Question regarding dual batteries and alternators charging RV batteries

[Cookninaz]

I have a 2024 Ram 3500 with Cummins diesel and dual batteries with dual 220 amp alternatives. I'm upgrading to a 280AH Litime lithium battery from a 88AH lead acid battery. Will the power going through the 7 pin connector be enough to charge the new battery while driving (3 hour minimum) or would I benefit from a dc to dc charger?
Thanks!

 

[Cookninaz]

I should have mentioned that I'm upgrading the battery in my 35 foot 5th wheel.

 

[Thewookie]

I should have mentioned that I'm upgrading the battery in my 35 foot 5th wheel.

The power going to the battery from the truck is only a couple amps so yes if you expect a charge of some value a DC-DC would be of value. I opted against anything on my 2022 that Stellantis could use against me in a warranty situation so I didn’t get one.

I have a 150ah Eco worthy in a 36’ fifth wheel with a lithium ready dc converter, 800w solar, and a 3600w EcoFlow solar generator as we mostly dry camp.

 

[phyler]

If you want to charge your batteries while driving, DC-DC is the way to go. I have the Victron XS 50A in my trailer. Just ran the wires from the battery spots to the back of the truck and use an Anderson connector. Has an auto sense so it just turns on automatically.

 

[Cookninaz]

Thank you both very much!

 

[joeycamp]

I know this is an old thread, but still on the subject of my concern. Replacing my two lead acids with a lithium 12.8v 280ah in the 5th wheel. My 22 ram 3500 has just one basic alternator. Saw a YouTube video and the guy mentioned I could do damage to the truck somehow if I don’t get the DC to DC charger. Or maybe I understood him wrong. I’m not too worried about charging the batteries on the road. The battery alone should keep my fridge going for a the time I’m on the road. My concern is damaging my truck somehow.

 

[phyler]

I know this is an old thread, but still on the subject of my concern. Replacing my two lead acids with a lithium 12.8v 280ah in the 5th wheel. My 22 ram 3500 has just one basic alternator. Saw a YouTube video and the guy mentioned I could do damage to the truck somehow if I don’t get the DC to DC charger. Or maybe I understood him wrong. I’m not too worried about charging the batteries on the road. The battery alone should keep my fridge going for a the time I’m on the road. My concern is damaging my truck somehow.

You'll be fine. The truck isn't going to charge your battery much via the 7 way plug while driving.

 

[joeycamp]

Thank you. Charging I’m not worried about. Someone said something can blow a fuse on the truck but he had a 300 amp alternator. I’ll leave a campground fully charged from the site. The most is 8 hours on the road should be plenty to keep the residential fridge going.