Without first calibrating a new battery, you may experience erratic battery behaviour. Battery calibration is a recommended step for all new batteries, and can even smooth out issues with older batteries as well. To calibrate your battery, follow these steps:

  1. Plug the MacBook in and charge it to 100%. It’s okay to use the laptop during this step.
  2. Keep the MacBook plugged in for a few more hours. Once the charge hits 100%, keep it plugged in for an additional two hours. You can keep using it during this step as well.
  3. Unplug, and use your MacBook until the battery completely drains. Make sure you save your work once it hits 10% or so—it will most likely go into low-power sleep without warning. If you need a quick, low-maintenance way to drain the battery, try streaming a video with the screen brightness all the way up.
  4. Wait two or three more hours for the battery to completely die. MacBooks go into a power-saving sleep when the battery gets low in an attempt to save what you were working on. We want to drain the battery as much as possible, so once the low-power sleep mode kicks in, wait another couple hours for the last of the charge to drain (longer is better).
  5. Plug the MacBook back in and let it charge uninterrupted back to 100%. It’s okay to use the laptop during this step, but if you can, try to keep the usage light.
  6. Repeat this entire process again one more time. Follow steps 1 through 5 a second time. That’s it, your battery is now calibrated!