BMS balance circuit LEDs?

[Hot Toddy]

I’m testing a 13S5P 18650 li-ion pack I’ve built to confirm the balance charge function. I’ve removed the backing fish paper from the BMS board to expose the balance circuitry In order to (hopefully) monitor the balancing of each cell group as they reach their cut-off voltage of 4.25v before discharging through their balance resistor back to a (balanced) 4.2v. I’m using CC/ CV bench power supply set at 3A and 55v. Charging went as expected, BMS disconnected the charger around 55v, but no LEDs lit on the BMS to indicate balancing was happening. Then it hit me! Are there actually LEDs built into the BMS balance circuitry? The examples I’ve seen on YouTube suggest they do. But nothing lights on my BMS (standard clone from China). Do standard BMS’s contain LEDs for monitoring balancing? Or was I expecting too much?

Thanks

 

[jonyjoe303]

I never seen balance LED's on any BMS I use, and I used at least 10 different ones li-ion and lifepo4. Some of the small balance boards and active balancers do have LED's but thats an entirely different component.

 

[JackFlorey]

no LEDs lit on the BMS to indicate balancing was happening.

Most balancers do not have LED's. They use resistors to dissipate excess power from cells that are reaching their target voltage.

 

[Hot Toddy]

Thanks for the replies. Makes perfect sense as the BMS is typically built into the pack and never seen again. So no point adding the manufacturing cost to add them.