Check the condition of your Mac computer’s battery
You can check whether the battery in your portable Mac is functioning normally and approximately how much charge it can hold.
To view your battery’s condition, press and hold the Option key and click the battery icon 
in the menu bar.
You may see any of the following conditions:
Normal: The battery is functioning normally.
Replace Soon: The battery is functioning normally but holds less charge than it did when it was new.
Replace Now: The battery is functioning normally but holds significantly less charge than it did when it was new. You can continue to use the battery until you replace it without harming your computer.
Service Battery: The battery isn’t functioning normally, and you may or may not notice a change in its behavior or the amount of charge it holds. Take your computer in for service. You can continue to use your battery before it’s checked without harming your computer.