16 - 32 Cell Balancer, BMS

Author	Message
Solar Mike Guru Joined: 08/02/2015 Location: New Zealand Posts: 1204	Posted: 01:15am 17 Jan 2026         Godoh said   Wow Mike that is a lot of work! Pete I guess, prob about 24 hrs to do those pcbs, so not too much, and now that I have retired, I don't get paid for it.... I have been using a different sort of balancer for our 3 banks of 300AH 48v Lead Carbon 6v cells, so 8 cells in series per bank; will post the pcb below. That system uses a flying 1uf capacitor that gets switched across each cell in the bank via DPST optomos relays, type AT224, the cap is then isolated from the bank and switched to an ADC input of the CPU, measured, then discharged, cycle repeats for next cell. Any balance loads that maybe on at the time are switched off during the voltage measurement phase to prevent voltage drops on the balance wires. Takes about 1 sec to scan all 8 cells in the battery; system works pretty well but would be a bit slow if expanded to 16 or 32 cell Lifepo4 banks, thus the new design. The cell loads are power resistors screwed to a large heatsink, mosfet switches driven by an opto to voltage isolator chip TLP3906. The new design will be much faster and cheaper to build, as the cpu's are about $2 each and other opto components not required. Here is the older balancer PCB, as its serial driven, extra boards can be daisy chained for more cells as required: And it's controller: Cheers Mike