Electronic geek question about UPS batteries?

my ups is going on 7 years old and still runs strong as it was when new but no, do not use a marine or car battery. They can leak fumes that are explosive and highly poisonous. yes, even the sealed ones.

a lot of people in asia use ups systems with car batteries. but you need a seperate controller, similar as those for solarchargers and a car battery charger. your ups can't charge the big ones! do a search in internet for DIY ups

Wow. Thanks for the fast and good answers.

UPS batteries are the same chemistry as sealed marine batteries. Two issues arise. One is charging current. The UPS can't charge a battery much larger than it's designed to. 20% larger shoulda be fine, though. Many large UPS systems have a connector to add an extra battery though, and those are designed for the extra current.

The other issue is discharge current - a larger battery will let the UPS run longer, but won't let it run more equipment. A UPS designed to power one desktop for ten minutes can NOT safely power three desktops for three minutes. Therefore adding batteries or using a larger battery only means it can run longer than ten minutes. That really doesn't do you a lot of good. After five minutes, the power probably isn't going to come back on any time soon, so it's time to shut down. Neing able to run from UPS for twenty minutes instead of ten just doesn't do you much good.

Despite the caveats mentioned above, many people do it, uating a deep cycle marine battery. Car batteries are designed to price a lot of power for a few seconds to start a car. Boat batteries are designed for longer use. You should make sure the battery is fully charged before connecting it so the UPS doesn't have to charge that big battery, just keep it charged.

You should have a fuse installed at the battery terminal and use a battery box with a small fan added to catch any leakage while dissipating any fumes.

Just spend the extra $30 and get a UPS...

Thanks for the additional information.

I have a UPS for laptops that runs each of my weather stations, add to that a bigger battery and I can capture and transmit lots more data. The more brutal the outage created by a storm, the more important the capture and transmit of data is!

Just checked the "status" and it shows 14 "blackouts", and 4 electrical noise events in the past 20 weeks.