Re: Melting Marinco plug on my Honda EB3000 generator.
Any sign of burning, melting, or discoloration around the contacts on 30A Marinco connections means that one or both of the connectors should be replaced!
The problem can occur for several reasons:
1. The 30A connectors can't really take 30A continuous current. They are an old and terrible design, and should never be loaded more than 23-25A continuous. The Freedom 20 has a max draw of 21A, but Xantrex chargers have a high PF loss and draw could be higher. And, you can't run anything else while you're running the Freedom 20 with the batteries low, or you'll severely overload the connectors.
2. As noted above, connectors need to be kept very clean and tight. Care should be taken to ensure that the pins fully engage, and the plug is twisted to "lock".
3. "Copper creep" can happen as well, so periodically it is a good idea to take the connectors apart if you can and tighten the screw clamps on the three AWG10 cable connections. For molded connections this isn't possible, and the cord needs to be replaced, or the ends cut off and fitted with new connectors.