That is normal operation. When it is that cold the batteries supply all of the power to the truck for the first two minutes of idling (not to exceed 150 seconds) or until you get above 20mph. It's Dodge's way of protecting the electrical system.
Good luck with the redtops. They have never lasted for me in three different vehicles.
Retired Navy Chief - Vanilla 04 2500 QCSB, 4x4, 48RE w/MagHytec DD, Smarty Jr, HOG 4" Exh, Modded Air Box, Isspro Gauges, Quadzilla RPG w/fuel pressure, DynaTrac front, Coolant By-Pass Filter - B&W Turnoverball w/Companion 5vr hitch