I thermoepoxied a Ktype thermocouple to my alternator's Stator casing.
I wish casing temps were more indicative of rectifier temps.
But my data with this thermocouple location shows the alternator casing heats excessively only when not moving and at or near maximum output.
At 65MPH and 80 amps output the casing averages 109f.
Idling hot at 54 amps output and that 109f increases to 160F in under 2 minutes.
Driving 25mph at low engine rpms also causes the temperature to rise quickly.
My observations indicate alternator casing heat is of course dictated by load, but also by airflow not only caused by more rpms spinning the alternator fan faster, but by underhood airflow.
Underhood airflow is a big variable vehicle to vehicle.
How representative of actual rectifier heat, vs the casing heat is, is unknown to me. Guess i could run another thermocouple to (+) output stud to better represent rectifier heating.
Right now I only have 90AH of agm battery, total, and have to rely on lights and blowermotor on high and other electrical loads to keep the alternator maxed out for these tests.
I once considered making a cold air intake to feed my alternator. Easier was to install a simple heatshield between alternator and nearby exhaust manifold and this seemed to increase hot idle speed amperage by about 5 amps.
