If your Mac battery runs out of charge quickly
If the battery in your Mac laptop runs out of charge more quickly than you expected, try any of the following:
Check your battery’s condition. The battery’s ability to hold a charge may be less than when it was new. See Check the condition of your Mac laptop’s battery.
Change your settings. For example, dim the display, turn off Bluetooth and Wi-Fi, and set the display to turn off after a period of inactivity. See Save energy on your Mac.
Turn on Low Power Mode. See Change Battery settings on a Mac laptop.
Quit apps that you aren’t using. Even an app you aren’t using may be working in the background and consuming energy.
Disconnect any accessories that you aren’t using, such as external hard drives.
Keep your software up to date. See the Apple Support article Update macOS on Mac.