> Do any of those UPS systems have the ability to signal, say... 5 or 10
> minutes before they would run out of power?  something like that?  I'd
> almost be afraid to guess at a time and count down from there, because
> batteries do degrade over time, and with my luck, the system wouldn't go
> down in time.  All it would take is once....   :-)

I think the idea might be just take the "we've switched to batteries"
case as the right time to fire off the shutdown. Take the count down
time as zero. :-)

The best bet here depends on why you want to UPS, and what kind of
power losses you expect. If you expect mostly temporary flickers,
then some sort of "wait for X %" would make sense. But I'd expect
most power failures to be of the blackout variety, so just shutting
down as soon as you get a power loss would make sense.

Take care,

Bill