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Discontinuities in charge profile
Authored by: VicF on Mar 14, '03 02:02:56AM

So, I used X-Charge to follow the charge profile of the battery in my GHz TiBook through a complete discharge and recharge cycle (nice little program, BTW). During the discharge cycle, my battery declined consistently until it got to about 15%, and then without warning, it plunked immediately down to 0%, forcing the PowerBook to sleep. I then plugged in, and the battery charged reasonably quickly to about 80%, at which point the rate of charge started to slow. It climbed quite slowly to about 86%, and then jumped immediately to 100% and (obviously) stopped charging.

So, what do these jumps down and up mean? Should this battery be recalibrated? Does resetting the PMU do that? (If I run the little bash script, I get "voltage=16751 flags=5/0x005 amperage=4 capacity=4096 current=4090 [99.9%]".)



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Discontinuities in charge profile
Authored by: Winston on Mar 14, '03 07:57:52AM

LiIon batteries have a built in circuit that limits overcharging and run-down. Overcharging can cause the battery to overheat (i.e. catch fire) as well as damaging it. Running it down too far also can cause charging problems. Maybe what you are seeing is caused by the protection circuit.

Apparently the protection circuits cause a lot of problems tooccur with "good" LiIons, for example an undercharge circuit that kicks in and won't let the battery charge.

Also, LiIons degrade over time whether you use them or not.

More info on all battery types here:
http://www.buchmann.ca

summary on LiIons here:
http://dealmac.com/forums/read.html?f=1&i=1092115&t=1092077



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