Yes, when idle, the Passive BMS can drain the lithium-ion battery.
- A passive BMS is powered by a battery, and a good BMS draws on the order of 1 to 10 μA from the battery cell.
- A poorly designed BMS may draw 1-10 mA, which is sure to overdischarge the lithium-ion battery in a relatively short period of time.
Furthermore, recovering the battery becomes challenging if its voltage drops below 2.5 volts. If the battery is fine, a new BMS can help.
MORE: Will BMS shut down when BMS SOC is high?