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.
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Mike Brown: mjb[at]pootle.demon.co.uk | http://www.pootle.demon.co.uk/

After these batteries have a few years on them, they may not be fully
charging. A simple voltage test will not reveal the true condition of
the batteries. A proper load test is necessary to make evaluation.

The batteries should be properly load tested before making any
assumption. We install new batteries to make a simplified evaluation.

The manufacture of your UPS will not supply any service information or
parts to non authorised service people.

Jerry G.

In article om,
Jerry G. wrote:
After these batteries have a few years on them, they may not be fully
charging. A simple voltage test will not reveal the true condition of
the batteries. A proper load test is necessary to make evaluation.

The batteries are new, and are fully charged (I did say the voltage was
correct for a 100% charge, yet reported as 92%). They have been load
tested in-situ, it ran for over 20 minutes before graceful shutdown.

They've also been externally tested, and are as I would expect.

The manufacture of your UPS will not supply any service information or
parts to non authorised service people.

Yes, I'm well aware of that, just hoping that someone might have service
info to help me correct the fact that the mains voltage readout is skewed.

I don't want to have to get into returning the unit as "faulty", as it
works fine other than an inability to correctly read out its own battery
voltage and incoming/outgoing mains voltage, by a factor of 91-92%. It's
still in warranty and has done this from new, so it's not a fault that
has developed, it's always been off calibration.

But I suppose it's one way to sort it out. Not my preferred option.

Mike.
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--------------------------------------+------------------------------------
Mike Brown: mjb[at]pootle.demon.co.uk | http://www.pootle.demon.co.uk/