If I were you, I'd list what my batteries are, size of wiring, distance of run and if you are willing to upgrade wiring. Then call Randy at Best Converter. 100 amps may be over kill.
I might disagree with the idea that the generator is a better option than an alternator. This depends on your alternator size and charge line size. It might even be cheaper to run the engine alternator than a generator. Check out the fuel consumption, per hour, on your genny. Genny's are convenient but not always efficient power converters, especially just to plug into the rig for running a converter/charger. You could use a 3 stage battery charger straight from genny to batts.
Now if you are running the genny in the am, while using the micro to cook or the electric coffee maker, than you can charge batts at the same time then combining the two requires the genny. Just charging batts does not.
