What battery do you have?? I run nothing smaller than groupe 27 batt. , plus nothing smaller than 1-0 batt cables, neg. and positive. i've ran 632 big block chev. with no hot or cold start issues.
I believe the heat is affecting the solenoid rather than the starter motor. It’s still working fine on cold starts. Hopefully get it out in the next few weeks. Want to do a torque converter change anyway.