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Battery rapidly dying?

stoid

stoid

macrumors 601
Original poster
Feb 17, 2002
4,312
29
So long, and thanks for all the fish!
I just acquired an old clamshell iBook link, and my friend told me that when he had got it a few months ago that the battery had been rather new, and he was getting 3-4 hours of life from it. I did the terminal command to show battery capacity and it initially showed 2750 mAh. Once the battery was fully charged I set out to find out how long it would last under my normal use. Everytime I've run it off battery, when the battery gets down to 50-70% it jumps to zero and the iBook goes to sleep. Each time I've retested the battery and have gotten increasingly depressing results. The progression is as follows:

initial: 2750mAh
1st recharge: 2494mAh
2nd recharge: 2238mAh
3rd recharge: 1982mAh
4th recharge: 1726mAh
5th recharge: 1470mAh
6th recharge: 1214mAh
7th recharge: 958mAh

The iBook is running the latest version of Tiger 10.4.4 and has all other software up-to-date according to Software Update.
 
It's not looking brilliant. Calibrate the battery if you haven't already done so by default. So, let it completely run out of juice before charging it up to 100% in one go. Otherwise, give a PMU reset a go. :)
 
it would seem that what it's doing is essentially the same as calibrating the battery. I run it on battery until it forces the laptop into sleep mode, and then I charge it to 100%. Unfortunately, every calibration is stealing 10% of my battery life!

Unlesss, to calibrate this battery I need to let it run until the iBook completely powers off?
 
Yeah, you've calibrated it. It involves going past the five minute warning and waiting for the machine to fall asleep. It's not necessary to then keep trying to wake it up until the whole thing dies.

So then, did the PMU reset help? I'm not sure it'll do a massive amount of good because it really does just sound like a bad battery. :(
 
yeah, any batter dropping that fast is definetely dieing. Your friend either wasn't entirely honest with you or he used up all that was good left with the battery.
 
Well, I'm going to give the battery one more shot. It never gives me a five minute warning or any indication that the battery is low, at 50+% it just goes screen black and sleeps. As far as the honesty of the friend, I believe him 100%. I trust that when he got it, the battery was fairly new, and I know that he barely used it. Most of the time that he owned it, it was in a cabinet and completely unused. However, based on his habits, I suppose that it's likely that he would run it until it went to sleep, and then put it away and it would sit for days or weeks with a dry battery. I know that Lithium Ion batteries can be picky, so if that can kill a battery, that might be a culprit.

I talked to him about it, and FWIW during his brief possession of the 'Book, the charger plug was shorting out, and would flicker on and off. He works in an electronics shop and has used their professional equipment to fix the charger, and it functions normally now. The terminal command shows that the battery has gone through 170 cycles, and I'm wondering if that is due to the short in the cable, and if that might also be a cause of the rapid fading in battery life.

Any insights?

Re: Resetting the PMU, I'm going to do it, if the battery dies early again. I don't mind getting a new high capacity battery, since I got the laptop for so cheap, I just don't want this to be an issue with the iBook itself and that it will kill any new battery that I install too! :eek:
 
New reading on the battery now down to 1726! At least this time it made it 41% before going to sleep. :rolleyes:

For giggles I ran a linear regression on the data, and to my surprise found a r=1 match! According to the data the battery is reading 256mAh less with each recharge. Perhaps this is the limit to a battery adjustment with each calibration? I've reset the PMU and am currently charging the battery back to full again. About an hor until it's full, then we'll see if the PMU reset was effective! *crosses fingers*
 
There's also a program called.. coconut battery.. cocobattery? something like that. just look.. youll find it
 
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