It's just an AGM lead acid battery and a charger. I pulled the charger out of an old RV. I estimate I'll get over 10 hours runtime from it, since I used a 115 amp hour battery..
Oh, do tell about your UPS. Self made, off grid or some sort of busted gear hack? 12V DC is like telco lite (typically 48V)
A few solar panels wouldn't be hard to add, but I'm not currently running off grid.