Bms discharged completely parallel cell

sahbin

10 µW
Joined
May 7, 2015
Messages
5
Location
Brussels
I am currently building an ebike and I was nearly done but I had to put the project on hold for about a month.

When I returned on the project, the last cell parallel pack of my battery was completely drained ( I have a 20s8p battery pack). I made the battery pack from new cells and they were all balanced when I last worked on the bike.

I have an Ant BMS and I read that sometimes a balancing shunt resistor could be stucked and cause one parallel pack to be drained. Did someone deal with this kind of problem ?
Does someone know how to repair that "stucked" shunt resistor (probably a transistor issue?).

Thanks
 
It is not uncommon for many models of BMS to blow a shunt transistor. These are incredibly small, surface mounted things. Unless you have the skill and equipment, replacing it is very difficult. I would recommend replacing the entire BMS unit. You might be able to get one under warranty if you ask the seller.

The most common cause of blown shunts is improper hookup sequence when attaching to the pack. Always connect the B- first, then the balance tap wires, and B+ last.
 
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