Electric bicycles provide an efficient and convenient mode of transportation, especially for short to medium distances. They allow riders to cover longer distances with less effort compared to traditional bicycles, making them suitable for commuting and running errands.

The popularity of e-bikes continues to grow globally as more people recognize their advantages in terms of sustainability, health benefits and ease of urban transportation.

Which battery is best for electric bikes?

Lithium-ion batteries are considered the best battery types for your electric bike. This is because they require less maintenance and also pack in a lot of energy-densities required to power this machine. They are also light and therefore suitable for the sizes of electric bikes.

So can we make our own lithium battery packs for electric bikes?

Electric bikes batteries are mostly made out of lithium-ion batteries and one of the most common type used in these bicycles are 18650 cells. One would thing that making a battery pack for such an invention as the electric bike is an industrial responsibility alone. People normally associate such practices with large manufacturing plants and think that a DIY process is impossible.

In the real sense, making such a battery pack requires a few simple steps to be followed in their correct order and can be done at home.

But before you start DIY you need to be clear about the notes：

1, first of all, you need to be clear about your electric bicycle voltage, capacity, the power of the motor, such as voltage 48V, capacity 20AH.
The nominal voltage of electric bicycle, the conventional is: 36V, 48V, 52V, 60V, 72V, need to pay attention to the power of the motor, is to choose the right electric core. If you choose improperly, the instantaneous power of the motor is larger than the output of the core, or exceed the upper limit of the protection plate protection, it will directly burn the BMS.

2, determine the charger and charging port
Charger is not universal, voltage mismatch or too much current, will directly burn the battery or make BMS damage.
Charging port is also to be noted, you can choose according to the original charging port.

3、Determine the space of the battery pack
Battery pack if the size is made too large and does not match the location of the installed battery pack, it will lead to the whole battery pack can not be used.

Materials required:

1. Lithium-ion battery cells

2.Battery Management System (BMS) for safe and efficient operation.

3.Battery connectors and wiring harness for secure connections.

4.Insulating materials such as heat-shrink tubing or insulating tape.

5.Thermal management components like heat sinks, cooling fans, or other cooling mechanisms.

6.Mounting brackets or holders for secure attachment to the electric bicycle frame.

7.High-quality wiring and connectors for reliable connections.

8.Testing equipment to verify voltage, capacity, and functionality.

9.Packaging materials for transportation and storage.

10.Labeling materials for identifying voltage, capacity, and manufacturer details.

For example:

If a 48V 20AH battery pack, we would require lithium-ion cells with a total capacity of 20,000 milliampere-hours (mAh). Depending on the specific cell chosen, this could involve a combination of individual cells with capacities ranging from 2000mAh to 5000mAh.

Manufacturing and assembly process:

Design the battery pack layout: Determine the layout and configuration of the battery cells based on the available space and desired dimensions of the battery pack. In this case, for a 48V 20AH battery pack, you would need a combination of series and parallel connections to achieve the desired voltage and capacity.

Prepare the battery enclosure: Select or design a suitable battery enclosure or case that can accommodate the chosen number of battery cells. Ensure that it provides adequate protection, insulation, and ventilation for the battery pack.

Install the Battery Management System (BMS): The BMS is a critical component that ensures the safe and efficient operation of the battery pack. Install the BMS inside the battery enclosure, following the manufacturer’s instructions and wiring diagrams.

Connect the battery cells: Connect the lithium-ion cells in both series and parallel configurations to achieve the desired voltage and capacity.

For example, if using 2900mAh cells, you would require approximately 7 cells in parallel (20,000mAh / 2900mAh ≈ 6.8965, approximately 7 cells).

For series, you would need a series configuration of 13 battery cells (3.7V per cell) to achieve a total voltage of 48V(48/3.7≈13).

Use appropriate battery connectors and wiring harness to establish secure connections between the cells.

Insulate the battery connections: Apply insulating materials such as heat-shrink tubing or insulating tape to cover and secure the battery connections. This prevents short circuits and provides electrical insulation.

Thermal management: Consider incorporating thermal management components to regulate the temperature of the battery pack during operation. This may include heat sinks, cooling fans, or other cooling mechanisms, depending on the specific design requirements.

Mounting brackets or holders: Install mounting brackets or holders inside the battery enclosure, if necessary, to securely attach the battery pack to the electric bicycle frame. Ensure proper alignment and fastening to maintain stability during usage.

Wiring harness: Connect the output terminals of the battery pack to the appropriate connectors or wiring harness that will interface with the electric bicycle’s controller. Use high-quality wiring and connectors for reliable and low-resistance connections.

Testing and quality control: Thoroughly test the battery pack using appropriate equipment to verify its voltage, capacity, and functionality. This step is crucial for ensuring a safe and reliable battery pack. Perform quality control checks to identify and rectify any issues before finalizing the assembly.

Close and seal the battery enclosure: Once all testing and quality control checks have been completed, securely close and seal the battery enclosure to protect the battery pack from external elements like moisture and dust. Ensure proper sealing to maintain the integrity of the enclosure.

Labeling and packaging: Clearly label the battery pack with relevant information such as voltage (48V), capacity (20AH), and manufacturer details for identification and safety purposes. Package the battery pack appropriately for transportation and storage, adhering to any regulations or guidelines specific to battery shipping.