An e-bike battery is the core power source of an electric bicycle.
Many buyers think the battery is just a “black box,” but in fact, it is made up of several key components.
Each component plays an important role in safety, performance, lifespan, and overall reliability.

Here is a complete breakdown of what an e-bike lithium battery is made of:

1. Battery Cells – The Heart of the Battery

The cells are the most important and expensive part of the battery pack.
They determine capacity, lifespan, power output, and safety.

Common cell types:

• 18650

• 21700

• 32700

• Pouch cells

Common brands:

• Samsung, LG, Panasonic, CATL, EVE, Lishen

Key performance factors decided by cells:

• Capacity (Ah)

• Cycle life

• Thermal stability and safety

2. BMS (Battery Management System) – The Brain

The BMS is the “brain” of the battery pack.

Its functions include:

• Overcharge protection

• Over-discharge protection

• Overcurrent protection

• Short-circuit protection

• Cell balancing

• Temperature monitoring

A battery without a BMS is unsafe and can easily become damaged or hazardous.

3. Battery Case / Housing

The outer case protects the internal battery structure from impact, water, dust, and vibration.

Common e-bike battery cases:

• Hailong battery case

• Silverfish battery case

• Rear rack battery case

• Tube-style battery case

The housing provides:

• Waterproof and dustproof protection

• Impact resistance

• Secure installation on the bicycle

4. Nickel Strips & Internal Connection Structure

Cells are connected in series and parallel using nickel strips.

Their functions:

• Conduct current

• Build battery configurations (e.g., 10S4P, 13S4P, 14S5P)

• Maintain low internal resistance

High-quality nickel strips provide better current flow and lower heat generation.

5. Charging Port & Discharge Connector

These ports allow the battery to connect to the charger and the e-bike’s controller.

Common charging ports:

• DC 2.1 / 2.5

• XLR

• Aviation plug

Common discharge connectors:

• XT60 / XT90

• Anderson plug

• Bullet connectors

Port selection affects:

• Compatibility with your e-bike

• Maximum safe current output

6. Insulation & Padding Materials

To protect the internal cells, batteries are filled with:

• Fire-resistant foam

• Insulation sheets

• PVC wrapping

These materials prevent:

• Vibration damage

• Internal short circuits

• Thermal risks

Summary: An E-Bike Battery Is Made of 6 Core Components