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.
Service Recommended: The battery is performing normally, but its ability to hold a charge is less than when it was new. You may want to consider replacing the battery.
Note: The battery may also not be functioning normally, and you may or may not notice a change in its behaviour 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.