"charles" wrote in message
...

My UPS - an ebay purchace - is an APC one and it self-tests its battery.

Actually I've got 2; one for my desk computer monitor and a small one form
the incoming FTTC router.

Ours was an APC - I think it was 700 VA. I've no idea how long it was
*supposed* to power a computer for - presumably at least long enough to
trigger and complete an orderly shutdown of the OS. In my case, the answer
was "a few microseconds for a 60 W load" :-(

Annoyingly, my router and computer are in separate rooms so I'd need two
UPSes like you. Hopefully any modern UPS is able to provide a glitch-free
transition from mains to battery, otherwise it's no benefit because the
computer will still crash during the changeover, even if it then comes back
for while until the battery goes flat or the mains comes back.

In our case, almost every power interruption has been for about 5 seconds -
I think only one was for as long as 5 minutes: just long enough to feel my
way in the pitch dark from my study through the lounge and kitchen to the
bedroom where I knew there was a torch. And just as I got there and turned
it on, the power came back.