What are the maintenance skills of lithium-ion batteries for electric vehicles

Disassembly and overhaul: Open the shell and take out the battery to check. The electric vehicle uses two battery packs. The voltage of each battery pack is 25V, and the two groups connected in series are 50V. Each group consists of 5 strings of X3 18650/2200mA batteries. After careful inspection, it was found that three batteries in a battery pack and one string were damaged, causing an open circuit and causing the battery pack to fail to charge. The 6 batteries in 2 strings in the other battery pack were severely damaged. After removing the bad battery and replacing it with a good one, connect each battery one by one. When replacing the battery, be sure to put a layer of insulating paper on the positive terminal of the battery (see Figure 1), and be wary of short-circuiting the positive and negative terminals during welding. [Note] When soldering the positive electrode, be sure not to take too long, otherwise it will easily cause overheating and damage to the battery. After welding, charge it with a small current for a period of time. After testing that each group of batteries is normal, then charge it with a normal current. There is a temperature sensor probe on the circuit board (see Figure 2), and it must be in close contact with the battery, otherwise it will not be able to protect it. The circuit board is designed with 5 sets of voltage monitoring points to monitor the voltage of each string of batteries, so that the charging voltage of each string of batteries reaches a balance. After the overflow, the total voltage is measured. Each battery has only 20V, which cannot reach the original design index and can only be used properly. [Hint] The reason for the damage to this group of batteries may be caused by overcharge and discharge. In principle, lithium batteries should be charged as they are used. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous article: BYD lithium iron phosphate battery management system BMS function