The new Mando 65 amp alternator
on the YC Grand Banks
(Lehman 120 hp) is driving me nuts. Its a 3-wire alternator
, with output, exciter, and sense wires. The sense wire is jumpered to the output, which should keep the output voltage less than 14.5v, but it just keeps going up. If I rev up the engine
it goes over 15.5v. Installing a ground wire on the alternator case does not help, and neither does putting a new regulator
in the alternator. The alternator puts out about 25 amps at idle, and over 45 amps at cruise
. The alternator shop swears that the unit tests normally on the bench, but I haven't seen it with my own eyes.
The excite wire was going to 12v switched, and there was some discussion on Mercruisers about going through an idiot light. I tried a 1.3 watt light in the excite circuit with no change, and then put a 100 ohm pot in the circuit and going from 2 to 102 ohms had no effect. I'm running out of things to try, and I think my options are another brand alternator or converting this one to external regulation. Any suggestions??