[Nut-upsdev] sign of battery.current

[Arjen de Korte]

Citeren "Kiss Gabor (Bitman)" <kissg op ssg.ki.iif.hu>:

>>> What is the sign of battery.current value?
>>> I wonder if the negative number means charging or discharging.
>> Most drivers that use battery.current, a positive value means  
>> charging. It is
>> extremely rare that discharge current is reported, but the few drivers that
> I'm confused a bit. You swapped the words, don't you?

No, see above. You asked for the sign of the 'battery.current'  
variable. If this is reported, this usually is the charging current.

> The discharge current is always(!) reported.

I only know of one driver that reports the discharge current, so it's  
hardly ever reported (measuring high currents with any kind of  
accuracy is relatively costly). Typical consumer grade UPSes won't  
report the charging current either, although medium to high end UPS  
devices will usually report this (since it can give you an idea of the  
health of the battery if measured over time).

> By definition
> * charging (in OL state):    energy stored in the battery is increasing.
> * discharging (in OB state): the load consumes stored energy.

Irrelevant, this has nothing to do with the 'battery.current'  
variable. Even the most basic contact closure UPS device should  
support the OL/OB/LB *state*, but this doesn't mean they also need to  
report the actual *value* of the current that is going into or out of  
the battery (usually, it is irrelevant to users anyway).

> I just asked because KNutClient displays a meter with scale
> -15..+10 Amps however (absolute value of) charging current is
> tipically lower than discharging.

This nicely follows the fact that the charging current (+) is usually  
smaller than the discharge current (-).

Best regards, Arjen
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