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

[Arjen de Korte]

>> On 2/25/07, Arjen de Korte <nut+devel at de-korte.org> wrote:
>> >Based on made up 'information'. I'm not doubting your good intentions
>> >here, but I'm quite worried that we're on a slippery slope. I'd rather
>> >not present data if we're not sure it is reliable.
> what makes you think the (not always present) calucation in the UPS
> firmware is any better?

I don't think that. For what it's worth, I have not much trust in anything
other than the OL, OB and LB states reported by just about any UPS. Unless
you have a nice (and reasonably stable) load and use runtime calibration
every month or so, calculating runtime left is mostly guesswork.

> your trust in embedded software is heart-warming, but totally
> contradicted by reality.

I have slightly more trust in the embedded software, than the underlying
hardware that is used (which means, not much for either). That doesn't
mean I think the values reported by UPS'es are more accurate than what we
might calculate, although theoretically the algorithms used may be more
accurate than what we might come up with. There is nothing we can do about
UPS'es spitting out inaccurate (or even completely bogus) values, I just
think we should refrain from doing the same.

There probably is some merit in knowing an approximate value for the
battery charge, other than just reporting the OB and LB state. Some
applications may be wanting to shed part of the load based on charge left
to optimize runtime. However, I think that is probably where we should
stop.

Best regards, Arjen
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