[Surferdude] was unhappy with the decreasing life of his aging uninterruptible power supply. He decided to beef it up using marine batteries. He extended the battery connections outside of the UPS case using #10 wire and swapped the two 12 volt gel cells with the heavy duty lead-acid batteries. Doing so upgraded the device from 20 amp-hours to 84 amp-hours at a cost of about $160. If you’re thinking about taking this on yourself, pay attention to the countinuous output rating of your UPS to prevent a fire risk.
Beef Up Your UPS
Keep it cool and it will work. Twelve volt chassis fan with relay on in backup only or full time with dust magnet mode. Most of these things were meant to run a big ‘ole CRT. Now were are flat screen.
Warning!
No one has pointed that some UPS’s have line potentials to ground on those low voltage connections at the battery! They will caution you on labels. Legal underwear. So your car battery can be powerline hot to earth!
Insulate like hell.