Yanmar 3YM30 Alternator Regulator Problems

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TradewindSailor

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I have two 3YM30's ... engine No's E04811 and E04809 circa 2006. Approx 1000 hrs on each.

Both 60 watt alternators have failed ..... the regulators started fluctuating at about 13.8V - 14.0V, causing noticeable surging of the engine as the alternator output oscilated between say 20 Amp and 30 Amp.

The problem was cured by installing new alternators.

I rather suspect that the regulators failed due to heat.

The Yanmar documentation is hopeless as they do not define the alternator specs at all, except that they are 60W.

I have to date received no help from the dealers, and can't get into contact with the Yanmar Technical Dept .... which seems only accessible to dealers.

When I asked a Yanmar dealer in San Diego for a workshop manual, he was sent a 3GM manual instead of the 3YM .... after I waited 2 weeks. I am now in Mexico.

I would be interested if anyone else has had problems with the Yanmar Alternators ..... and whether Yanmar have taken any interest in the problem.
 
If they are the same as as some other alternators the bolts holding it together also act as electrical connectors. Often corrosion can be a problem
 
The failure mode of the alternators as you describe it sounds like bad sliprings or worn brushes. Perhaps sticky brushes in the holders.

The brushes conduct a small current for the field coil (rotor) the amount of current controls magnetic field which determines voltage output. Thhe brushes are a type of carbon which bear on the rotating slip ring a ring of copper or brass. If the contact is not good then arcing occurs which makes the contact worse. It is easy to remove the brushes on most alternators and you can see the slip rings which should be reasonably clean and smooth.

I can't imagine the regulators failing due to heat as they are made for pretty hot conditions. Try Oz in 40degrees in the shade in a traffic jam. That is hot under bonnet of a car. I -presume you mean original alternator regulators.
Perhaps you should persue the alternator manufacturers.
good luck olewill
 
I know it's a long shot but do you have any intelligent battery chargers connected to the system ~ if you do are you sure it's not them driving the alternators nuts?
Peter.
 
Well, both of the modern Yanmars (a 1GM10 and a 2GM20) that I have had recently have Hitachi alternators, so you could try enquiring from Hitachi rather than Yanmar.

We generally find that you can get better service for an alternator fault by taking it to an auto electrics workshop (available in most towns), rather than a diesel engine workshop/supplier.

As to getting help/response to a complaint of a failure of a Yanmar under warranty, I received no useful response whatsoever from the distributor or from Yanmar, but had to pay to get a replacement part and fitted it myself.
 
I suspect the problem may be caused by connecting the two outputs directly together. This can cause regulators to oscillate. I have experience of this with industrial power supplies. The cure is either to make one do all the work or a proper current sharing design. Or to use each alternator for a different bank of batteries.
 
Thanks to all for your comments and suggestions.

The oscillating problem occurs whether I have either or both alternators charging the battery bank.

As far as I'm aware both alternators should be able to charge the same bank without damaging the regulators. As the new battery bank is 700 amp hrs, the voltage perceived by each alternator should be relatively stable.
 
Thats a pretty large battery bank to be charged by 60amp alernators, sounds to me like they're overloaded.I have a 3Ym30 with an 80amp alternator into 3 x 110 a/hr service batteries and a 75A/hr engine battery controlled by a intelligent split charge management system. On start up it will pull 50+amps then regulate to keep the heat and charge rate under control. Its backed up with a wind generator so the batteries rarely get heavily discharged.
My suggestion would be to consider the biggest alternators the engine can run without compromising the power, and fit a battery management system.
 
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