4PCS 4S 30A 12.8V 18650 Lithium Iron Phosphate Battery Protection Board LiFePO4 4S 30A BMS Balancing Charging Circuit PCB Board

thank you and thank you for the cheap beeing

This BMS board does not work at all with my 4S LiFePO4 battery pack. The BMS circuit is supposed to disconnect the charging voltage when the voltage reaches the maximum value that can be applied to any cell in the battery pack. For a 4S LiFePO4 battery, the max voltage should not exceed about 14.4V. I expected the voltage on the battery terminal to stop increasing when the charging voltage reached that value. However the BMS did not shut off the charging voltage, but continued to rise. Luckily I limited the max charging voltage to 15V so the battery cells survived the small amount of overvoltage, especially since I was able to disconnect the charger quickly after observing the BMS fault. I tested a second board of the 4 included, but it has the same problem. Do not buy. There’s a danger this BMS will cause irreparable damage to your battery pack.

Dunno what's wrong with these things but they don't really work. Can't even drive a drill motor with no load.

You can clearly see that this diagram is incorrect. It shows the positive and negative leads go to the wrong pad on the pcb. I burned out a couple of usb chargers because of this

Straight up junk! Don't waste your money, should report to Amazon for faulty boards