1973 Dodge Sportsman motorhome

Hi! I have recently purchased a 1973 dodge sportsman motorhome. I went to change the battery because the one in it was too small. After replacing the battery I have no power to anything at all and it wont even try to crank. When I put the new battery in I noticed a smaller red wire with a flat plug on one end hanging loose. Where does this go and what is it for? the new battery has full juice but I have no power to anything. No lights no radio…nothing! Any help would be appreciated also if anyone knows about these motorhomes that would be great, could use all the help I can get.

Did you mistakenly reverse the connections and see a few sparks when installing the battery?

That smaller red wire is most likely the power for everything except the starter. Nothing needs the amperage that large cable can deliver except hte starter. It should be connected to the positive (+) side of the battery.

…after verifying the connections are correct, of course.

Hey firsttimerv . . . are you in Pennsylvania? I just saw a mid-70s Dodge RV for sale close to where I live? Maybe I can help. Rocketman