UPS with external battery


New member
I'd like to add a UPS to my system so that at least the circulation pump would work in a blackout. Outages are rare here but usually don't last more than a few hours. I've read about hooking an external marine battery to the UPS to extend the backup time, but I can't seem to find a UPS that will accept a 12 volt external battery hookup. Some of the larger UPSs that I have found in surplus (for cheap) need odd voltages like 32 volts. Can anyone suggest a UPS or brand that will accept a 12 volt external input?


New member
Do an internet search for Durso standpipe. You should find the aquarium website for Mr. Durso. On his site are extensive details about 3 different power back up options for aquariums including UPS and a DC/AC converter with a car battery. I think he even has model numbers posted.


New member
I thought about running 3 batteries in series, but then I would have to buy 3 batteries at $75 each! Our power outages are infrequent and have never run more than 6 hours.


Premium Member
1) You need a true sine wave output
2) You need to know what the wattage of the pump is
3) you can then determine what size of UPS, and how many external cells you will need to power the UPS.

You will want to overshoot your minimum runtime calcs by about 60% to account for battery degredation over the life of the cells (18-36 months typical).