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.

Wayne Sallee
Wayne's Pets


Pszemol wrote on 1/29/2007 8:42 AM:

UPS (Uninterruptable Power Supply) will always be expensive
because it has advanced electronics to monitor precisely each
period of AC current and provide output without a missing power
for a milisecond. This is done for your computers/servers to not
reset when there would be some power glitch...

You do not need such advanced protection for your fish tank.
That is why a simple relay with one coil running straight from 120AC
(or if you have to use low voltage coil relay you add powerpack)
and with this cheap system you will have a moment without power,
lets say 20-50ms, time for the relay to react and switch over...
But this is ok for a fish tank. As soon as the relay switches over
your output to battery+inverter you will only be limited with the
size of the battery you get.
I have got a very large marine deep cycle battery at Walmart for
less than $80 EverStart MAXX-29. The battery is humongous.
I got it in 2003 and it still works great every power outage I have here.
All this with 10 dollar relay, 15 dolar inverter and 9 dolar charger
and some wire plus little time to assembly everything together.