The only thing this software does is print a colored output of triangles colored red, yellow or green. This is a visual representation of your battery status. Green means power left, yellow means power used. If there's less than 10% of energy left, the entire bar turns red.
Zsh allows putting prompts to the right side of the terminal, which can be updated every time the line changes.
By putting setopt prompt_subst to your .zshrc file, the prompts are
automatically updated with every change. Without it, they would be rendered
once and reused while the terminal is open.
Finish it off by putting RPROMPT="\$(battery)" to your .zshrc where battery
is the path to the executable. I have renamed mine from Battery to battery and
copied it to $HOME/bin which is in $PATH.