[Nut-upsuser] close pc

Arjen de Korte nut+users at de-korte.org
Sat Dec 30 18:56:38 CET 2006

>> In essence, if you're worried this doesn't work (and you should be), the
>> only way to be sure is to try it out. Power your PC directly from the
>> mains and load the UPS with a lightbulb of about 100 Watt. Pull the plug
>> on your UPS and wait. If your PC shuts down before the lamp goes out,
>> you're fine. If not, upssched is your friend and you need a timed
>> shutdown
>> after the mains is lost.
> It would probably be better to test with his PC, if he can do so safely.

If you have no idea that the low battery detection works (which is the
case the first time you try it out), you should *never* power your PC from
the UPS. You'd risk corruption of you filesystems if there is something
wrong or not configured correctly.

> Otherwise it would be better to measure how much current his PC draws
> to make sure he is testing with a large enough load.

The average user won't be able to make a more accurate measurement than an
estimate of 100W. You're not interested in the average current (which
gives you the VA rating of you PC), but rather the real power (which can't
be measured without simultanously measuring current, voltage and phase
relation between them. For an initial test, this is not needed anyway.
You'd have to test with the real load too of course, but only after
verifying that it shutsdown in this test.

>(100W might not be enough.)

An average load of 100W is sufficient for most PC systems. Power supplies
are rated for peak power, but on average your system load will be way
below that. If your PC draws much more power than that, chances are that
your UPS will not have the stamina to keep up with that for any
significant time anyway, so you'd need to shutdown before LB (batteries
degrade over time).

Best regards, Arjen

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