A set of 6 strings of 18650\150mah-3c battery pack (25.2V 4.5A), the cells are stored for more than 5 days, and the cells that have not lost voltage are sorted out for spot welding and protection board combination. Within 12 hours, one of the 6 cells in the battery pack dropped from the normal voltage to 0V, and the ratio reached more than 5 percent. After leaving the factory, customers will continue to find such battery packs.
Questions: 1. Before the batteries are grouped, the bad batteries that are sorted out can lose voltage at most 100mV (about one thousandth), and the batteries we use are within 10mv, why is it 12h after grouping? Can it drop from the normal voltage to 0V?
2. How should I proceed to analyze the battery cell or the protection board?
Hermione Posted on July 21, 2020
First determine whether the number of strings that will fall to 0V are all in the same string, personally think that the possibility of protecting the board is high.
Jody Posted on July 21, 2020
There is only one in series, a total of six.
Carlton Posted on July 21, 2020
There may be a problem inside the battery. The protection board is good or bad. Just try changing the battery pack.
Vince Posted on July 21, 2020
Will this happen without spot welding the protective board?
Jody Posted on July 21, 2020
No, I ordered hundreds of groups.
