Our '16 Ram 3500 Cummins (220a alternator) typically charges around 14.3 - 14.4v about 95% of the time. On occasion charge voltage will drop to 13.9v on a long trip when the batteries get topped-off really well.
This morning temps were almost zero (F) when I started our truck. Alternator voltage ramped up to 14.7v momentarily then immediately down to 12.1v (battery sag voltage after one engine start) about 4 or 5 times before it finally came on steady at 14.6v (it seemed like the voltage was exceeding some kind of threshold and was purposely being turned off, then on again for another try). In any case, it remained at 14.6v during our entire 6 hour drive on the freeway. Typically it will gradually drop (14.4v to 13.9v) as the batteries work towards a full charge. However, no voltage drop whatsoever on this trip.
After a bit of snooping online, it seems some manufacturers boost charging voltage when there's very cold ambient temps. Any chance this may be occurring with our truck?
Temperature compensation is something I desire in any charging device I use.
Regards, Don My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.
Before this thread gets run away with.. slightly higher voltage in cold is normal and the voltage sags you were seeing where the grid heaters cycling. Your truck is fine.
