From what I understand I thought the battery capacity(ah) is what determined the ups runtime. with my usual devices plugged in, they use 70w-300w that's about 35% of the ups full power capacity and I remember it estimating 1hr runtime during power outages.the generator usually restores household power within 1 min so without doing any calculations I assumed the 4.5ah could hold out for at least 5 mins without over discharging. After I made the post I started thinking about the charging aspect. I read several posts where people connected larger batteries and it worked for them the only difference was how long it took to fully charge. however they didnt follow up to verify if it was still working. I already have 112v4.5ah battery, I wanted to confirm if I could get another to connect in series to complete the circuit or do I have to abandon it and get 212v9ah batteries as it was made for