Originally Posted by wingnut60
Your factory Dodge system should be just fine. The charge circuit is fused, or has a 30 amp CB or relay. One thing you will find out, is--you will never overcharge your trailer batteries with the tow vehicle--just ain't gonna happen. More than likely, you will find it has trouble doing more than just keeping up with what you might be using.
I agree. I can't imagine a 5er in tow would use more than 6 amps for the 12v systems that are left on. If the batteries were in decent condition, the amp draw from those wouldn't be more than 10 and that wouldn't last long. Certainly 30a would cover any draw while traveling.
Even if a full 14.5v made it to the batteries (which it won't with that long of run) 14+v will never hurt the batteries. Actually, 14.5v is good for them for desulfation periodically. I know in my A, my house batteries are getting 14.5v 8 hours a day while driving. They are 8 years old and still in perfect shape. I know if I was towing something and it sucked 40amps, something would be very wrong.