cpap and rvs

Can anyone provide information regarding the use of cpaps
in a camperized van.
Like how much it draws when we are not on shoreline and are
depending on rv battery to sustain the sleep.

Different machines have different requirements.
A few of the folks here have worked the camping/off-the-grid thing,
but it would help if you sign in and complete the equipment portion under User panel.
--Text works better than pictures.
Welcome to our community.