Originally Posted by Bill Gail
It's not just the converter/charger that needs to be addressed when converting to Li-ion batteries .
The engine alternator can overheat from the additional load of the Li-ion .
There are several solutions , with the apparent most popular being the installation of a DC to DC charger .
Thi Li-ion battery upgrade is one improvement that requires some in depth research .
Yes, in a motorhome for sure. But not so much in a Travel Trailer like the OP's Minnie Winnie. The wiring between the tow vehicle's alternator and the 7-pin plug is so long and the gauge so small that very little of the alternator's output makes it to the battery(ies).
In this case, not to protect the alternator, but to improve charging while driving, a DC2DC charger may be beneficial, but if the TT has solar panels then the AUX charger may not play that large a part.