[maemo-developers] [maemo-developers] Re: Measuring power consumption of 770

[From: Igor Stoppa]

Hi,
On Tue, 2006-03-21 at 09:33 +0100, ext Frantisek Dufka wrote:
> Hello Igor,
> 
> can you comment on idea mentioned in this thread about charging the 
> battery fully and then measuring DC current from charger? Is this 
> nonsense or not? Is the battery used when already charged and device is 
> still connected to the charger? I thought most laptops and PDAs work 
> this way i.e. disconnect battery and use only power from AC adapter. How 
> 770 works? Or is there other issues except those already mentioned? One 
> potential issue is that power saving features may be turned off when 
> charger is connected so the device requirements may be higher than when 
> using battery.
let's say that if I were to do this measurement, with a production
device, I would do it without the charger. About other devices, I'm
sorry but I don't think I'm the right person to give detailed comments.

You might want to try on the linux-pm mailing list where there are many
people dealing in linux on laptops.

Anyway I think that to avoid flaws in the comparison between vanilla 770
and 770 with extra power saving algorithms, the measurement should be
done in the typical condition that the device is intended to be used
mostly: disconnected from the power socket.

This test should be done anyway, before claiming that the algorithm is
effective.

And disabling native power saving features is reasonable only when
developing an algorithm that is intended to be a replacement, but the
one mentioned at the beginning of the thread was only for data transfer.

Maybe a laptop would benefit more from this stuff than an embedded
device.

igor
> 
> Frantisek
> 
> Igor Stoppa wrote:
> > Hi Dave,
> > On Mon, 2006-03-20 at 11:00 -0700, ext david feldman wrote:
> >> Will the 770 run with the recharger (or other external DC power source) 
> >> attached, with the battery REMOVED? This could be same as the case of an 
> >> expired battery that will no longer accept a charge. In this case, the only 
> >> power consumed by the 770 would be by the machine itself, not by the battery 
> >> recharge, nor assited by battery discharge.
> >>
> > Unfortunately I cannot comment on this issue because it has _strong_
> > liability implications: when dealing with the battery there might be
> > potential safety issues, in case of abuse, overcharging and so on,
> > therefore it's one of the few subjects that cannot be discussed openly.
> > 
> >> I have not tried this idea, and it could cause unit damage or malfunction, 
> >> so I do not recommend the procedure - 
> > 
> > Exactly, that's the point. And that's why there are safety mechanisms
> > that will get in the way when trying to counterfait the battery.
> > 
> > The original conversation was about validating power saving algorithms
> > and I was trying to help doing it without safety features becoming an
> > obstacle. The simplest solution is to use an original battery and wire
> > it to the connector pins. 
> > 
> > igor
> >