Home » Questions » Does a passive BMS overly drain a lithium-ion battery when left idle?

Does a passive BMS overly drain a lithium-ion battery when left idle?

About a year and a half ago, I made an 11.1v battery pack with a 3.7v Li-ion battery in a 3s 7p configuration. After idle, the passive BMS seems to drain the battery. Can I try to restore the battery?

Battery Management System
September 21, 2023

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?

Jessica Liu

Jessica Liu is an engineer at MOKOEnergy with expertise in IoT devices, MCU, VCU, inverter, and BMS. She has a degree in automation, 6 years of work experience, and several certifications in project management.

Jessica Liu

What Others Are Asking

What key factors should be considered when designing an electric car BMS?

What key factors should I consider when designing an electric car BMS to ensure optimal performace and driver safety?

Jessica Liu January 22, 2024

How to test a BMS fault with a multimeter?

I want to test whether is my BMS fault or not and now I have a multimeter. Can you tell me how to test it with a multimeter? And please tell me what I should pay attention to during the testing process.

Jessica Liu January 22, 2024