I use an APC 1200 UPS and have it connected to two external car
(actually marine/starter) batteries. This is a 24v system. This has
worked reasonably well for me but for the past 7 years, but I have used
batteries that require water....and when I forgot to refill them, they
would dry out. I am now using a maintenence-free battery, and will see
how long it lasts.

Also, I originally used a deep cycle battery but I think a regular
starting battery would be better. We seldom have blackouts so the
battery would almost always be at max charge. This is what normal car
batteries are designed for. Of course, your situation may be different.

If I were you, I would just get a large car battery and try it....they
only cost $35-45 at Costco. I can't imagine a UPS failing because it
was only designed to run for a few minutes.....but who knows. I have
run my UPS for well over 10 hours straight with no problems...but it has
a cooling fan that kicks in.
cv





Mark wrote:

if you are OK with using external batteries ,

a car battery is probably your best deal...

just be SURE to properly fuse it in case something fail or the wires
short.... ....


Mark