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battery charge behavior

Message #1 - Posted 2003/08/28 - Susan Hall

I have a 1.5 year old 15" Powerbook. When new, the battery would top off its charge when the level dropped to below 95%. Now, the level needs to drop below about 83% before it re-charges. Another difference is that the light on the charger used to glow green when it was in that state (below 100%, but not charging) - now, it glows amber. I'm not complaining, just wondering if someone has an explanation.

I rarely use it on battery. I'll go for days at a time just carting it asleep between work and home and plugging it in as soon as I arrive. So it's spending a lot of time in the amber state as it slowly falls from 100% to 83% during the commute intervals.

Thanks,
Susan

Message #2 - Posted 2003/08/31 - slavins

Previously, Thomas Reed wrote:

Previously, Susan Hall wrote:

I rarely use it on battery. I'll go for days at a time just carting it asleep between work and home and plugging it in as soon as I arrive. So it's spending a lot of time in the amber state as it slowly falls from 100% to 83% during the commute intervals.

You probably need to recondition your battery.

Possibly not: a 1.5 year old 15" PowerBook probably has a Lithium Ion battery (you can check it, Susan, it'll be on the label if you take the battery out of the PowerBook). These do not have the 'memory' characteristics associated with the Nickel-Cadmium system used in earlier rechargable batteries.

However, if you keep them at full charge for a long time they do gradually lose their capacity. So what I'd recommend to Susan is that she try letting the battery discharge once a week or so: take it home or to work as normal but don't plug it in until it gives the low-power warning. If they battery can last a whole office-time or home-time without recharging, so much the better.

Note that LI batteries aren't really expected to last longer than three or four years anyway: they have both a limit on lifetime and a limit on the number of charge/discharge cycles they can go through (about 3,000). Your pattern of use involves two charge/discharge cycles a day which is what's causing your problem.

Message #3 - Posted 2003/08/31 - Thomas Reed

Previously, Simon Slavin wrote:

You probably need to recondition your battery.

Possibly not: a 1.5 year old 15" PowerBook probably has a Lithium Ion battery [...]. These
do not have the 'memory' characteristics associated with the Nickel-Cadmium system used in earlier rechargable batteries.

Well, I know I read somewhere -- I think in the docs that came with it -- that the battery in my brand new PowerBook G4 should be completely drained (to the point that the machine puts itself to sleep) and then recharged if you notice that the battery life has shortened.

Message #4 - Posted 2003/09/03 - Susan Hall

Thomas Reed wrote:

Susan Hall wrote:

I rarely use it on battery. I'll go for days at a time just carting it asleep between work and home and plugging it in as soon as I arrive. So it's spending a lot of time in the amber state as it slowly falls from 100% to 83% during the commute intervals.

You probably need to recondition your battery. Use the machine unplugged until the battery is totally drained. (That is, until the machine goes to sleep because the battery is too low to continue working.) At that point, plug the battery back in. I think that doing this once ought to do the job, but it couldn't hurt to do it two or three times, and then repeat it every 3-6 months.

I keep reading that Lithium Ion batteries don't need reconditioning (mine is one), and yet the other day I let it go on battery down to 40%, and now at least the light is back to glowing green instead of amber at 98% on the way down again. I'll soon see at what % the charger kicks in.

I did run the battery down to sleep when I got the machine as described in the booklet (I almost said manual, heh), and down almost to sleep a couple of other times since I've had it.

Susan

Message #5 - Posted 2003/09/04 - slavins

Previously, Thomas Reed wrote:

<slavins@hearsay.demon.co.uk wrote:

You probably need to recondition your battery.

Possibly not: a 1.5 year old 15" PowerBook probably has a Lithium Ion battery [...]. These
do not have the 'memory' characteristics associated with the Nickel-Cadmium system used in earlier rechargable batteries.

Well, I know I read somewhere -- I think in the docs that came with it -- that the battery in my brand new PowerBook G4 should be completely drained (to the point that the machine puts itself to sleep) and then recharged if you notice that the battery life has shortened.

I would be interested in the source if you ever find it again. Totally draining a Lithium Ion battery is not good for it.

Message #6 - Posted 2003/09/04 - John Johnson

Previously, Susan Hall wrote:

Thomas Reed wrote:

Susan Hall wrote:

I rarely use it on battery. I'll go for days at a time just carting it asleep between work and home and plugging it in as soon as I arrive. So it's spending a lot of time in the amber state as it slowly falls from 100% to 83% during the commute intervals.

You probably need to recondition your battery. Use the machine unplugged until the battery is totally drained. (That is, until the machine goes to sleep because the battery is too low to continue working.) At that point, plug the battery back in. I think that doing this once ought to do the job, but it couldn't hurt to do it two or three times, and then repeat it every 3-6 months.

I keep reading that Lithium Ion batteries don't need reconditioning (mine is one), and yet the other day I let it go on battery down to 40%, and now at least the light is back to glowing green instead of amber at 98% on the way down again. I'll soon see at what % the charger kicks in.

[snip]

Note that your battery's actual state of charge is controlled by the on-battery charge controller, and you won't affect it's limits on state-of-charge by draining and charging the battery. All you do is re-set your display. This would be rather like re-calibrating your automobile fuel guage by running the thing out of gas, then filling it up completely. You haven't changed the size of the tank, only the accuracy of the guage by knowing exactly where full and empty are).

Li-chemistry batteries don't get "memory effect." Under the conditions where a Ni-chemistry battery would have this happen, a Li-chem. battery would likely catch fire. The on-battery charge controller is there to prevent this.

Message #7 - Posted 2003/09/07 - slavins

Previously, Joe Heimann wrote:

http://docs.info.apple.com/article.html?artnum=86284

Apple only calls for this to be done every few months, not on a regular basis such as once a month. Hope this helps.

Many thanks.

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