Coconut Battery says new Air has 99% capacity...why not 100%?

not all batteries are equal. CB uses a fixed level to calculate % health. Just that not all batteries have the exact same capacity right off the bat to the resulting % will be off

FWIW, my brand new 2012 mbp had a reading of 93% with 0 cycle fully charged

It has since stayed at that amt since I have had it since June

 

Don't worry about it- 1% wouldn't be noticeable if it was a battery issue, which it probably isn't.

 

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.

The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it.

Apple Notebook Battery FAQ​

 

I don't have a need for it yet, but thanks for putting that FAQ together!