Rv??
There are (of course) multiple possibilities here, but I will shoot the easy ones first.
This sounds like a bad connection problem. Get a battery terminal cleaner and start there. If that doesn't do it, hook up your original main engine battery and try again.
No Go?
Feel all the connections you can find and one will probably be warm. Disassemble that one, clean it and put it back together and try again.
When it is convenient, put both the batteries that did crank on a charger over night and then take them to a local parts store for testing.
I just spent an afternoon doing this for a boat owner. Since the depression, I have to take any work I can fine.
Matt
