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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Notebooks > MBP Weird Battery behaviour

MBP Weird Battery behaviour
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marsbt
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Mar 8, 2007, 12:23 AM
 
Hi,

I noticed some weird behaviour by my MBP's battery. I am running it without adapter to drain the battery fully and then will charge it. The discharge has been going on normally except at two points. When it was showing 14% battery remaining, I was watching news too and the monitor went to sleep. I pressed the Shift button to awaken the monitor and the remaining battery power changed to 25%. At that point I thought that I might have gotten confused reading the battery remaining earlier because of the TV. But when the battery was at 5% the low-battery warning showed up and I opened the System Profiler to see the charge remaining. When I closed the Profiler, the remaining battery level on the top right had changed to 10%.....now its gotten back to 6% slowly and decreasing.

What could be the cause of this? All I can think of is that its been 3-4weeks since I power cycled the battery. And hope this is not a serious problem. Anyone else experienced this earlier?
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Simon
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Mar 8, 2007, 01:56 AM
 
The numbers you read are being calculated on the fly according to your last battery calibration and the current power draw. If they change (especially when the power draw changes abruptly) it's not necessarily a bad sign. Continue to recalibrate your battery. The indicated battery level should be more accurate afterwards.
     
marsbt  (op)
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Mar 8, 2007, 03:52 AM
 
Thanks
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Macpilot
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Mar 10, 2007, 12:16 AM
 
Check your battery model number and serial number to make sure it is not part of the battery exchange program:

Apple - Support - Exchange & Repair Extension Programs - MacBook Pro
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pjosborne
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Mar 13, 2007, 03:35 PM
 
I thought I was the only one experiencing this - and it's been driving me nuts (MBP C2D 2.16Ghz). I too thought I was imagining things until I saw the battery icon go from red (18%) to black (29%). This weirdness always happens at or below around 30% charge. I'm also suspicious that on occassion I'm losing a lot of charge overnight. Last night I'm sure I had 30% charge when I slept the MPB and yet it read 0% when I woke it this morning at 0730 (and yes it was still asleep - though I can't vouch for the hours in between). A PMU reset has had no effect. I have literally just done an SMC reset - I'll let you know if it makes a difference (my MBP is mostly on AC as it's a desktop replacement so it may be a few days before I know for sure).

As to simon's point - I agree that time remaining changes as activities/usage change, but I've never seen an absolute percentage value go up like this on any of the other PBs I've had.

Peter
( Last edited by pjosborne; Mar 13, 2007 at 03:43 PM. )
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Simon
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Mar 13, 2007, 05:00 PM
 
You're absolutely right, the percentage value shouldn't suddenly increase by so much.

Any bulging of the battery? Have you tried to get Apple to send you a replacement?
     
pjosborne
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Mar 15, 2007, 02:58 PM
 
SMC reset had no effect. I've talked with Applecare and they agree it's either a logic board or battery issue. They're sending me a new battery. Hope this solves it because apparently the turnaround in the UK for a new logic board is currently running to two weeks!
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pjosborne
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Mar 20, 2007, 02:53 AM
 
Got a new battery yesterday and so far I haven't seen any of the weird behavior I was experiencing. So maybe it was a flaky battery after all.
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