MacBook – Does Macbook Air (mid 2013) bypass battery after it’s charged

Read what Apple has to say about notebook batteries:

1. Apple’s Batteries Page
2. Apple’s Notebook Batteries Page

EDIT for the lazy(es) who don’t want to read the links:

1. lithium-ion batteries need to be fully discharged and recharged at least once a month. Go ahead and create an iCal reminder…
2. Leaving it plugged won’t affect it, as long as you remember to do (1) every 30 days.
3. If you have to “store” and put your battery away for more than six months, you should definitely store the battery with a 50% charge. Reasons are listed in the corresponding link.
4. Pay attention to temperatures, they can damage and severely hamper battery operation.

I hope this makes everybody happy.

Now… as a final note: the new unibody stuff coming from Apple doesn’t have removable batteries, however, the battery design is the same… those are lithium-ion batteries, no matter how fancy they make it look. Macbooks do not have a nuclear core in there, so the same rules apply, except that… well, you can’t remove it for storage, so more than ever, remember the 30 day rule.

Don't worry. It will use the wall outlet if that offers enough power which it should using the original AC adaptor.

What if the power is going from 100% down to 99.6%, then back up to 100% constantly?

That was until about a decade ago or so. Modern laptops even don't charge your battery if it is eg. at 98% for reducing unnecessary cycles. Don't bother about your battery in your computer.

If you want to care for your battery, just remember every cycle shortens battery life, no matter if 10 minutes on battery or completely emptied it. The battery has also some natural aging, so it will die after some years even if you never touch it.