Install wmbattery by entering the following commands in the terminal:
sudo apt update sudo apt install wmbattery
Description:
display laptop battery info, dockable in WindowMaker
wmbattery displays the status of your laptop's battery in a small icon. This includes if it is plugged in, if the battery is charging, how many minutes of battery life remain, and battery status (high - green, low - yellow, or critical - red). . There's nothing in the program that makes it require WindowMaker, except maybe the look. It can be docked in WindowMaker or AfterStep's dock. . wmbattery supports multi-battery machines, and can estimate how long it will take the battery to finish charging or discharging.
Homepage: http://www.dockapps.net/wmbattery
Version: 2.51-1
Section: universe/x11