On Fri, 31 Jan 2014 07:01:29 -0800, dave wrote:

Turn off GPS.
Turn off mobile data
Voice and Text are not on Mobile Data.

Luckily, I don't even have mobile data.
I do use GPS navigation all the time in the car though.
That's the whole point!

If the phone can't keep up with the GPS while
on the car charger, um, what good is GPS?

Note: I have gone on long trips (4 hours), and
if the battery is charged (say, 50%) it stays
at about that level; but if the battery is low
(say 20%), then the battery steadily depletes.

That's the enigma I'm trying to understand.