Cold weather and battery performance, AGM batteries

Have the batteries tested, individually. If one is bad, replace ALL of them at the same time.

 

get yourself one of those USB phone chargers that plugs into the power outlet and has a digital voltage display and start watching the alternator voltage while the engine is running and the resting battery voltage while it’s off. They’re like $15 on Amazon.

You could have a charging system issue, tired batteries, or a draw somewhere that needs fixed. AGM doesn’t typically cause any problems even if the vehicle didn’t originally come with them. (Switching back to flooded batteries on a vehicle that originally came with AGM I’ve been told is a no-no). On a practically new truck I would be a little surprised they’d be bad already unless something else was going on.