Guru
Joined: 08/02/2015
Location: New ZealandPosts: 1204
| Posted: 09:38pm 23 Feb 2026 |
Software written for the BMS, have it working on a Master and 2 slaves, need to go and get a sheet of 2mm thick aluminum and assemble all 16 slaves + 0.36R load resistors, so I can test out on a small 180AH 16 cell battery currently putting together.
For the 300A SSR relay, have scrapped the idea of measuring the load current across the busbars as the loads are not even along the length due to the mosfet connections. Could measure the voltage drop across all paralleled mosfets, combined 0.15 mR, but this changes with temperature and isn't consistent.
Instead have opted to use an isolated current sense ACS723,40U in the source of the last mosfet, as all mosfets are tightly thermally connected by being bolted to an alloy bar 50 x 3 mm, they will all tend to current share; so whatever current is flowing in the sense mosfet will be proportional to their combined total. This will allow a max of 400 amps to be sensed with little extra heat.
Here is a conceptual schematic:
Cheers
Mike