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Mac OS says battery is "charged" at 99%

W

WillMak

macrumors 6502a
Original poster
Jul 29, 2005
957
0
My battery charger is stuck at 99% (I just got the ibook) for the past 2 hours. I've seen it hit 100% before but for some reason it's stuck at 99% C'est normal?
 
Yep, normal. Don't worry about it. It's just making sure it doesn't overcharge itself and blow itself up. It won't charge again until it drops to about 95% from memory. :)
 
mad jew said:
Yep, normal. Don't worry about it. It's just making sure it doesn't overcharge itself and blow itself up. It won't charge again until it drops to about 95% from memory. :)
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!?!!? So it's going to charge the battery again when it drops to 95%? Doesn't this kill the lifetime of the battery!?!!?
 
No, quite the opposite. It means that the battery only has to charge itself very rarely (if left unused) as opposed to if that threshold were closer to 100%, in which case the battery would have to stop and start charging very often.
 
As long as you fully discharge (force the laptop to go to sleep) the battery every month and then recharge it to full (between 96 and 100%, depending on how OS X feels that day), then the battery will maintain its life for quite a while.
 
crazzyeddie said:
As long as you fully discharge (force the laptop to go to sleep) the battery every month and then recharge it to full (between 96 and 100%, depending on how OS X feels that day), then the battery will maintain its life for quite a while.
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Great tip, thanks. I going to start to do this, learn something new on MR everday :)
 
DeSnousa said:
Great tip, thanks. I going to start to do this, learn something new on MR everday :)
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That's not actually what Apple says:
Standard Technology
Lithium-ion batteries pack in a higher power density than Nickel-based batteries. This gives you a longer battery life in a lighter package, as Lithium is the lightest metal. You can also recharge a Lithium-ion battery whenever convenient, without the full charge or discharge cycle necessary to keep Nickel-based batteries at peak performance. (Over time, crystals build up in Nickel-based batteries and prevent you from charging them completely, necessitating an inconvenient full discharge).
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itchster said:
it does not harm it to do a full charge cycle every month though right? so what's the harm?
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The harm is, according to Apple, that if you charge your laptop 3% a day, it'll take 30 days to complete one charge cycle. If you then run it down completely and recharge, you're just using up another cycle for nothing: each battery only has so many cycles in its lifespan.
 
skunk said:
The harm is, according to Apple, that if you charge your laptop 3% a day, it'll take 30 days to complete one charge cycle. If you then run it down completely and recharge, you're just using up another cycle for nothing: each battery only has so many cycles in its lifespan.
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There's a lot of contradictory stuff about this. I'd been calibrating my battery about every 4 months when I remembered but the Genius Bar told me I should be doing it every month. I've compromised and do it every 2-3 months.
 
Lithium batteries + full uncharge/charge cycles = BAD. It just shortens the life. Only do it if you feel your battery meter is screwedup. Over time the max capacity will go down so your battery will need to be recalibrated.

There is a thread somewhere here about a terminal command you can run to see max capacity and what it was at calibration.
 
skubish said:
There is a thread somewhere here about a terminal command you can run to see max capacity and what it was at calibration.
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If you have Tiger, you don't need to run the ioreg command in the Terminal any longer. You can see it in System Profiler along with the number of cycles. You will have to keep a mental note of what it was originally and what it is now. Mine has lost about 13% of its capacity in about 17 months which I don't think is too bad
 
skubish said:
There is a thread somewhere here about a terminal command you can run to see max capacity and what it was at calibration.
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I think this thread lists an alternative command for terminal (further down the thread).
 
Right now, the charger light is green, and my PB says it's fully charged at 97% (it shifts from 96-99% for no reason); I don't mean to hijack this thread, but is something wrong? I try to calibrate it every two months or so if not travelling... :confused:
 
diehldun said:
Right now, the charger light is green, and my PB says it's fully charged at 97% (it shifts from 96-99% for no reason); I don't mean to hijack this thread, but is something wrong? I try to calibrate it every two months or so if not travelling... :confused:
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I have never calibrated my battery and my PB shows some of the same things as you described. (My light usually switches over to green at 95%)

I just checked the terminal command and the system profiler and this is the result:
Capacity=4151, AbsoluteMaxCapacity=4200 with a Cycle Count of 101 (i stay plugged in most of the time).

So no, i dont think there is anything wrong with your PB.
 
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