Are the battery terminals aluminum? If so, in the electrical power business, shining them up and coating them with Noalox to prevent the formation of aluminum oxide is common. Aluminum oxide is a good resistor. Passing high currents through a resistive junction will heat it and loosen nuts. That was part of the issues with aluminum house wiring in the 70's and 80's. I lived in such a house and the wires kept coming loose from the outlets due to repeated heat/cool cycles. It was really bad. I had to replace several outlets in the early 80's, shine up the wires and coat the wires before attaching them to the new outlet. Once that was done the issue did not reappear. Fortunately that was a rental house. We moved out and left that mess behind.