You are right about resistance causing heat. It can be be a dirty terminal, a bad connection where the wire is molded into the connector or a bad connection at the starter or ground. Remember that 6 volts pulls twice the amperage as 12 volts and you need thicker cables. I run over the road trucks, and we replace cables if they get warm at all. A failure away from home can be expensive. A dragging starter, that is a starter with worn out bushings, will draw more current. Try to isolate where the heat is coming from.
