UPS output voltage

[evilkitty]

This week i had one of my UPS units (Back-UPS 650 G1) give me some trouble (it caused my system to loose power several times, either rebooted it or resulted in it being powered off; note the BIOS is configured to boot the system when power is restored)
The battery seems fine as far as i can tell (12.5v under load), but i am only getting 90V AC when the battery is in use, 85V when there is a 75W load and the unit says the battery is good
my other unit of the same model has similar behavior but the voltage seems to go back up after dipping down (based on visual brightness of a light bulb) then my 3ed unit of a different model looks to be holding way closer to spec voltage output

i was thinking maybe the issue is reading AC voltage for a step based simulated sine-wave, but if i can see reduced performance in a light bulb of floor fan that is probably not the issue

The UPS at once point turned itself off

i can try a new battery, but is AC voltage drop expected on these units? any known common component failures that would cause this?

[CapLeaker]

Maybe due to the UPS not being a true sine inverter and you not using a DMM with RMS. This will cause the AC reading to be read low.

[evilkitty]

That was why i also did testing with a floor fan and a light bulb (75W incandescent) and i was able to see a visible drop in brightness and hear/feel the difference with the box fan

note that a 75W bub should be more current than my system uses when not running prime95...

I can't see a reason why the UPS caused my system to power cycle or why i woke up and it was powered off (like the UPS turned itself off) and i am seeing good voltage at the battery under load

my RMS meter broke, seems like a switch/dial issue but cleaning contacts did nothing, considering a Klein's CL810 or CL490

[CapLeaker]

The CL810 is superior to the 490

[eccerr0r]

PCs will sometimes spike high in current when some background task runs so you can't assume idle all the time... yeah running an intricate benchmark will set it to highest utilization and your UPS needs to be able to handle it whether or not it's a "real" task...

[evilkitty]

under a full synthetic load of all hardware you are gonna have a hard time getting a high wattage, everything is hyper optimized for low power draw well as far as i can go without modding the PSU to run off a battery directly

when i say hyper optimized i mean everything (net switch, speakers, DACs, audio amp) that is near the PC (server + VM router) that runs on 5/15v is powered from the computers PSU mainly to increase the demand on the PSU to push it higher up the units efficiency curve, the only thing that is not powered by the PSU is a piece of ubiquity hardware that uses a PoE injector (24v)

when i picked the PSU i could only find 1 better unit and i calculated the cost of running delta and if i recall it came out to needed at least 20 years of run time to break even on the price delta

i replaced the battery and left it powered in with no load devices and it turned itself off, ugh... guess i have to open it, start pulling caps, measuring caps, and make a spreadsheet, and buy new caps