MacBook Air 13 inch, mid 2012: 21 charge cycles, battery capacity 6315 mAh (94%). A bit on the low side, I would say. Wonder how, after 1000 hcarge cycles, it will still be above 80%.
OS X Mountain Lion (10.8.2)
It will go up and down. What is more important is the average and trend. A single percentage reading does not tell the whole story. Here's mine.
| Date | bq20z451 1 |
| 2012-09-10 | 6377 |
| 2012-09-11 | 6389 |
| 2012-09-13 | 6391 |
| 2012-09-14 | 6399 |
| 2012-09-15 | 6444 |
| 2012-09-16 | 6448 |
| 2012-09-17 | 6428 |
| 2012-09-18 | 6423 |
| 2012-09-23 | 6420 |
| 2012-09-24 | 6398 |
| 2012-09-25 | 6449 |
| 2012-09-26 | 6447 |
| 2012-09-27 | 6401 |
| 2012-09-28 | 6400 |
| 2012-09-29 | 6400 |
| 2012-09-30 | 6400 |
| 2012-10-05 | 6358 |
| 2012-10-06 | 6370 |
| 2012-10-07 | 6420 |
| 2012-10-08 | 6420 |
| 2012-10-09 | 6364 |
| 2012-10-10 | 6316 |
| 2012-10-11 | 6322 |
| 2012-10-12 | 6357 |
| 2012-10-13 | 6346 |
| 2012-10-14 | 6352 |
| 2012-10-15 | 6354 |
| 2012-10-16 | 6333 |
| 2012-10-17 | 6337 |
| 2012-10-18 | 6346 |
| 2012-10-19 | 6327 |
| 2012-10-20 | 6326 |
| 2012-10-21 | 6329 |
| 2012-10-22 | 6364 |
| 2012-10-23 | 6373 |
| 2012-10-24 | 6361 |
| 2012-10-25 | 6353 |
| 2012-10-29 | 6312 |
| 2012-10-30 | 6310 |
| 2012-10-31 | 6320 |
| 2012-11-01 | 6361 |
| 2012-11-02 | 6358 |
| 2012-11-03 | 6356 |
| 2012-11-04 | 6325 |
It's one of those things where you need to wait and see. It's impossible to try and forecast the expected charge capacity of a battery in 1,000 cycles when you're on cycle X. One of the remote users I support recently broke 1,000 charge cycles on his Mid 2010 MacBook Pro. The battery was holding steady at 83% of the original charge capacity. Considering the beating that machine has taken in the field and countless hours of research and documentation it's been put through the owner always sings the praise of that machine.
Battery is declining and declining: at 93% after 24 cycles. I give it 180-250 cycles before it drops below 80%. Had three different batteries in my previous Macbook Pro and monitored their decay over 4 years. The last one simply lost it at 170 cycles for no good reason. This is the worst so far. My experience: once it starts decaying, it accelerates exponentially. So far I never had a properly lasting battery in any of my macbooks...and I am very particular when it comes to maintenance: mb is never plugged in for extended periods and used daily. Wonder whether it got heat damage during delivery in early August.
Also, I wonder whether it holds its charger properly: it loses ca. 15% per day when in sleep mode with power nappe on.
Date,"bq20z451 1"
2012-09-10,6377.0
2012-09-11,6389.0
2012-09-13,6391.0
2012-09-14,6399.0
2012-09-15,6444.0
2012-09-16,6448.0
2012-09-17,6428.0
2012-09-18,6423.0
2012-09-23,6420.0
2012-09-24,6398.0
2012-09-25,6449.0
2012-09-26,6447.0
2012-09-27,6401.0
2012-09-28,6400.0
2012-09-29,6400.0
2012-09-30,6400.0
2012-10-05,6358.0
2012-10-06,6370.0
2012-10-07,6420.0
2012-10-08,6420.0
2012-10-09,6364.0
2012-10-10,6316.0
2012-10-11,6322.0
2012-10-12,6357.0
2012-10-13,6346.0
2012-10-14,6352.0
2012-10-15,6354.0
2012-10-16,6333.0
2012-10-17,6337.0
2012-10-18,6346.0
2012-10-19,6327.0
2012-10-20,6326.0
2012-10-21,6329.0
2012-10-22,6364.0
2012-10-23,6373.0
2012-10-24,6361.0
2012-10-25,6353.0
2012-10-29,6312.0
2012-10-30,6310.0
2012-10-31,6320.0
2012-11-01,6361.0
2012-11-02,6358.0
2012-11-03,6356.0
2012-11-04,6325.0
2012-11-05,6327.0
2012-11-06,6285.0
2012-11-07,6284.0
2012-11-08,6311.0
2012-11-09,6307.0
2012-11-10,6291.0
2012-11-11,6312.0
2012-11-12,6240.0
So then bring it in for service if you feel the battery is defective. I'm at 92% of original capacity at 28 cycles and I still get the same run time I did when I first received the computer. If you're not happy with the battery health degradation bring the machine in to request a replacement battery.
Jason,
Thanks for the info on your battery. Apple will not replace a battery before it has dropped below 80%. I am not worried about the present performance but its decline in the near to intermediate future and therefore a possible unreability. My old Macbook Prohas a battery with 180 cycles on it and it is toast. It started like this and in the end, it just went from 80% to zero.
Interestingly, I have seen abattery with 19 cycles and 6652 mAh, so close to design capacity.
Jürgen Kraus wrote:
Jason,
Thanks for the info on your battery. Apple will not replace a battery before it has dropped below 80%.
Apple will absolutely replace a battery before it has dropped to below 80%. Yes the posted 300/80% or 1000/80% is typically enforced but I've had on four separate occasions batteries replaced that had not dropped below 80% but suffered significantly reduced performance.
I'm not saying that they will always replace the battery under any circumstance but there's definitely not a "hard and fast" rule from my experience (on both sides of the Genius Bar).
While it is not a pressing issue yet, we should just keep this tread open and monitor battery performance over time, wondering how it works out in the next few months. One thing I notice: in my old Mabook Pro, battery charged fast until 95%, then slowly until 100%. If you plugged it in at let say 96 % full, it would naturally would not accept charge. This was explained on the Apple support site.
This one is different: even if I plug it in at 98%, it would charge rapidly to 100% (within 10 mins) and the green light comes on at below 100%. In my case I noticed I was 200 mAh below full capacity of 6500 mAh when it turned from red to green. All this may be normal, but I don't know whether it is - Apple support line didn't know either. If this rapid charge behaviour was not normal, this would explain the relatively fast battery decay.
I use Battery monitor by Marcel Bresink...$5 well spent.
OK, the 98% thing appears to be normal.
I was also trying to find a chart or some kind of guide about the expected decline levels or what should be considered "normal." Right now, my battery seems to be doing well compared to most, from what I've seen here.
My MBA is 28 Months old, is showing 170 battery loadcycles, and is at 93% or 6248 mAh. I can usually use wifi and slightly lower screen brightness for a good five hours at least, although I've never really timed it.
Plus I was kind of worried because my laptop has been left in the car a couple of times, and since I'm from sunny S. California, temperatures definitely reached over 100F - I've heard of heat damage, but what kind of circumstances are we talking about?
battery capacity drop Macbook Air
