[ltp] Re: [PATCH v2] Re: Battery class driver.

Pavel Machek linux-thinkpad@linux-thinkpad.org
Thu, 2 Nov 2006 23:01:45 +0100


Hi!

> Well, "Wh" measures energy and not power, and "Ah" measures electric charge
> and not current, so it would be better to make that:
> 
> capacity_*_energy  (Wh-based)
> 
> and
> 
> capacity_*_charge  (Ah-based)
> 
> Also, should we go with mWh/mAh, or with even smaller units because of the
> tiny battery-driven devices of tomorrow?

Okay... So I have cellphone here, 700mAh battery, ~2.8Wh battery. It
could last 14 days if we were *very* careful. 

echo '(700 mA * hour) / (14*day) \ A' | ucalc

ucalc> OK:  0.002083
ucalc>

...that is about 2mA in low power standby mode (but still listening on
GSM, getting calls, etc).

...so, mAh are probably good enough for capacity_*_charge, but would
suck for current power consumption, as difference between 2mA and 3mA
would be way too big. We need some finer unit in that case.

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html