16 - 32 Cell Balancer, BMS

Author	Message
analog8484 Senior Member Joined: 11/11/2021 Location: United States Posts: 198	Posted: 05:48pm 02 Mar 2026         Solar Mike said   The mosfets bolt onto 50mm wide busbars that extend off the LHS of the pcb, small solder lugs solder to the source pins for bolting to the "Source" busbar. The drain can use busbars bolted to top\bottom of the pcb, this presents extra current capacity and surface area for cooling; if max current is 40A in the sense mosfet, then 400 amps doesn't sound unreasonable for a current limitation. I have pulled apart a few 200A commercial BMS units that had self destructed, catching themselves and the interior battery case on fire, was not pretty.... they used 30 or more surface mounted mosfets in parallel groups connected by several 5mm round copper rods soldered to the pcb tracks; approx 40mm^2, 200A no way. Hopefully this design might be more robust and repairable. That's an interesting 400A design build approach.  Have you ever done it for that level of current before? I also have had issues with a couple 200A BMS units and find the designs marginal at best.  Look forward to seeing your 400A unit in action.