Guru
Joined: 08/02/2015
Location: New ZealandPosts: 1204
| Posted: 02:50am 15 Feb 2026 |
Have started building up the pcbs for the balancer, have the controller and a couple of the cell monitor slaves built; will test out and write some software to make sure all is working, then make the remaining 14 slave modules.
What I really need is a SSR relay, with an inbuilt current shut-down, this can be connected to the BMS Load output and act as a main Load relay to the inverter supply input, combined with a simple resistive pre-charge function. The over current setting would have a pot to set between low and high limits for various testing purposes.
If I bolt a number of TO-247 mosfets to copper bus-bars, then using a differential gain amp to measure the voltage drop from each end of a bus-bar, I can get a current reference for input to a comparator. In the past I have used GigaVac relays as the power isolation to loads on the battery, it now seems easier to make a solid state version combined with the current sensing.
Here is a conceptual drawing of what I want to make, ideas please from anyone else...
You can go out and purchase a 48v BMS with 200-300 amp functionality, and they are not that expensive, however having seen a number that have self destructed causing fires, I don't have a lot of faith in the commercial products, prefer something that's also repairable.
Mike
Edited 2026-02-15 12:59 by Solar Mike