the negative terminal is getting hot and smoking?

Hello,

The negative battery cable is getting hot and smoking due to having high resistance connection at the battery post and or the ground at the frame.
This is typically due to corrosion, faulty wire or even a loose connection.
So first inspect the ground, corrosion on the ground can create this issue.
Many times, the best solution is to replace the wire as there is likely internal damage to the wires due to smoking and overheating.
It is very important to have clean and secure ground as well as a clean battery terminal.

Please let me know if you have any questions.
Thank you.