Battery Lost 3% Overnight After Power It Off

Question

I have a MacBook Air that was bought brand new in August 2013. Couple months ago, I noticed that the battery lost 3% of charge each day after I powered it off. I powered it off at the end of the day around 6pm and the next morning when I powered it up again at ~9am, I found that the battery lost 3% of charge. I went to the Gensis bar to have it check out, the tech there found no problem after running the test and they suggested me to re-calibrate the battery by draining the battery all the way to 0% and then fully charged it to 100%. I tried it couple times but it is of no help.
Any idea how to fix it or diagnosis the problem?
Thanks,
Ken

Answer 1

dagored
At this rate it will have about 60 cycles in a year. When does it get near replacement time for the battery?
Cycles are rather meaningless other than in the case of old age degradation of the battery which is utterly 100% unavoidable.
Concentrate on use/abuse of the battery,  ... counting cycles serves very little purpose.
If you take care of the former, the later becomes irrelevant and ultimately unavoidable.
https://discussions.apple.com/docs/DOC-6342
Proper understanding of a battery charge cycle
A charge cycle means using all of the battery’s power, whether that is at once, or over several shorter battery discharges and recharges.
Two examples for clarification:
As a first example, where one fully charged battery is discharged down to 10%, then fully recharged, then using 10% of that full charge, this counts as 1 cycle since the total of both discharges is 100% of a full charge of use.
In the second example, where one fully charged battery is discharged down to 40%, then fully recharged, then using 40% of that full charge, this also counts as 1 cycle since the total of both discharges is 100% of a full charge of use.
While both examples are that of a single charge cycle, the first example is more aggressive against the lithium battery chemistry than is the second example. In short, collective overall gentle shallow or mid-range draining of your lithium battery is a better use condition than is the first example of deep-draining of the battery.  While both are quantitatively identical as a single charging cycle, they are wholly different qualitatively on the battery chemistry, which is directly related to its ultimate longevity and health.
In short, it is the near and mid-term life of the battery as relates to its proper care (or lack thereof) that is to be looked after.
Priorities in order of decreasing importance for battery care are:
1. Avoiding deep discharges of the battery.
2. Avoiding having your battery constantly on charge or on charge and in sleep mode.
3. When playing graphics intense games, use your notebook plugged in when possible.
4. Reduction of battery cycles by plugging into power when on the go, or when accessible.
A person who has, for example, 300 charge cycles on their battery and is recharging at say 40% remaining of a 100% charge has a better battery condition state than, say, another person who has 300 charge cycles on their battery and is recharging at say 10-15% remaining on a 100% charge. DoD (depth of discharge) is vitally important on the wear and tear on your Macbook’s battery, much more so than is the counting of charge cycles. There is no set “mile” or wear from a charge cycle in specific. Frequent high depth of discharge rates (draining the battery very low) on a Lithium battery will greatly hasten the lowering of maximum battery capacity.
Understand that a charge cycle is a general parameter of use, but is not directly related to the short-term or mid-term abuse of the battery, which can rapidly hasten a shorter lifespan, regardless of what the actual cycle count on the battery indicates.
Proper considerations for near-term care of the battery is of utmost importance. Abuse of the battery is entirely avoidable, long-term eventual old age deterioration of the battery is entirely unavoidable.
Apples SMC and software mitigates MUCH potential for battery misuse /abuse, ....however it is still readily possible to abuse the battery.