I have a 450w APC UPS, maybe two-three years old. Brand new I pulled the little joke of a gel-cel out of it and wired it to a marine battery. After maybe a year the marine battery went bad, so I went to the Interstate battery wholesaler and grabbed another "blem" marine (deep discharge style) battery. It's a big one, putting out around 900 cca. Well, here it is a year later and it's bad. I just now put it on a "smart" charger which said it was 11% charged. I'm condition-charging it now and it may come back to life, but I wonder... is the APC UPS incompatible with lead-acid batteries? Or maybe I'm screwing myself buying 'blem' batteries? (i've had excellent success with them in auto use) EDIT: Also, maybe someone could recommend a better UPS on a budget? Something I could snap up used off Ebay maybe?
Gel cells, wet cells and deep discharge all have different charging/maintenance requirements. Not matching the charger to the battery is always a disappointment. I'll bet that "little joke" of a gel-cell would be doing just fine had you left it alone. (And I'm not faulting you - I love to tinker with electronics myself. "Freedom isn't free", a popular quote. And sometimes tinkering isn't free).
h**p://batteryuniversity.com/ is another great site about secondary (rechargeable) systems. As for the "Pro Power" batteries on eBay, I'd think twice or do a bunch of research first. There's more junk lead acid crap than you can imagine. IMHO, you're much better off with a quality product from the likes of Panasonic or Yuasa. Unfortunately, that quality is pricey.
Using an automotive type of battery would produce hydrogen gas and sulfuric gasses too, not what you would want in an enclosed room
All good reading, THANKS! and... I did intend to put several SLA batteries in PARALLEL, it's just that I misspoke and said "series". Duh. lol
Read the UPS instructions as to what kind of battery you can use. If you do use a car battery, make sure it's the sealed, maintenance-free type, in accordance with what Joe C said.
Thank you, MS_User. Say, let me reverse my question. My riding lawn mower uses a small lead acid battery, and those go bad FAST. Is there any reason not to pop a gel cel in it? There'd be some bumps and vibration that it wouldn't see in UPS duty...