Hey guys Will here, today I'm going to go through the process on how to replace the battery on a 2012 MacBook Air.
The batteries died on this one it won't work unless it's plugged in all the time, it also needs to be cleaned out there's a lot of dust and dirt that's built up inside, it hasn't been serviced in a long time so we'll be going through that process as well.
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Tools Required
The tools and consumables you'll need are a T5 sized Torx screwdriver, P5 pentalobe screwdriver and a can of compressed air, along with a set of rubber gloves, paper towel and windex.


Before we get started, power down the MacBook, close the display, and lay it on a soft surface top-side down.

Battery Removal
Step 1
Use a p5 pentalobe driver to remove 10 screws securing the lower case. There will be two 9 millimeter screws and eight 2.6 millimeter screws. Take note of were the longer screws came out of so you can put them back in the right places.

Step 2
Wedge your fingers between the display and the lower case and pull upward to pop the lower case off the air.

Remove the lower case and set it aside.
Cleaning
Next up is cleaning, using the compressed air can, spray off any dirt or debris that's built up inside and pay special attention to the fan assembly.

This is where a lot of dust and dirt accumulates so getting this as clean as possible is probably your main focus. A good way to clean the fan assembly is to spin it by hand and use the compress air to blow out the dust that has accumulated inside of it.
Also clean the fins on the rear cover which allow air to flow into the fan and onto the logic board. It's important you get this clean so use the compressed air to blow out any dust that's build up inside these fins.
Spray some windex on some paper towel next and wipe the inside of the rear cover, you can see the rubber stripping inside, this is what sits over the top of the batteries so make sure this is really clean before you put it back together.
Step 3
Now that we've finished cleaning inside it's time to remove the battery. Grab the clear plastic pull tab attached to the battery connector and pull it toward the front edge of the air to disconnect the battery from the logic board.
Be careful not to lift upward on the connector as you disconnect it.

Step 4
Remove the following five screws. There'll be three 6.3 millimetre t5 tort screws and two 2.4 millimetre t5 tori screws.

Before removing the battery be sure not to squeeze or touch the exposed lithium polymer cells.
Lift the battery from its edge nearest the logic board and remove it from the upper case.
New Battery Installation
Step 1
When you re-install the battery line the cable up with the connector, this makes it a lot easier to fit and once it's all the home you can then line the battery up with it's mounting holes.

Step 2
Now re-install the battery mounting screws, the three longer screws go in the top three holes and the shorter ones in the bottom holes.
When installing the new battery, if there is a thin plastic film on your replacement battery do not attempt to remove it, it is glued on and protects the battery back while it's inside the MacBook.
Step 3
Re-install the lower case using 10 screws keeping in mind where the two longer screws are situated.
Calibration
If you're installing a new battery, it's important to calibrate it after you've installed it. The calibration process is as follows.
Step 1
You start by charging it to 100% and keep charging it for at least two more hours.
Step 2
Then unplug it and use it normally to drain the battery. When you see the low battery warning, save your work, keep your laptop on until it goes to sleep due to low battery.
Step 3
Wait at least 5 hours and then charge your laptop uninterrupted to 100% and this will calibrate the battery so you get the most life out of it moving forward.
So that's all from me, if you guys enjoyed this post make sure to leave a comment.