18650 lithium battery pack assembly method
Several features to understand for 18650 lithium battery pack assembly:
- The 18650 lithium battery pack is assembled by welding multiple 18650 cells in series and parallel;
- The 18650 lithium battery pack needs a battery protection board to balance and protect every 18650 cells;
- The voltage error between each cell of the 18650 lithium battery pack should be within ten millivolts, and the smaller the capacity difference and internal resistance difference should be;
- The voltage of each cell of the 18650 lithium battery pack has two conventional voltages, one is the voltage of the traditional lithium-ion battery 3.7V, and the other is the lithium iron phosphate battery 3.2V;
- The cells used in the assembly of 18650 lithium battery packs must be of the same type and cannot be mixed with new and old cells, preferably cells produced in the same batch;
Therefore, the 18650 lithium battery pack assembly needs to prepare the following main things:
- Determine the voltage of the 18650 lithium battery pack that needs attention, and the capacity of ah;
- Prepare the corresponding number of 18650 lithium battery cells;
- Select a suitable lithium battery protection board;
- Welding equipment, cell holder, wire, battery shell, etc., and some other auxiliary materials;
Let's take a look at the analytic diagram of the 18650 lithium battery pack assembly structure:
As can be seen from the figure, the 18650 lithium battery pack is assembled by connecting the cylindrical 18650 lithium battery cells in series and parallel; after welding and fixing, after clicking the lithium battery protection board and installing the battery shell, An 18650 lithium battery pack is completed.
Let's talk about the reasons for several problems to be understood in the assembly of 18650 lithium battery packs:
- The reason for using the battery protection board, the lithium battery protection board is mainly an integrated circuit board that protects the rechargeable (generally referred to as the lithium battery). The lithium battery (rechargeable) needs protection determined by its characteristics. Since the material of the lithium battery itself specifies that it cannot be overcharged, over-discharged, overcurrent, short-circuited, and ultra-high temperature charged and discharged, the lithium battery component of the lithium battery will always appear with a protection board with a sampling resistor and a current fuse.
- The smaller the error of cell voltage, capacity, and internal resistance, the better. If the voltage error is significant, the cell with high voltage will be automatically charged to the cell with low voltage so that some cells in the battery pack are overcharged, and some cells are overcharged. The cells are "starved"; the internal resistance error is too large, resulting in unbalanced heating of the battery cells and unbalanced energization rate; The core is damaged by over-discharge; these factors will damage the efficiency of the 18650 lithium battery pack, and the service life will also decrease, and vice versa can improve the use efficiency and life;
- The 18650 lithium battery pack requires the same type of properties, and the old and new cells cannot be mixed. It is best to use the cells produced in the same batch, mainly because of the reasons mentioned in the above 2 points.
After passing the above knowledge points about the 18650 lithium battery pack assembly method, I believe everyone should have a good guide on how to DIY the 18650 lithium battery pack. As for other electronic components, such as battery protection boards, after knowing more, I believe that you can assemble 18650 lithium battery packs within a certain voltage and capacity by yourself.