I just converted my RoadTrek to a LiFePO4 150AH coach system. I was definitely concerned with overtaxing the OEM 145 Amp alternator as the low internal impedance of the Li pack could easily overload it. Checking it out before installing the DC/DC charger it would easily such 70 amps from the alternator, and I suspect that was being limited by the 18 foor #6AWG line to the rear. I looked into various DC/DC units (there are not a lot out there) and ended up using a 20 amp Renogy DC/DC charger. That draws about 28 amps from the alternator when charging because of conversion efficiency. It is quite cost effective at about $130. Next size up is a 40 amp output, which would draw about 60 amps from the alternator and costs $200. They also make a 60 amp model but would probably be advised to install a larger alternator, like a Nations or something similar in order to use this one. The Renogy has several battery profiles available, including LiFePO4, using DIP switches. So far it is performing well and. of course, does not affect the flooded Pb starting battery.