I have 48v lithium batteries connected to a Multiplus 2 48/5000/70 in my motorhome. My start batteries are 24v as is the alternator output. I was hoping to use a Phoenix 24/1600 connected thru a changeover switch to run the multiplus while driving. As I understand it the new smart phoenix can also detect the engine running. Is this the preferred method as I do not see any Orion DC-DC units for 24v to 48v that are suitable to use as a charger direct to the lithiums.