Alternator Help

[mjm]

I am having a bit of trouble with my Yanmar 3GM30F. I went out one day for a sail & could not start the engine I have a flat battery I did managed to start the engine by jumping it from the domestic batteries. Then I noticed that the engine was not charging the batteries at all. I put a meter on the alternator there was no current at all. When I was doing this I notice that a wire that was connected to a plug in the back of the alternator was not connected i think this was the D+ line. So I took the alternator off & re-connected the wire back in to the plug at the same time I also re-connect the other wire on the plug as well. When I put the alternator back I started the engine & tested the voltage again & there was no current I then pulled the plug off the alternator & have a 12.4v current. So either the alternator is not working or could it be that I re-wired the plug the wrong way. Can any one help what happens if I swap the wires on the plug or any thing else I can do.

Thanks

Mike


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[Chris_Stannard]

Sounds like you may have blown the regulator on your alternator. If you have and can take it off any competent repair place should be able to fir new regulators in a very short time.

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[Alex_Blackwood]

I agree with the previous reply. Sounds as though the regulator diodes, or at least one of them has gone. This can be caused by the alternator running open circuit - your disconnected wire! I wouldn't go swapping wires around and in anycase would want to identify the other wire you reconnected before runnining the alternator after repair.
Good Luck


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[mjm]

While I think your right I would like to find out which wire is right on this plug I have looked though the manuals but no joy. The plug has one spade that running horizontal & one virtical I think the virtiacl one is the D+ line can any one help.

mike


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[mjm]

Ok the story goes on. On the boat I swap the wires & get 14.8v but when the engine is run faster I get 15v. So I take the Alternator out of the boat & take it to a Alternator specialist they did a bench test & say everything is ok. But I am still unsure which way the plug should be wired. I have looked on the web for that data sheets for the Hitachi LR135 but cannot find one. I did ask the specialist but forgot to write it down he did not mention the D+ but the sensor wire which I thing is the same. One other point is a have a strling marine smart regulate connected. I do now think every thing is now working. But how can I be sure without destroying my batteries.

Ta

mike

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[hugh_nightingale]

Sounds like you might just be lucky.

15V would normally be a bit high for charging batteries, it over cooks them.
However, the fact that it IS 15 and not something higher means that it is regulating.
If the sterling has diodes in the circuit it may be that it is compensating for the loss (in the diode). Check at the battery terminals. 14.4V on high charge and 13.8 on trickle should be sufficient.

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[mjm]

I have now spoken to sterling they said 15v also ok & alright upto 15.5v. As one of the battries is dead I am going to put it all back with a new battries & see what happends xfingers all will be well.

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