Instructables

Make your computer UPS last for hours instead of minutes

Step 7: Attach to battery, and test

Next, attach your battery terminals to the battery, and then your wires to the terminals.
Insert a fuse in the fuse holder.
And turn on your UPS.
It will take a long time to charge the battery, but it will also last for a long time in a power outage. Under this setup mine lasted for around 1.5 hours.

Be sure to put the battery in a plastic case with a lid, as, if something were to go wrong on the battery you would want to contain the acid as much as possible. Also, this will prevent you from dropping something and shorting out the battery.
 
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Zerocool8183 years ago
I would ( if i do this) use sealed lead acid batteries you know they have a reason to use sealed ones: they are smaller lighter and safer and can give you more charge cycles and longer run time and they are cheaper you can get some sealed scooter batteries for 20 dollars online and they are like 50 amps each and two of them can fit in the place of one of yours and have you considered using computer fans to cool the inverters so they dont get damaged? wow that was a mouthful. nice setup anyway!
farna4 years ago
If you don't need quite as much power as a car battery, consider a lawn tractor battery. Same type as a car, just smaller. A motorcycle battery would work, but most of them have about the same power as the original UPS battery.

The main caution with ANY automotive type replacement battery is that hydrogen gas is produced when charging (only small amounts when trickle charging like this) and they have liquid acid inside. Make sure they don't get tipped!!
tariqa035 years ago
so i dont need to change my existing charging unite of the UPS
ben.mcfadden (author)  tariqa035 years ago
If your UPS currently uses a 12V sealed lead acid battery, it is 100% safe to hook that same charging circuit up to a standard car battery. It will, logically, take far longer to charge this car battery than the small lead acid battery, but it will work. If your UPS uses a 24V sealed lead acid battery (OR two 12V batteries wired in SERIES), you will need to hook it up to TWO car batteries wired in SERIES.