I’ve used a 4S 5P LifePO4 battery (500Ah, 12V) for three years and it worked well. Recently I accidentally shorted two cables, for a second only, and the BMS stopped charging, although it still discharges fine. The BMS (Donguan Weimei) has no resettability and I shorted B- and P- to check if it does maybe reset, it did not. I concluded that it fried the BMS partially. I checked by discharging and charging bypassing the BMS, and the cells worked perfectly without BMS. Voltage on each individual cell is exactly the same at 3.296V. I ordered a Daly 12V 100A BMS which arrived today. After connecting up, the charging current is only 10A and should be 50A max (my Victron charger can deliver 40A).
There is no discharge current. Voltage over battery starts at 3.5V with BMS installed and gradually drops to 2.5V. All connections checked and rechecked. Voltage over the bank not including BMS is 13.19V.
Soooooo… was I unlucky and got a faulty Daly BMS, or could something else have gone wrong? All connectors are checked for continuity and all diagnostics over cells check out perfectly, but no current coming through BMS when trying to draw current.