KurtG wrote:

Wayne Sallee wrote:

Another thing that can be done is to hook up a car battery to your ups
for longer running time. You could even hook up as many batteries as
you like.


I've never seen a UPS with a 12 volt hook up. I use APC's and even have
a 80# version w/ no hookup.

I was looking into a power failure relay, but haven't made much
progress. I think I'll just build my own as I've been thinking of a
battery bank anyway for other reasons.

--Kurt

The "extended run" or "XL" series UPS'es that APC makes have hookups for
extra external batteries. Of course they are inteded for their APC brand
extended run battery packs (which cost an arm and a leg) -- but I bet
that one could hook up any old 12 volt lead acid battery...