We have Messenger 3.0 installed and working great with several users on
mobile devices, both Android and iOS.
I have it installed on my Samsung Note 4 running Android 5.0.1 and is is the
single biggest battery user on the device.

I now Log out to save on battery, and log in as and when I need to send or
check messages.

Does anyone else have any info on battery use on other Android or iOS

Mark Behrens