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I bought a new macbook pro, till the day I bought the battery indicator is not moving further from 96%. I wonder if there is a problem with the battery because if I unplug my power cable it is still showing 96%. My previous Mac used to show 100% or "Charged" but in OS X Lion it isn't the same, is it?

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<kbd>Option</kbd>-click the battery menulet. What is the battery condition? –  daviesgeek Sep 9 '11 at 16:45
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When i clicked, it showed me, Battery is charged. –  linguini Sep 9 '11 at 16:48
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Hold down the Option key, then click the menulet. It should give you the battery condition. –  daviesgeek Sep 9 '11 at 16:53
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@daviesgeek: I was a bit surprised, but I do have a job to do. Just don't let it happen again or you'll be in real trouble! [wags finger with comedic intensity and a sarcastically-furrowed brow] –  Philip Regan Sep 9 '11 at 18:58
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Here are the troubleshooting steps: 1. Turn Off 2. Hold down the keys: Shift+Ctrl+Alt(Option)+Power button all together for 25 Seconds. 3. Restart the system. –  linguini Sep 9 '11 at 19:08

2 Answers 2

up vote 1 down vote accepted

You probably need to recalibrate your battery. This will essentially tell the OS what the full charge is and in general make the "% remaining" more accurate. You may also need to reset the SMC

Coconut Battery is a great freeware application to give you more info on your battery health.

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Do note, that the new unibody macs with integrated batteries (the ones users don't just swap without tools) do not need any sort of calibration. The system uses adaptive charging rather than the old calibration routine. I have seen a brand new battery need a normal cycle or two to top off - and do note that often the charging circuitry is "lazy" - it sometimes will wait until you are down 10% before starting a charge. –  bmike Sep 9 '11 at 22:47

Over time, a battery will stop holding 100% of its charge. This is normal. After a good 1-2 years of constant use, I have seen this happen on all of my batteries.

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This is not true. While batteries over time do see a reduction in charge capacity, this "plateau" will not affect the OS's interpretation of what is full (100%). For example, if a new battery had a charge capacity of 5000 mAh then OS X would mark that as a full charge (100%). If it degraded over time to 3000 mAh, then the OS would mark that new value as a full charge. You can consult your System Information.app (in /Application/Utilities) for details (listed under Hardware/Power) or to see the "Full charge capacity" and the charges remaining. –  cksum Sep 9 '11 at 18:45
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I forgot to name my source, I was basically stating what two different Apple Geniuses have previously told me. While their statements directly contradict yours, it is likely that both Geniuses could be misinformed. The sad part of that is that they are misinforming users as well. –  Christian Correa Sep 9 '11 at 21:10
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You both could be right about parts of the story. The old technology did indeed stop showing 100% as a battery aged. Especially if you didn't recalibrate them - this is far less true today. It really depends on whether you are speaking in general or in reference to a specific mac. –  bmike Sep 9 '11 at 22:49
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Lithium ion/polymer batteries, as has been used by Apple for well over a decade in their portables, does not show a "memory" footprint if not discharged and charged fully (as was exhibited by nickel cadmium batteries). Moreover, while any battery will see a degradation of maximum charge capacity over time, the OS would not report this to the user. As far as the OS is concerned, it will match the full charge capacity (FC) with the current charge (CC) capacity to deliver the percentage (e.g., FC=800 / CC=799 = 99%). The OS does not know the "once maximum" battery capacity, just the current. –  cksum Sep 9 '11 at 23:20
    
@cksum — I don’t know about the OS, but the excellent coconutBattery knows the design capacity of my battery. –  Nicolas Barbulesco Nov 1 '13 at 16:52

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