250XS alternator voltage spike

[bep078]

I have a 2010 250XS with 95 hours. Alternator broke the rotor. Had it "fixed". After 30 mins, rotor broke again. Bought a new alt from DB Electrical. I gave them my alt part number and sent me one identical to the one i had made by Delco. Installed it and on idle all was fine. (14V) once i went over 2000 rpm voltage spiked to 17V and motor went into guardian mode. Tried my mates alt (oem) and all was fine.

Does the merc alt have a voltage regulator built in? Or is the one they sent me defective? Or perhaps i can install a voltage regulator on the red fused wire?

Any input will be greatly appreciated.*

Tnx.*

[bep078]

ttttt