If you don't have one you should.....
I have a small APC UPS on both of my computers and the batteries finally went south.
So I can get a battery from APC for around $60
Batteries Plus wants $29
But I can go to Cabelas and get a deer feeder batter for $19.
So if you need a 12v 7.5ah battery and have a Cabelas close $19 is cheap for 2 or 3 year of use.