On 2/26/10 1:25 PM, "Don Zahniser" <[email protected]> wrote:

> I have Pismo that is behaving oddly with it's battery.  It's a 'no-name'
> battery, with a printed-on capacity of 6600mAH.  I've had it for a
> couple of years; it came with a Pismo that was bought as a Christmas
> present for me by my Lady Technophobe.  Utilities such as coconutBattery
> do not read an original capacity for it; It currently shows a capacity
> of 4128mAH - and I don't think it has really been much better than
> that.  Also - none of the utilities that read out the number of load
> cycles display anything but zero.

I don't think that the Pismo supports cycle count.

> Now - the odd behavior:  When running from battery, I get about 2 hours
> of steady use with Airport on - no problem with that, I suppose.  The
> oddity is that when the indicated capacity drops below about 30%, the
> computer suddenly goes to sleep without any warnings.  When I
> immediately plug it in to the AC adapter, the capacity shows as 0%, and
> climbs steadily. 
> 
> I thought that the battery should drain further before sleep, and that I
> should have at least one warning pop up beforehand.

This sounds a lot like what was happening with my old Pismo battery. Based
on my experiences, the problem is not with the computer but with the
reported capacity of the battery. Your battery is reporting a capacity of
4128mAH, but I would suspect that the actual capacity is about 70% of that.
You don't get the warnings because the Power Manager thinks there's plenty
of life left and then gets blindsided when the power runs out.

In my case, I noticed that each time I fully discharged the battery, the
reported capacity would drop by a couple of hundred mAH, but the percent
remaining would also go a little lower each time. Eventually, the capacity
stopped dropping and the percentage would track to the actual battery life
left (with appropriate warnings).

In other words, nothing is wrong except that your battery is getting old and
a few discharge cycles should bring it back in sync.

John



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