I have a Powercom PCM Black Knight UPS (600AP model). It seems to work perfectly as a UPS, but the computer monitoring is a little off.
For example :-
1) The battery is reported as "92%" full, and no more. The terminal voltage is fine, but it never charges more than 92%.2) The mains voltage readout claims that the incoming mains is 216.4v at the moment, but really it's 238v. It's always about 91% of the actual value as confirmed by a DMM, a plug in power meter, and another UPS.
3) When it's on battery, the outgoing mains voltage shows as 216.4v, when the inverter is actually producing a perfectly good 238-240v.Now, I'm hoping that the fact that these figures are off by very similar amounts means that somewhere, an A-D conversion circuit is a bit off, and can be tweaked. Does anyone have a schematic to indicate which of the various adjustment pots would do this? Or is it a "fixed at design" thing?
Also, it measures "power loading" as 17%. When placed onto battery, the power loading initially was around 15%, descending to 3% over 20 mins. When returned to mains operation, loading stays at 3%, and rises back to 15-17% over the next few hours. Huh? That's harder to understand, as the load on it is pretty constant 85VA/51W (as measured), which would be about 14%. It's almost as if the power loading measurement depended on the 12v battery voltage for accuracy. Which would be bonkers ...
Mike.