[Nut-upsuser] Fwd: Cyberpower usbhid-ups wrong battery voltage

davor emard davoremard at gmail.com
Fri Apr 11 10:56:35 UTC 2008


IMHO everything that measures something should be subjected
to periodic calibration being it a 5-digit precision laboratory voltmeter
or cheap piece of junk like ups, both can benefit from being
calibrated with higher precision instrument (not only to improve
measured values but also to determine the errors and repeatability
of the measurement)

Hopefully the model detection will make it and at least the coarse
conversion factor would be there for cyberpowers and others that
need it.

If calibration has no place in your config files I'll do it in my application
and I can live with 21V "voltage" for 12V battery reported by it's HID

Best regards, Davor

On 4/11/08, Arjen de Korte <nut+users at de-korte.org> wrote:
> [...]
> > So everybody can calibrate his own ups battery measurement
> > make the polynomial fit and just enter the coefficients in
> > ups.conf or just use recommended values for some models
> > that are know to have systematic error
> >
> > what do you say?
> I don't think this is a good idea. A UPS is not a measuring instrument.
> The accuracy and resolution that can be achieved is magnitudes away from
> what would be needed to *really* make meaningful measurements.
> Making this user configurable is not an option, since for most if not all
> USB devices, we'll probably remove this once we've ironed out some things
> regarding the detection of the devices by the server.
> Best regards, Arjen

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