On May 11, 11:56*am, "William Sommerwerck"
wrote:
I don't want to discourage the OP from trying to recharge the battery -- be
sure to cover them with something thick and heavy, in case they rupture or
explode (I'm not trying to be funny)

No reason to remove or disconnect those batteries. Simply connect a
VDC multimeter to battery terminals. If voltage rises when UPS is
connected to AC, then UPS charger is working. Same charger test
performed without removing anything also tests other UPS hardware.
Procedure tests both items simultaneously. Learn more, faster, by
also doing less labor. Use a meter.