Function: display-battery-mode

Toggle battery status display in mode line (Display Battery mode).
With a prefix argument ARG, enable Display Battery mode if ARG is
positive, and disable it otherwise. If called from Lisp, enable
the mode if ARG is omitted or nil.

The text displayed in the mode line is controlled by
`battery-mode-line-format' and `battery-status-function'.
The mode line is be updated every `battery-update-interval'
seconds. (fn &optional ARG)

Variable: display-battery-mode

Non-nil if Display-Battery mode is enabled.
See the command `display-battery-mode' for a description of this minor mode.
Setting this variable directly does not take effect;
either customize it (see the info node `Easy Customization')
or call the function `display-battery-mode'.