First thing I would do is check to see what the starter draw is. If the complete cable gets hot it sounds like to much starter draw which will make the complete cable hot. If it has high resistance somewhere like even a dirty connection at the battery cable end where it goes on the battery then it would only be real hot at that point of high resistance. The complete cable would not be hot. I would check starter draw before I did anything else. And also you can do voltage drop test to see if it has a bad connection in the circuit and if it does you can trace down where with voltage drop test. But the whole cable getting hot sounds like to may amps going through the circuit and a starter draw test will let you know where that stands at. Just be sure the battery is fully charged when doing a starter draw test as a weak battery can give false readings. Good luck , Ron