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

[From: Igor Stoppa]

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

> it is just a point for discussion (I 
> have never seen a laptop that would not function without a battery, only 
> using external charger, however, the 770 may be quite different.)
> 
> Dave
> 
> >Message: 1
> >Date: Sun, 19 Mar 2006 13:09:34 +0200
> >From: Igor Stoppa <igor.stoppa at nokia.com>
> >Subject: Re: [maemo-developers] Re: Measuring power consumption of 770
> >To: ext Teemu Nikkil? <tnikkila at cc.hut.fi>,	scordino at di.unipi.it
> >Cc: maemo-developers at maemo.org
> >Message-ID: <1142766574.4834.19.camel at Dogbert.NOE.nokia.com>
> >Content-Type: text/plain; charset=ISO-8859-1
> >
> >Hi,
> >On Sat, 2006-03-18 at 16:17 +0200, ext Teemu Nikkilä wrote:
> > > On Saturday, 18. March 2006 13:47, Claudio Scordino wrote:
> > > > > > If I can make the 770 work with only the battery charger (using a 
> >kind
> > > > > > of bypass instead of the battery), I could use my multimeter for
> > > > > > electrical sockets to measure the power consumption of the 
> >device...
> > >
> > > In case you mean a simple kW/h meter, I doubt you will get any 
> >meaningful
> > > results with one.
> > >
> > > > > I repeat this only because you might have missed my previous advice.
> > > > > You DO want to use the battery, _without_ the charger.
> > > >
> > > > Actually I missed it...
> > >
> > > If you missed the discussion, I suggest you check it out and possibly 
> >consult
> > > someone who is into electronics and measurement technology and has 
> >access to
> > > a reasonably well equipped lab.
> >
> >I agree, I have to point out that the battery itself does a pretty good
> >job at pretending to be an ideal voltage source, therefore voltage
> >variations are very small across time and load variations.
> >And the current itself is not extremely high.
> >
> >Therefore to measure _variations_ of power consumption and also to be
> >able to tell what part of the delta is due to custom "enahncements" and
> >what part is due to the standard power saving features (both HW and SW)
> >that the 770 alreay has, one needs to have a good understanding of both
> >the 770 internals and low power measurements in general.
> >
> >Disabling the internal power saving features would render the experiment
> >meaningless, imho, because it would generate an unrealistic use case.
> >
> >If dealing properly with this sort of device/measurement is not
> >possible, I would recommend to rather focus on a laptop: it has similar
> >problems but an architecture with far less advanced power saving
> >features, both HW and SW and also uses higher power levels, therefore
> >using a meter connected to the power lines is not totally unreasonable.
> >
> >Dealing with Omap implies also having a good understanding of power
> >correlations between subsystems: arm, dsp, internal and external
> >peripherals and what the sw does to use such features.
> >
> > >
> > > I understand it is easier to do in software, though.
> > >
> > > -Teemu
> > >
> > > >
> > > > Many thanks again,
> > > >
> > > >               Claudio
> > > _______________________________________________
> > > maemo-developers mailing list
> > > maemo-developers at maemo.org
> > > https://maemo.org/mailman/listinfo/maemo-developers
> >--
> >Cheers,
> >            Igor
> >
> >Igor Stoppa (Nokia M - OSSO / Tampere)
> >
> >
> >------------------------------
> 
> 
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-- 
Cheers,
           Igor

Igor Stoppa (Nokia M - OSSO / Tampere)