Replacing the battery in your 2012-2015 Macbook Pros is not as impossible as you've been told. The battery is glued in. This is not a problem! Most MacBook batteries are easily unscrewed and replaced. I'm not sure why Apple chose to glue them in on these models.
The MacBook Pro pictured here was severely liquid damaged. The new battery brought it back to life. Neither myself, nor the customer, expect that computer to last, but he insisted on the repair.
Even the internet-bible of DIY repair, iFixit, doesn't have a guide for replacing the battery. They would love to sell you a frame/battery/keyboard/trackpad assembly for over \$500! However they have just the battery OEM for much cheaper. If you're going to do this repair, don't use a cheap knockoff or used battery. It's not worth the added uncertainty of success.
Disclaimer! I'm not responsible for your repair!
I believe my technique is suitable for anybody comfortable with laptop repair. Many people online have reported terrible consequences from using similar techniques. I think this way is as safe as this repair gets, and eliminates their mistakes. The details are very important. Don't just skim the guide if you're going to try this.
- Do not use any alcohol other than 99% IPA.
- Do not use any metal tools against the battery. Plastic only.
- Do not tear the battery connectors or casing.
- Do not use heat. This adhesive is not responsive to temperature. Many people have reported damaging components trying to use heat here.
Use only 99% Isopropyl Alcohol aka IPA
Most bottled alcohol you can by retail is not 99%. Locally the highest concentrate I've found is 70%. The other 30% is water. You don't want to dump 30% water into your electronics. The alcohol part is a safe solvent. It easily dissolves the glue that secures the battery to the case. Then it evaporates.
Part 1 Prepare the Macbook
To begin, pull the battery connector and remove the top lid. This will prevent you from spilling alcohol into the LCD, or cracking the fragile glass. Click here for the iFixit guide on removing the display. You need the proper pentalobe driver for the bottom cover, and the proper torx drier for the internal screws. Compared to many laptops, this display is cake to remove. If you find yourself severely challenged safely pulling off the screen assembly, you should just stop now and get professional help.
Place the computer on your bench at an angle. The alcohol will evaporate, but the goop of dissolved glue will not. You want any fluids to drain safely to the bottom of the case, rather than onto the keyboard, trackpad or logic board. The case makes a good drain-pan. The trackpad electronics are sheltered by a ridge that will prevent spillover.
Part 2 Remove the Battery
Part 2.1 Technique
To remove the battery, you're going to use alcohol to loosen the adhesive. You're going to use a plastic card to apply the alcohol and pry the battery out.
Do not just pour alcohol or any liquid into your computer. Don't squirt alcohol with a syringe. Don't fill a pan and dip the computer into it. Those people ruin their computers. You're going to target the adhesive with very small amounts of alcohol, directly applied.
Only use thin plastic pry tools. Metal tools can easily puncture the battery. That can be very bad.
Wet the edge of your plastic card with alcohol. Slide the card carefully under the battery cells. Let the glue penetrate into the adhesive. Repeatedly re-apply alcohol to the card and shimmy it under the battery cells. At first, the adhesive will be strong, but as the alcohol breaks it down, it will get softer and softer. It doesn't take long before you can push the card through the adhesive and separate the battery from the MacBook.
As you go, find the correct amount of force to use. As the adhesive dissolves, you want to cut into the adhesive with the plastic card. It will get easier as you apply more solvent. Do not get impatient and use too much force. You don't want to tear open the battery casing.
As you unglue each battery cell, be careful not to tear the casing or ribbons. You may want to use cards or guitar picks to prop the cells up so they don't become re-adhesed.
Part 2.2 Start from the sides
Loosen the outside battery cells first. The card will easily work it's way under the two outside battery cells. This is the easiest part, because there's a flat unobstructed surface under these cells.
Part 2.3 The inside cells
Take a good look at the surface underneath the inside cells. That metal plate, with all it's edges and ridges, hides the trackpad. So as you work, don't soak this area. Use your alcohol conservatively. A little goes a long way.
Above this space is the logic board. Below is trackpad circuitry. You don't want to interfere with either of those. The trackpad parts are recessed, making them easily avoidable by taking care. Keep your mess and force away from the logic board. That's your MacBook's brain. You're not a brain surgeon! Alcohol dissolves safely off electronics. But your tools are covered with glue residue as well. Let's not get that anywhere near circuit boards.
You need to apply alcohol to the adhesive under these cells, but it's hard to get under there with a card. These cells are fenced in on all sides. Use your card as a ramp. Place it between the battery cells, and drip a small amount of alcohol down the card into the crevice. Slide and wiggle the card around to spread the alcohol. You don't need a lot of it here. Don't over apply alcohol and let it drain onto the trackpad. You can't get too far into the sides with the card like this, but it's enough.
Continue to wet the edge of your card and work it into the bottom edge of the battery cells. Take your time here. Unlike the outside cells, this isn't going to be quick. It's tricky from this angle to work your card under the battery. You'll have to work your card past the ridge of black metal trackpad cover. It's going to get stuck there. Finesse and patience is key. Once you can get your card past that ridge, the rest of the battery is a piece of cake. Just lift it out.
Part 3 Install New Battery
Clean up any goo that's drained to the bottom of the computer case. The new MacBook battery has adhesive pre-installed. Press it into the case. The batter frame has rubber spacer nubs. If your replacement is missing these, transfer them from the old battery. They are important. Reattach the top lid and button everything up.
Part 4 Get Paid
Never do this repair for a friend for less than a whole case of beer!