Originally Posted by
disaster999
Im sure theres more than "just a BMS for the battery". There must be some logic and voltage and current detection and power switching from battery and AC power. It needs to keep the battery at a low charge all the time in order for it to be ready to accept charge back from the charger and be intelligent enough to switch to AC power when the battery voltage drops too low.
A decent BMS with maybe a relay activated by the PSU to switch the battery between a load and the charger can do that, I doubt he has designed an own circuit board doing that.