On this blog I deal with the issue of electric bicycles, which is why I will be referring to them. The battery can be tested directly in the bike with proper precautions and frequent voltage control with a meter. During charging, we check the voltage of each section on the BMS plug and make sure that none of them overcharges above 4.25V. Finally, BMS must disconnect the charger when one of the sections reaches a dangerously high level of charge
Next, while driving, every few kilometers we stop and check the voltage on each section and when we reach the level of approx. 3.3V / section, we compact the measurement frequency to check if BMS cuts off the power in the area of 3V / section.
You can also try to remove one of the wires from the BMS plug. This simulates a sudden drop in voltage on the battery section and at this time the voltage should not go to the motor controller.
Most BMSs have thermal protection, which should be attached directly to the battery cell. If this is not the case, we can add our own thermostatic fuse and plug it into, for example, the controller’s e-lock or brake circuit. After exceeding the maximum temperature, the fuse will cut off the controller power supply, and thus the current consumption from the cells, and thus prevent further heating by discharging.