[Nut-upsdev] Some questions on driver implementation and variable

[Arjen de Korte]

Peter Selinger wrote:

> how do you propose that a client should compute the battery runtime?
> That seems device specific to me. -- Peter 

Based on the same variables that the UPS is using? If this calculation
is based on any presumption (ie, a value hard coded in the driver), we
probably need to export that presumption, rather than trying to do the
calculation in the driver. I'm slightly worried about the increase in
calculated 'variables' we're seeing in some drivers. Of course we can't
prevent UPS manufacturers from generating lots of unreliable data due to
insufficient hardware, but at least we could refrain from doing the same.

For instance, calculating remaining battery capacity requires much more
than just measuring battery voltage, yet this is what we're doing in
some drivers now (and probably some UPS'es will use the same method). Of
course you'll see a nice decreasing value passing in time, but it has no
relation to the actual remaining capacity.

I would like to see a difference between values that are reported by the
UPS and values we (NUT) have calculated from these.

Best regards, Arjen