Hemi E-torque and charging Lithium Batteries

[Kathy&Jim_Imagine]

I've been looking for information on charging my TT lithium batteries off the truck while traveling. I have the E-torque box (starter, generator) and haven't been able to find anything specific to this. The e-torque system as I understand it is a 48v system while the truck is 12v. There is a battery installed behind the rear seat for this system. That's my understanding in a nut shell.

With a normal lead acid or AGM battery in the TT the truck provides 12v to the trailer and some of that power is used for charging the trailer battery.

If I have lithium batteries, will I hurt the trucks charging system? I have read many posts in the forum about this topic but not one that involves the e-torque system that I'm aware of.

Next, If I decide to get a dc-dc charger, I'll assume it will get connected to the trucks 12 battery under the hood like as I've read in other forum posts? Just wondering how the e-torque system might differ if at all with installing a DC-DC charger.

[Jkwilson]

The Etorque gives you two electrical systems. The generator produces 48V which is used both to help power the truck and also to feed a DC-DC convertor to provide 12V power for accessories and to charge the 12V battery.

The trailer charge circuit obviously comes from the 12V side of things, meaning it places a load on both the generator and the DC-DC converter.

My concern is that converter may be a weak point if one tries to supply too much power to the trailer. But that’s probably not a concern with normal factory wiring regardless of the battery type since the voltage drop in the small wire which limits the current flow typically to less than 10A.

if you add a DC-DC convertor to your truck to get more current to flow, the potential exists that it could shorten the life of the existing DC-DC converter. Speculation, since I don’t know specifics of how the system is designed.

IMO, the better solution would be to add a second 48-12 convertor near the hitch or even all the way to the trailer and use that to charge the trailer battery. The wiring at 48V would carry significantly less current, so could be smaller. There could be safety concerns with this method as some guidelines would consider 48V high enough to be a safety risk. But without knowing the specifics of how the 48V system works, that could be more complicated than it seems on the surface

[Kathy&Jim_Imagine]

Jkwilson Thanks for the feedback John. I know my truck has two electrical systems as you mentioned. Interesting idea on using a second 48-12 converter as I was thinking I would just go with a 12-12 off the trucks battery. But as you pointed out, and if I understand correctly, this might overtax the system. That's what I'm trying to find out so if I decide to go that route, I'll be good.
If I just leave well enough alone and simply continue to use the TT plug's 12v, doesn't sound like that will be an issue either. Just less current supplied. Appreciate the thoughts.