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No. of recharge cycles irrelevant?
Authored by: VicF on Mar 21, '03 01:24:51PM

Very useful information. Much gratitude to the poster. A question:

This information repeats many times that age/time by itself deteriorates Li-Ion batteries. My question is, do discharge-recharge cycles ADD to this deterioration, or is the amount of deterioration solely a function of age? Practically speaking, this amounts to asking whether it's worth it at all to avoid unplugging my laptop for short periods of time*, the hope having been that by avoiding a discharge-recharge cycle of any length, I'm prolonging the life of my battery.

* The article does a GREAT job of describing that short discharge-recharge cycles are no worse than long ones.



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No. of recharge cycles irrelevant?
Authored by: rameeti on Mar 23, '03 11:57:55AM

I'm not clear on the number of recharge cycles, but... Apple does infer
that continuous or repeated small charge/discharge cycles can impede a
batteries life. Again, in contrast to what this article infers. See the below
for my source on this.

http://docs.info.apple.com/article.html?artnum=88344



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No. of recharge cycles irrelevant?
Authored by: Winston on Sep 16, '03 11:51:41AM
The number of full charge cycles is relevant. LiIons are supposed to get about 500 full charge discharge cycles. However because of the natural degradation over time, its more likely that aging will kill the battery than use, although use is a factor. If you constantly charged/discharged the LiIon several times a day you might have a bigger influence from the charge/discharge cycles. The Apple article is consistent with my post. It says: Symptom The battery appears to stop charging between 95 percent and 99 percent. Solution This is normal. The batteries used in these computers are designed to avoid short discharge/charge cycles in order to prolong the overall life of the battery. Because of this, when setting the Mac OS X battery status menu bar icon to display charge state by percentage, you may notice that the reported charge stays between 95 percent and 99 percent. When the battery level eventually drops below 95 percent, it will charge all the way to 100 percent. There are two issues: 1. What the battery monitor says. 2. "short charge/discharge cycles" 1. The battery monitor is only an estimate. If it never gets to 100% it is because the circuit in the battery decided the battery was charged before the battery monitor got to 100%. Apple has instructions for calibrating the battery monitor which basically say charge the computer fully, use it until it goes into forced sleep, then charge it fully again. This resets the computer's battery monitor, but does nothing for the battery 2. The issue is preventing LiIons from overcharging. Once fully charged, they can't be left on "trickle charge" without danger of overcharging. As a result, they have to run down a bit before the battery's charging cycle will let them start being charged again. There may be some issue on very short charges, but the main issue is not overcharging the battery. - Winston

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No. of recharge cycles irrelevant?
Authored by: Winston on Sep 16, '03 11:53:38AM
The number of full charge cycles is relevant. LiIons are supposed to get about 500 full charge discharge cycles. However because of the natural degradation over time, its more likely that aging will kill the battery than use, although use is a factor.
If you constantly charged/discharged the LiIon several times a day you might have a bigger influence from the charge/discharge cycles.
The Apple article is consistent with my post. It says:
Symptom
The battery appears to stop charging between 95 percent and 99 percent.
Solution
This is normal. The batteries used in these computers are designed to avoid short discharge/charge cycles in order to prolong the overall life of the battery. Because of this, when setting the Mac OS X battery status menu bar icon to display charge state by percentage, you may notice that the reported charge stays between 95 percent and 99 percent. When the battery level eventually drops below 95 percent, it will charge all the way to 100 percent.

There are two issues: 1. What the battery monitor says. 2. "short charge/discharge cycles"
1. The battery monitor is only an estimate. If it never gets to 100% it is because the circuit in the battery decided the battery was charged before the battery monitor got to 100%. Apple has instructions for calibrating the battery monitor which basically say charge the computer fully, use it until it goes into forced sleep, then charge it fully again. This resets the computer's battery monitor, but does nothing for the battery
2. The issue is preventing LiIons from overcharging. Once fully charged, they can't be left on "trickle charge" without danger of overcharging. As a result, they have to run down a bit before the battery's charging cycle will let them start being charged again. There may be some issue on very short charges, but the main issue is not overcharging the battery.

- Winston

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