How do you suppose the truck’s main batteries ever get charged?
I’m gonna say the alternator does it. And if you connect the camper batteries in parallel, they get charged just the same.
The regulator drops the voltage as the load decreases, which happens as the batteries get charged up. When you connect the camper batteries, and they’re low, it puts more load on the alternator EXACTLY like when the main starting batteries are low.
The alternator just sees the whole bank of however many batteries are connected as one big battery.
