[B_man_Al]

Ed ..
I agree that the diode can fail if it is not properly heatsunk in the cutout. When charging the battery, the power dissipation will be in the order of 8-10W at 10A charging current. This will produce a lot of heat which must be conducted away from the diode for it to be safe. You can see this with the large finned heat sink in a typical GM alternator