Battery Indicator Inaccurate

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Level 1

4 points

Battery Indicator Inaccurate

Hello,

I think since the 10.9.2 upgrade, my battery percentage is off (higher) by 3% - 5%. I am basing this on calculating the percentage of: charge remaning / full charge capacity in the SYSTEM INFORMATION utility. I checked this on an older Macbook and charge remaning / full charge capacity percentage is spot on with the percentage showing up in in the battery percentage indicator.

Thanks,

Manish

MacBook Pro (Retina, 13-inch, Late 2013), OS X Mavericks (10.9), 8GB RAM, 256GB SSD

Posted on Mar 22, 2014 7:22 AM

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Answer 1

OGELTHORPE

Level 9

57,305 points

Mar 22, 2014 7:34 AM in response to Umarwadia

Umarwadia wrote:

Hello,

I think since the 10.9.2 upgrade, my battery percentage is off (higher) by 3% - 5%. I am basing this on calculating the percentage of: charge remaning / full charge capacity in the SYSTEM INFORMATION utility.

When the battery of a MBP has been fully charged to 100%, even if the power adapter is attached during use, the OSX will stop charging the battery and the charge level will fall. When the level drops below 95% of the possible maximum charge, then the OSX will engage the charging circuitry and charge the MBP to 100%. This may account for the discrepancy.

Ciao.

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Answer 2

Umarwadia Author

Level 1

4 points

Mar 22, 2014 8:16 AM in response to OGELTHORPE

Hi,

I've never noticed this discprepancy before and it does not occur on my older Macbook, i.e. charge remaining (mAh) divided by full charge (mAh) always equals the battery percentage in the status bar. In fact, Coconut battery shows the correct percentage per the math above. It's just the battery % icon shows a remaining charge 3% - 5% higher. I am wondering if others are seeing the same thing or can confirm or deny my observation. When I called up the Apple Suppory folks, they were clueless, they were hung up on full charge capacity declining over time vs. design capacity (agree) but this has nothing to do with the design capacity, it should be simple math for the % remaining.

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Answer 3

OGELTHORPE

Level 9

57,305 points

Mar 22, 2014 10:05 AM in response to Umarwadia

Umarwadia wrote:

It's just the battery % icon shows a remaining charge 3% - 5% higher.

Is this higher percentage displayed on the menu bar, but System Information (Charge Remaining ÷ Full charge Capacity) and CoconutBattery both show the same but different percentage?

This is from my MBP:

They all are consistent with each other.

Ciao.

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Answer 4

Umarwadia Author

Level 1

4 points

Mar 22, 2014 1:01 PM in response to Umarwadia

Hi,

Thanks for the screenshots. My readings are inconsistent between the battery percentage displayed on the menu bar (higher) vs. the battery percentage calculated by Coconut Battery and the SYSTEM INFORMATION data on the MBP itself. See screenshot below.

You can see the icon showing 96% but Coconut Battery and the SYSTEM INFORMATION utility both show 91% (a 5% differential). I think this crept in with OSX 10.9.2 but can't be sure.

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Answer 5

OGELTHORPE

Level 9

57,305 points

Mar 22, 2014 1:12 PM in response to Umarwadia

Try a SMC reset:

http://support.apple.com/kb/ht3964

Ciao.

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Answer 6

Umarwadia Author

Level 1

4 points

Mar 23, 2014 7:49 AM in response to OGELTHORPE

Tried SMC reset twice but still the same issue.

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Answer 7

OGELTHORPE

Level 9

57,305 points

Mar 23, 2014 7:58 AM in response to Umarwadia

The only possible remedy that I can think of at this point is a reinstall of the OSX.

Ciao.

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Answer 8

Umarwadia Author

Level 1

4 points

Mar 23, 2014 1:37 PM in response to OGELTHORPE

Hi,

Did the OSX reinstall and the issue still persists. I am wondering if people have a similar issue with OSX 10.9.2? I can't quite make out your OSX version from your screeshots.

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Answer 9

Mar 23, 2014 1:40 PM in response to Umarwadia

its only an estimate, stop worrying about it.

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Answer 10

OGELTHORPE

Level 9

57,305 points

Mar 23, 2014 4:09 PM in response to Umarwadia

I am using Lion (10.7.5). I have no reason to believe that this is an issue with Mavericks. You are the first to report this that I am aware of. I made a quick check of past posts regarding incorrect battery data being displayed, I have only found one but it appears it was an issue with a near dead battery.

If you wish to pursue this further, then an Apple store genius bar appointment should be made. They will perform a free evaluation. If you do that, please let me know the results. I would be interested.

Ciao.

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Answer 11

tinsky12

Level 1

0 points

Jul 11, 2014 5:57 AM in response to Umarwadia

Hi, I was wondering if you already figured out what occurred to your rMBP? I'm in the same situation as yours, did both the SMC and NVRAM reset as well as clean installing Mavericks, but the problem still persists!!! This is frustrating!

Late 2013 13" rMBP

8 gigs ram, 256ssd, i5 2.4ghz

OSX 10.9.4

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Answer 12

René A.

Level 1

0 points

Aug 10, 2014 1:09 PM in response to tinsky12

I'm having the same issue with my new Macbook Pro (Mid 2014).

My MBP shows 100 % battery charge , but Coconutbattery just 95%. After this point (MagSafe's led switches to green when status bar shows 100 %) coconut still thinks that the MBP is charging and shows the 100 % after nearly 2 hours. After unplugging my MBP , the status bar indicator stays about 10 Minutes at 100 % while Coconut displays a normal discharge (when coconut shows exactly 95 % charge the status bar starts decreasing, too)

I've noticed the 5 % offset after switching from bootcamp to Mac the first time (Windows forced Sleep Mode at 5 % charge -> after rebooting to Macbook : 5 % offset)

Is there already a solution for this problem? (tried SMC and PRAM reset already)

(Sorry for my bad english)

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Answer 13

Mar 15, 2015 1:23 AM in response to Umarwadia

Hi,

I have exactly the same issue with a Macbook Pro Retina 13'' (mid-2014). It had Mavericks installed and upgraded to Yosemite just after purchase.

The system's battery % indicator is consistently about 3-5% higher that the "real" percentage. Understanding by real percentage the division between current charge in mAh and maximum charge in mAh, that is what apps like Coconut battery show.

Right now system shows 96% while cononut shows 91%.

I have tried calibration, SMC reset, NVRAM reset, as explained above. Nothing helped.

I have no idea what is happening but it seems clear that the system percentage is not the result of dividing current and max charge capacity. Maybe MacOSx applies some correction? (no linear division), but then, why only few users see this problem?

Another 'issue' that I am not sure if it is related or not: in my macbook is almost brand new, the maximum charge is deteriorating faster than normal, I think. When I bought it, battery was 3 month old from factory. Max capacity was 6350 mAh (100% of designed 6330mAh), but normally when brand new batteries have capacity higher than 6400.

After only 3 cycles capacity has dropped to 6200 mAh (98%).

Daniel

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