I had that converter and installed that upgrade. It worked fine, I am really happy with it (it is in my truck camper). Now the bad news. The magnatek that you will be replacing (it's an upgrade everything except the front door, basically) is a total piece of junk. Known for several things - amount them boiling batteries dry in short order and catching on fire...If you are going to 24 volt, buy a 24 volt converter/charger from the same guy, he is an excellent vendor, and be done with it. You don't need a traditional converter, which in an RV is the AC distribution, the DC supply and the DC distribution all in one code approved box. You will want to have your own separate AC panel and build a nice DC distribution system your self, so a plain charger is better for you.The main difference between a charger and a converter power source is the charger is optimized for charging and maintaining batteries, so it has the multi stage charging. A converter is designed to supply DC to a house system, so it often has multi sage charging but all at one voltage, done by current limiting, or has a separate "charge wizard" that only does multi-stage charging on command. The unit that you show, that I have, is a constant 13.6 volts but maintenance mode is virtually no current. According to it's book, anyway.
My theory is that you want to be able to charge all of the batteries from the engine, somehow, and charge all of the batteries from the pedestal 120 vac, somehow, and relatively quickly at that. Does me no good on the road to need 48 hours to top off my house bank. So my solution is all 24 volt system, all charged from the alternator, with switches to isolate when required. A large-ish 24 volt battery charger that can charge everything, again controlled with switches. A Vanner to derive 12 vdc for small house loads.I would install a separate alternator as a valid choice, but about my last choice. It's a good idea, I just think the simpler the better. Mind you it has the benefit of redundancy. Nothing like an extra alternator when you run out of electricity... There is no way I would not have a charger, though.Brian
I'll see to it there is a place for you if you can get there...Cable