What you’re talking about now is more into smart charger and battery monitoring than battery management, really. The BMS complexity is the per-cell balancing and measurement, etc. in the analogue and A/D conversion section. I posted a link in the Dewalt thread about an open source BMS that’s out there you might consider if you need an actual BMS, but it’s not a charger (and no BMS that I’m aware of provides charging features, charging and BMS are separate roles, although some units may combine them into the same chassis). If you don’t need to manage per-cell balance, then just look at the variety of open-source chargers that are out there, I don’t have any links handy but I know there are several, and there may be programmable ones from China that use amp-counting or something else and have an RS232 API or better.