In most of BBS cabinet for the RBS 2116 when the battery less them 22 volt the BFU will not charging the internal relay inside the BFU will not get order from the microcontroller. I had make a physical thing let it charging but if any one use it and don’t know how may be it coast to burn the BFU so sorry I can’t speak about it but for me it work 100% also I the new version from omt 35-4 it can configure the 4 psu in 2116 cabinet thanks all .
Best regard
jamil el banna