How hard it is to replace the battery depends on the model of MacBook you have.
If your MacBook is one of the early models that has a user removable battery, replacing it is just a matter of popping the old one out and replacing it with the new battery. However, if you have a model without a removable battery, you will need to open your MacBook’s case. And for that, you will need a guide.
The job essentially consists of these steps:
- Power down the MacBook
- Undo the screws holding down the back cover
- Unplug the battery from the motherboard
- Remove the screws holding down the battery
- Lift the battery out of the MacBook
- Fit new battery
- Screw the battery down
- Refit the connector
- Fit the back cover
- Test the MacBook
A Note on Safety
Lithium-ion batteries like the one inside your MacBook can literally explode. This is something you really need to bear in mind when you are considering a repair job like replacing the battery.