On Thu, 6 Aug 2020 09:15:42 +0100, No Name wrote:

My choice of UPS make would be APC.

I'd look very hard at other makes before getting another APC. They
have (had?) a habit of cooking the batteries. Meaning that they'd be
knackered enough after 4 years to make the runtime, even at low
loads, rather too short, read tens of minutes rather than half a
dozen hours. I got ****ed off at this "feature" and attacked mine 5
years ago to reduce the charge voltage and fit a fan. The new
batteries fitted at that time are still good. Yes, it takes longer to
reach the 15% capacity switch on point after switching off due to low
battery but I'm not getting through batteries...

So a UPS typically gives you a grace time of say 5 to 15 minutes before
it shuts down ...

That runtime is normally quoted for full load.

... as if you discharge the batteries too far, the battery lifetime is
shortened.

A decent UPS won't let you discharge the batteries too far. B-)

If you are running your UPS for that length of time, The UPS's inverter
and batteries will be getting warmer than would be typical which will
certainly affect the lifetime and reliability of the UPS.

That length of time at full load. Mine is sat at 10%, around 50% of
that is the HP Microserver. 2 minutes after the supply fails the
server shuts down and switches off (UPS is there to maintain the VOIP
phones rather than full net access). The UPS happily runs at 5% ish
for hours...

If this is not feasible at the location of teh UPS, you can use a
raspberry Pi with some UPS software on it and then you can SSH or Putty
or remote desktop into the Pi to check up on teh UPS state and reporting
logs.

But not gracefully shutdown "remote" computers unless they get their
power from that UPS or other maintained supply.

230 V AC mains to DC battery charging within the UPS
DC to AC inverter within the UPS
Then 220V AC to DC conversion via the various wall warts to the IT kit

vs

Car battery trickle charger from 220 V AC to 12V DC

Then a bank of LM317Ts set to the required DC voltages to the router,
ONT, Wifi AP thereby bypassing the wall warts entirely

This is one conversion efficiency loss only vs 3 sets of conversion
efficiency losses.

Two losses, your fogetting the DC-DC conversion via a very lossy
linear convertor, especially for 5 V devices. You could mitigate that
a bit by using a switching DC-DC convertor.

You can even wire two Honda generators in parallel via a kit and have an
automatic start device in case of a power loss. An ordinary UPS can then
cover the transition between grid power and locally generated power.

Not quite as simple as it sounds, the generator needs to start, run
up to speed and stabilise before its output is switched to the UPS
input. I dread to think what UPS would make of being fed from a
genset as it starts.

A genset also opens up a whole raft of worm cans regarding connecting
a genset to the premesis wiring, earth requirements, not back feeding
the grid, etc.

--
Cheers
Dave.