My Packtalk Bold/ Garmin 595 combo also does this,not all the time but a lot of the time. Todays ride it was fine for the first half hour or so then suddenly started doing it for the remainder of the ride. I’ve just gotten used to it as it’s always done it.
Strangely my packtalk is half of a twin pack bought with a friend and his is fine also his battery lasts all day were as mine doesn’t.