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Jobsian

macrumors 6502a
Original poster
Jul 30, 2009
853
98
I'm wondering about the variability here as it seems quite high from what I'm reading. From this site it seems the design capacity of these batteries is

4680 mAh for the 11" models
and
6700 mAh for the 13" models


Post which 2012 MBA you have and its capacity from the System Report (click About This Mac in the top left of the screen then 'more info'). Mine:

11" - Full Charge Capacity (mAh): 4592


_
 
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Jobsian

macrumors 6502a
Original poster
Jul 30, 2009
853
98
Does anyone know whether or not this is a fixed number early on into the cycles, as we're already seeing some variability?
 

Intell

macrumors P6
Jan 24, 2010
18,955
509
Inside
The full charge capacity will go up and down throughout the machine's life. This is normal. It can range from 85% to 110% and still be normal.
 

Beau10

macrumors 65816
Apr 6, 2008
1,309
665
US based digital nomad
My 11" has fluctuated a bit from 4732-4799 (currently 4786 on 3 cycles). Haven't bothered to do a full calibration yet, just got the machine yesterday. Will let it go thru a few more cycles first.
 

dmk1974

macrumors 68020
Sep 16, 2008
2,389
464
2012 11" base Air
5 charge cycles
Full Charge Capacity (mAh): 4516

That kinds sucks, right?
 

GGJstudios

macrumors Westmere
May 16, 2008
44,545
943
Haven't bothered to do a full calibration yet, just got the machine yesterday. Will let it go thru a few more cycles first.
The built-in batteries in the newer Mac unibody notebooks come pre-calibrated and do not require regular calibration like the removable batteries.

This should answer most, if not all, of your battery questions:

First Mac here...how do I check?

Cheers.
iStat Pro will give you battery information, as well as temperatures, fan speeds, uptime, etc. It's very handy.... and free!
 
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JDrive

macrumors member
Jun 3, 2010
38
3
First Mac here...how do I check?

Cheers.

From the "About This Mac" window click "More Info...". Then click "System Report..." and "Full Charge Capacity (mAh)" is listed under "Power".

My 13" currently lists 6566.
 

Beau10

macrumors 65816
Apr 6, 2008
1,309
665
US based digital nomad
The built-in batteries in the newer Mac unibody notebooks come pre-calibrated and do not require regular calibration like the removable batteries.

This should answer most, if not all, of your battery questions:

While the battery may be now calibrated from the factory (and that's interesting, thank you), that they do not benefit from further calibration is certainly wrong - they must be speaking to a consumerist POV where sure, it isn't quite necessary "do not require". I experienced this in my last MBA and would routinely see my battery change by up to 5% after letting it go for a couple months.

All lithium ion batteries suffer drift in their readings, and clearly that's what I was getting at - getting an accurate reading of the capacity. That's the point of this thread, no?
 
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GGJstudios

macrumors Westmere
May 16, 2008
44,545
943
While the battery may be now calibrated from the factory (and that's interesting, thank you), that they do not benefit from further calibration is certainly wrong .
Tell that to Apple. Generic information about lithium ion batteries don't necessarily apply to the specific implementation in Apple's lithium polymer battery technology. I would trust the manufacturer, who is financially responsible to replace defective batteries and who is responsible if the information they provide is flawed. They know more about their own technology than any generic site.

While calibrating the battery in unibodies won't harm it, it's not necessary.
 

Beau10

macrumors 65816
Apr 6, 2008
1,309
665
US based digital nomad
Tell that to Apple. Generic information about lithium ion batteries don't necessarily apply to the specific implementation in Apple's lithium polymer battery technology. I would trust the manufacturer, who is financially responsible to replace defective batteries and who is responsible if the information they provide is flawed. They know more about their own technology than any generic site.

Tell what to Apple? The point of this thread and "replacing defective batteries" are orthogonal to each other.

Apple may have somehow reduced the tendency to drift, but there's no way they can fix what is inherent in the technology.
 

Jobsian

macrumors 6502a
Original poster
Jul 30, 2009
853
98
I'm 4 cycles in and from my opening post when I was getting 4592 mAh, it has gone down to

Full Charge Capacity (mAh): 4576

I wonder if this is normal? Will be interesting to see where it goes from here, I'm hoping up!
 

GGJstudios

macrumors Westmere
May 16, 2008
44,545
943
I wonder if this is normal? Will be interesting to see where it goes from here, I'm hoping up!
It is perfectly normal if your battery health (maximum capacity) is more or less than 100%, even when brand new, or if it fluctuates up or down over time. For further details, read the CHECKING STATUS AND HEALTH section of the following link.

This should answer most, if not all, of your battery questions:
 

Jobsian

macrumors 6502a
Original poster
Jul 30, 2009
853
98
It is perfectly normal if your battery health (maximum capacity) is more or less than 100%, even when brand new, or if it fluctuates up or down over time. For further details, read the CHECKING STATUS AND HEALTH section of the following link.

This should answer most, if not all, of your battery questions:
Thanks, will do.

Health at 97%
 

Jobsian

macrumors 6502a
Original poster
Jul 30, 2009
853
98
Did a recalibration. Guess what I got?

11" Full Charge Capacity (mAh): 4600

Right on the money!
 

Hichisky

macrumors member
Nov 5, 2010
36
0
On my 11" I am getting:
Full Charge Capacity (mAh): 4454

Which I think is the lowest so far. I might try the calibration thing, though supposedly you don't need too.
 

GGJstudios

macrumors Westmere
May 16, 2008
44,545
943
On my 11" I am getting:
Full Charge Capacity (mAh): 4454

Which I think is the lowest so far. I might try the calibration thing, though supposedly you don't need too.
You definitely don't need to calibrate. Remember, calibration does not affect or change your battery health in any way. It only makes your readings more accurate.
 

Hichisky

macrumors member
Nov 5, 2010
36
0
You definitely don't need to calibrate. Remember, calibration does not affect or change your battery health in any way. It only makes your readings more accurate.

Yeah, I know, I was speaking in terms of getting a more accurate reading. But I figure I won't bother. I feel the battery life is pretty decent anyway. Thanks. :)
 
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