Battery Capacity Question

[teerexx52]

I have a week old 11.6" MacBook Air. The battery has 3 cycles. However, using Coconut battery the battery capacity is showing 96% fully charged. Would that be unusual after 3 cycles? Thanks

 

[spinnerlys]

Have you calibrated the battery yet?

This should answer most, if not all, of your battery questions: Apple Notebook Battery FAQ

Apple on notebook batteries

Apple Portable: Calibrating your computer's battery for best performance

Laptop Battery Guide

 

[neteng101]

All Mac batteries drain down to 95% before the charging process occurs again. The question is really what is the battery capacity reported, between current and designed. Mine's at 101% for now.

 

[teerexx52]

No, I haven't calibrated it yet. Would that be the cause of the reading?

 

[spinnerlys]

All Mac batteries drain down to 95% before the charging process occurs again. The question is really what is the battery capacity reported, between current and designed. Mine's at 101% for now.

I think you somehow confuse two things:

One is the charge (95%, mentioned by you), the other is the battery health (97%, mentioned by the OP).

For example: The 2009 17" MBP has a battery capacity of 13,000mAh, if the charge is at 95%, there are still 12,350mAh of charge left.
If the battery health is reported as 97%, the maximum battery capacity is reduced to 12,610mAh, thus 95% charge of that capacity would be 11,980mAh.

It is true, the battery not always charges to 100% charge, but it normally does over time.

This should answer most, if not all, of your battery questions: Apple Notebook Battery FAQ

No, I haven't calibrated it yet. Would that be the cause of the reading?

Seems that way.

The battery has an internal microprocessor that provides an estimate of the amount of energy in the battery as it charges and discharges. The battery needs to be recalibrated from time to time to keep the onscreen battery time and percent display accurate and to keep the battery operating at maximum efficiency. You should perform this procedure when you first use your computer and then every few months after that. If you normally leave your Apple portable computer connected to AC power and very rarely use it on battery power you may want to perform this process once a month. The website http://www.apple.com/batteries has more helpful information regarding batteries and offers an iCal calendar to remind you to calibrate your battery.

from Apple Portable: Calibrating your computer's battery for best performance

 

[teerexx52]

I think you somehow confuse two things:

One is the charge (95%, mentioned by you), the other is the battery health (97%, mentioned by the OP).

For example: The 2009 17" MBP has a battery capacity of 13,000mAh, if the charge is at 95%, there are still 12,350mAh of charge left.
If the battery health is reported as 97%, the maximum battery capacity is reduced to 12,610mAh, thus 95% charge of that capacity would be 11,980mAh.

It is true, the battery not always charges to 100% charge, but it normally does over time.

​

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Thanks. Mine shows design capacity 4680, current capacity 4501 It says its 100% charged but only 96% of capacity. Unless its because it has not been calibrated isn't that much loss over 3 load cycles unusual. I mean 4% for 3 load cycles. If that were to continue at that rate? I'll calibrate it tomorrow

 

[spinnerlys]

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Thanks. Mine shows design capacity 4680, current capacity 4501 It says its 100% charged but only 96% of capacity. Unless its because it has not been calibrated isn't that much loss over 3 load cycles unusual. I mean 4% for 3 load cycles. If that were to continue at that rate?

The battery has to be "run in". My MBP's battery fell from 99% to 91% in less than 30 cycles, but over time and due to proper calibration, the battery health is now reported as 99%.

Maybe you have noticed this, but this topic comes up every day, almost anyway, thus you should find plenty of threads about this.