Martin, EV5 diagnostics has a logging function that can record about 5 minutes of selected data as an Excel file. I suggest asking your dealer to log rpm, EMM temp, and all of the voltage and current readings on the current EMM and the replacement unit as well if needed.
I will certainly look into that Rick. Here is a thought. The EMM is internally rectifying and regulating the correct voltages which would suggest that any of the heat generating components that would be attached to the water cooled heat sink are still working. This, and the fact that no overheating has been logged, would suggest that overheating is not the issue here. I have one of my previously failed EMMs apart and have ordered a replacement electrolytic capacitor and am trying to source a particular schottky diode made by a company called Vishay. The capacitor was not failed but did not meter at its correct value, the diode I have not yet taken out if circuit as I would like a replacement to compare it to and don't want to desolder a surface mount component without having a replacement. I am not sure the diode has failed but I suspect it has. I cannot find it in Vishays listings and am waiting on a reply from them as to the availability of the part. Should it turn out that these are the failed components then it would suggest that they simply are borderline in their design to be able to handle the initial current demands to recharge a battery after start up.