Re: battery life
To continue the battery discussion...
>> http://docs.info.apple.com/article.html?artnum=14449 i read it very
>> quickly, but it might be useful! it describes how to reset the pmu
Resetting the PMU didn't hange anything for me. I think resetting the
PMU can help when you're unable to use your battery down to 0% capacity;
which happens on the iBook, but AFAIK not on the PowerBook.
The problem I'm facing is loss of capacity in the battery.
> Another interesting read is this:
>
> http://docs.info.apple.com/article.html?artnum=88344
>
> The text talks about how batteries stay at between 95% and 99% charge
> even though AC is plugged in. The reason Apple gives for this expected
> behaviour is:
>
> 'designed to avoid short discharge/charge cycles in order to prolong
> the overall life of the battery'
>
> which is the first confirmation I've seen that indeed the number of
> charge cycles is one factor limiting battery lifetime.
I've not found confirmation of this in the battery manufacterer's
literature. However, I've come across charge/discharge cycle lifetime
indiactions varying between 300-500 (full discharge very time) an over
10000 (discharging only down to 17% capacity).
That would mean that a full discharge _is_ worse than a half discharge.
I've also tried to see how long the TiBook runs when I disable pmud, so
that it continues even though the battery indiactes 0% charge. Well, it
goes on for some time... I stopped it after 10 minutes or so, because I
was afraid of a deep discharge of the battery (below rated
end-of-discharge).
Indeed, I did regain a few percent of max_charge:
pooh:~# cat battery-life
20030101 max_charge : 2376
20030302 max_charge : 2145
20030322 max_charge : 1774
20030323 after deep discharge max_charge : 1814
What I will try is do another deep discharge with pmud disabled and
monitor the battery's voltage (it's indicated by pmu, unit is mV). I'll
probably go down to 12 V, i.e 3.0 V per cell, which is what most
manufacterers indicate as end-of-discharge voltage. The intent here is
to recalibrate the smart battery controller's idea of max_charge.
We'll see... If anybody has a TiBook-I battery pack to open and look at
the exact type & model of battery cells, that would help as well :-)
Cheers
Michel
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