is the amount of power produced by an electric motor. The average watts range for a long range electric bike is between 250 and 1000w but some can go higher. Ebike manufacturers typically list two watts metrics: continuous and peak, where the former is the maximum output that the motor can sustain over a long period, and the latter is the maximum output for a short burst.

As an example, the Heybike Mars 2.0 has a 750w brushless geared hub motor with a peak output of 1400w. This means the motor can produce 1400w of power for a short duration in ideal applications, such as accelerating from zero on a flat, smooth surface while carrying a heavy load in a large basket.

Watt Hours (Wh)

Watt hours is the estimated watts a battery can convert into usable energy for a motor per hour. This metric is one of the most accurate ways to determine a battery’s potential range. It also refers to continuous power, so you can estimate that a 500wh battery will deliver about 500w for one hour.
This table shows how different Wh and load combinations can produce different run times.

Keep in mind that many factors influence battery range and lifespan – even how you store your electric bike during winter.

Voltage (V)

Voltage, or volts, determines the force of the electrical flow from the battery to the motor or the speed at which electrical current travels through a system. A higher-voltage battery can provide more power to the motor, resulting in faster acceleration and an extended travel range so you can ride longer distances on a single charge.

The average voltage range for an ebike battery is 36-48V or higher.

Amperes (Amps)

If voltage is the speed of electrical current, amps is the volume of electrical current drawn from the battery at a given time. To explain this clearly, let’s use the traffic analogy, where more amps equal more traffic lanes and more volts equal faster cars. Hence, a higher amp count means the motor can produce more power.

Amp-Hours (Ah)

Ebike manufacturers typically don’t list the amp count for their products. Instead, they list amp-hours, which is how many amps the battery can deliver in an hour. For example, a 14.4Ah battery can produce about 14 watts per hour. That said, this info alone cannot estimate travel range, as you need to use it as part of your calculation to determine watt-hours.

Seeing as watt-hours is a combination of voltage and amp-hours, a typical calculation looks like this:

48V x 14.4Ah = 692Wh

Based on the above calculation, this battery would produce about 692 watts per hour.

Battery Management System (BMS)

The Battery Management System is a crucial component of the lithium-ion battery pack. Inside, the Battery Protection Circuit Board (PCB) controls the charging and discharging of the battery cells and ensures the temperature and electrical flow are within safe limits.

Combined with other safety features (temperature, short circuit, and over-current protection), the BMS prevents over-charging and overheating to maximize the battery’s lifespan.

Why Does This All Matter?

By increasing your understanding of e-bike battery capacity, you will have an easier time choosing one that complements your motor and desired travel range. You will also avoid the “bigger is better” mentality trap, where you opt for a larger-than-needed battery only for the weight increase to be a detriment to your ride quality and comfort.

How Long Does an Ebike Battery Last?

One of the most common questions we get from riders is: How long does an ebike battery last?

The average lifespan of an ebike battery varies based on battery quality, usage, and care. As a rough estimate, you should get at least 3 to 5 years (or 500 to 1,000 charging cycles, where each cycle represents a full charge from 0 to 100%, or two charges from 50 to 100%) from your battery – before the total capacity starts to drop.

After reaching the rated number of charging cycles, your battery will drop to 80 or 60% capacity until it fails.

What is UL 2849 Certification?

UL 2849 is the Standard for Electrical Systems for ebikes. This certification confirms that all electrical components on an ebike, including the electrical drivetrain and battery and charger system, meet the highest international standards in electrical safety and fire safety.

All Heybike batteries meet the UL 2849 standard confirmed by TUV Rheinland in the US and Canada, meeting the highest quality and safety standards.

Last Thoughts on Ebike Batteries

Trying to calculate your ebike travel range can be a challenge. If you’re unsure what battery and motor combo is right for you, talk to a professional dealer. They can assess your riding needs and budget and recommend the best model for you. Alternatively, you can contact your preferred e-bike manufacturer for advice. Every bit of extra knowledge will help you make an informed purchase.