[Nut-upsdev] driver for IVT SCD solar controller ?
Arjen de Korte
nut+devel at de-korte.org
Wed Jul 29 12:52:31 UTC 2009
Citeren Rainer Fuegenstein <rfu op kaneda.iguw.tuwien.ac.at>:
> there's one more thing that came to my mind, but this is also true for
> some APS UPSes IIRC:
> assume that the NUT daemon is configured to shut down the server at
> 1.52 volts. but 30 seconds later the sun comes up and so does the
> voltage as the battery re-charges, causing the SCD to not cut the
> power (which it would have done at 1.50V). this means that manually
> pushing the power button is required to power on the server again.
We don't like that. Looking at the hefty battery capacity, I would
figure that this setup is supposed to be used in a remote location
with possibly nobody around to do that.
> or: kill all services and unmount all filesystems at 1.52V (so that a
> sudden loss of power doesn't do any harm), but keep monitoring the SCD
> until voltage raises to 12.0V, then restart all services or reboot.
This is probably the only way to deal with this. The battery could
stay at the 10.52 V level for hours (maybe even days or weeks when
you're close to the polar circle), so it isn't possible to assume that
a 'power outage' is over after a couple of minutes and it is safe to
restart. So you'll have to keep monitoring the input voltage until
either the power is cut by the SCD or the voltage is high enough to
power the system again.
Best regards, Arjen
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