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Charging problem

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nocharge

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"I’ve got an ’88 Mercruise

"I’ve got an ’88 Mercruiser 3.7 Liter. When I run the boat, and switch the batteries off, the motor dies. Even at 2500 rpm, above where the charging system should take over I would think. It has an alternator (I think) that’s a bit foreign to me. I'm a good car mechanic, but new to boats.
It’s not belt driven, but instead amounted right on the crank. It’s got two wires coming from it, which go into the voltage regulator. All the terminals on the regulator look pretty corroded. How do I check the alternator and regulator for proper operation. What voltage should I have where?"
 
same problem we all have had w

same problem we all have had with that set up. you can do a search in here for 470 charging system and get any number of posts about the same thing. chances are you voltage reg is bad. . can be replaced but near $ 400. most of us have adapted a 1 wire alternator and brakets and solved the problem. you can get the alternantor and the conversion kit for less than just the reg. good luck
 
It is my understanding that a

It is my understanding that a battery switch should never be operated (changed) with the engine running because it is detrimental to the alternator's components. Your methodology of running the boat only off of the alternator on a regular basis has me wondering why? I would only do that if my battery was dead and someone gave me a jump to get it running again. Interested to know the logic behind it.
 
never take the battery out of

never take the battery out of circuit with the engine running. The alternator will "full field" and max itself out frying itself.
 
"nocharge

((I'

"nocharge

((I'm a good car mechanic, but new to boats.))

Hmmmmmmmmmmmm !!!
crazy.gif


Spot on as per normal Mista Hays its a great way to fry an alternator.

Cheers
Peter C"
 
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