Introduction to the assembly method of 18650 lithium battery pack

The assembly of 18650 lithium battery pack requires understanding of the following characteristics:
1. The 18650 lithium battery pack is assembled by welding multiple 18650 cells in series and parallel;
2. The 18650 lithium battery pack requires a battery protection board to balance and protect each 18650 battery cell;
3. The voltage error between each cell of the 18650 lithium battery pack should be within 10 millivolts, and the difference in capacity and internal resistance should also be smaller;
4. The voltage of each cell in the 18650 lithium battery pack has two conventional voltages: 3.7V for conventional lithium-ion batteries and 3.2V for lithium iron phosphate batteries;
5. The cells used in the assembly of 18650 lithium battery packs must be of the same type and properties, and new and old cells cannot be mixed together. It is best to produce cells from the same batch;
So before assembling the 18650 lithium battery pack, the following preparations need to be made:
1. Determine the voltage and capacity of the 18650 lithium battery pack that needs attention;
2. Prepare the corresponding number of 18650 lithium battery cells;
3. Select appropriate lithium battery protection boards;
4. Welding equipment, battery cell mounting brackets, wires, battery casings, and other auxiliary materials;
The assembly of 18650 lithium battery pack is achieved by connecting cylindrical 18650 lithium battery cells in series and parallel, welding and fixing them. After connecting the lithium battery protection plate and installing the battery casing, a 18650 lithium battery pack is simply completed.

Let's talk about the reasons for several issues that need to be understood in the assembly of 18650 lithium battery packs:
1. I believe many friends should know the reasons for using battery protection boards, so I won't go into detail here;
2. The smaller the voltage, capacity, and internal resistance errors of the battery cells, the better. If the voltage error is large, the high voltage cells will automatically charge the low voltage cells, resulting in some cells in the battery pack being overcharged while others are starving; Excessive internal resistance error leads to uneven heating of battery cells and uneven charging rate; The capacity error is too large, with some cells running out of battery while others are not, which can cause some cells to be over discharged and damaged; These factors can damage the efficiency and lifespan of 18650 lithium battery packs, and vice versa can improve their efficiency and lifespan;
3. In the assembly of 18650 lithium battery packs, it is required to use batteries of the same type and properties, and new and old batteries should not be mixed together. It is best to produce batteries from the same batch, mainly due to the reasons mentioned in the above two points.