[jwetering]

I had this problem, and solved it by installing a bigger battery.

The story I have heard but never verified is that there is an undersized/poorly made crimp on the main ground wire which limits the flow of current during startup.

This isn't as much of a problem when the engine is cold because the tolerances are looser. When the engine is hot though the tolerances tighten up and the flow of current is barely able to overcome the frictional forces.

Like I said - a bigger battery solved my problem and I needed a new battery anyway. In your case I do believe that fixing this crimp will solve your problem.