Help with charging system.
 

Hey, need a little help. My charging system is putting out a constant 16V. I replaced both batteries today with no luck. After 30 seconds the voltage gauge went from 12-13 to 16 again.

Any other thoughts? Voltage regulator? Don't want to burn up my new batteries.

Probably voltage regulator but I would check the voltage at the batteries with a good volt meter to make sure the gauge is reading correctly.

Check the voltage at the passenger side battery and drivers side battery. It sounds as if your + battery cable that connects your passenger battery to the drivers battery is bad. The ECM senses the voltage on the drivers side battery and adjust the alternator to charge accordingly. If the cable has an issue you will get a voltage drop, hence the overcharging.

Ok, update.

I let the truck warm up and checked both batteries with my fluke. 15V on each. Not sure why, but right when it started it read 13V for about a minute then cycled between 15 and 13 for a few seconds till it warmed up then steady at 15V.

Thoughts?

All the terminals, ground points, and where the cables bolt to the terminals are all clean, yes?

Just looked and all the terminals look good. No buildup etc.

What's next? Any issues of me driving the truck like this?

Sounds about right for charging voltage. The fluctuation was probably the grid heater kicking in and dragging down the alternator briefly.

Sounds about right for me too. When it's cold, my truck charges at a higher voltage. Dodges have always done it.

So is 15V normal when the truck is warmed up? Should I see it below or near 14v? Minnesota weather here. 10's for lows and 30 for a high.

14.5 is the norm.

I had mine checked, and it'll hit 15 then drop to 14.5 after the grid heater relay opens.