How does one charge a dual battery vehicle?

RKW wrote:
What is the proper method of charging the batteries in a vehicle with dual batteries? Specifically my 2015 Ford SuperDuty Diesel.

My question ,why are you having to charge them ?? Reason I ask is its a 2015 ,and I suspect you are due for new batteries. Just went thru this. I jumped it twice , drove it ,and it started okay the next day, the day after no go. That was enough of that , new batteries .

The biggest signs on the Ram trucks, and my son experienced it too, was crazy stuff happening electronically , radio not working etc. There is no slow cranking with these Rams, telling you the batteries are getting bad, its just one day it won't start. Just a click.

As far as charging I would disconnect them ,and charge separately.