What Problems Should Be Paid Attention To When Assembling Lithium Battery Pack?

Lithium batteries must be assembled into lithium battery packs to meet actual application requirements. Matters needing attention in the cell composition of the battery pack: including cell screening, aluminum-plastic composite film, top sealing (edge sealing of the pole handle end), side sealing, protection of the pole handle, and measures to avoid mechanical impact and short circuit. 

1. The problem of battery screening, how to distinguish between good and bad after the battery is in hand. Must use internal resistance tester and capacity tester. Test the nominal MH, and the actual MH. If the distance from the nominal parameters is greater, the quality is worse. The lower the internal resistance of the battery, the better. The battery is a pit, check and test if you have equipment, and buy lottery tickets if you don’t have equipment

2. Aluminum-plastic composite film outer packaging protection: mainly to avoid being damaged by sharp parts. For this reason, the environment around the battery should be cleaned up from time to time, sharp parts are prohibited from contacting or hitting the battery cell, and gloves can be worn when taking it to avoid scratching the surface of the battery cell with fingernails.

3. Top sealing and side sealing protection: in order to avoid damage to the top sealing and side sealing and destroy the sealing effect, it is forbidden to bend the top sealing and the side sealing; at the same time, the cell design must adopt reliable insulation isolation Measures to avoid short-circuiting of the negative electrode and the aluminum-plastic composite film.

4. Pole handle protection: The positive lead terminal of the polymer lithium battery cell adopts an aluminum pole handle, and the negative lead terminal uses a nickel pole handle. Since the pole handle is thin, bending should be prohibited; at the same time, the pole handle and the aluminum-plastic composite film should be avoided in the production process, and the ferrule film should be strictly isolated.

5. Insulation protection: In order to prevent battery polarity short circuit when assembling multiple single cells in series, it is necessary to conduct insulation treatment. Use PC film or silicone film to separate the battery tabs and then wrap multiple layers of insulation. Tape to fix it, and then add an insulating layer to the position of the welding wire, and then add striped glue to fix it.

6. Avoid mechanical impacts, such as falling, hitting, bending the battery cell and accidentally trampling on the battery.

7. It is forbidden to short-circuit the positive and negative electrodes with metal objects or wires.

8. Waterproof protection: The lithium battery is assembled, and the whole is poured with insulating glue before packaging. Or choose a waterproof battery box.

9. The battery pack is required to be shockproof! Electric vehicles cannot be used as off-road vehicles in use! The outer skin of the battery pack can't be used to buffer the collision. Deformation will cause a short circuit! Try to use the grille bracket + cushion + outer box. Without the grille bracket, the battery pack will cause the nickel sheet to fall off under the squeeze of the battery pack for many years!

10. Do a good job of heat dissipation, and use a thermal conductive silicone grease pad as a medium to guide the heat to the stainless steel housing. Or the battery pack has conditions to provide a heat conduction channel, and during energy conversion, timely heat conduction can optimize the battery. Steel outer box + fan assist are conventional solutions.

11. Anti-corrosion problem. The battery will rust after being left for a long time. If possible, take anti-corrosion measures as much as possible.

Then. After a battery cell is completed, the next step is to correctly combine the casing and the battery cell protection circuit module to make it a polymer battery. The precautions in this process are as follows:

1). Shell design:

(1) Sufficient mechanical strength to avoid mechanical damage to the cell by external forces,

(2) When the battery core is installed in the shell, avoid the sharp edges and corners of the shell from scratching the battery core;

(3) Prevent short circuit caused by contact between the pure aluminum of the aluminum-plastic composite film and the outside.

2). The battery cell protection circuit must be designed: including the scientific setting of the maximum/minimum voltage, overcurrent protection, and the battery cell (single cell) must be protected against overcharge and overdischarge when used in combination.

3）. The transfer of the positive aluminum pole handle through the nickel strip and the connection between the battery cell and the circuit board should be implemented by ultrasonic welding or spot welding.

4）. Reliable positioning of the battery cell. After the battery cell is assembled, it should be fastened firmly in the housing without loosening at will, so that the entire lithium battery structure is in a consolidated state.

If the assembled lithium battery pack can be a reliable and safe application product, the above issues need to be paid attention to in strict accordance with the requirements. Otherwise, battery quality problems are prone to occur, ranging from scrapped and unusable batteries to natural or explosive accidents.