I have a UPS from one of the big box stores. 625 VA. The battery has failed and I was using an 100 AH battery as the source. Lasts much, much longer. At any rate I was moving it and the battery, and touched the battery terminals and received a jolt. Turns out the battery has common mode voltage of 70 VAC on both +and- terminals measured to ground. I have no continuity from either battery terminal to either side of the AC power cord (120VAC) but typically around 128 or so. (Puerto Rico power company). I have heard of this issue on some UPS when used on floating ground A/C systems (primarily military vessels). Those UPS's are marine rated as under certain conditions 180VAC can be applied to the unit it there is a partial AC failure. I see no burned components and don't see any indication of magic smoke being released.
Thanks for any help
Jim W
Thanks for any help
Jim W