Dead Alternators

[Neil_P]

For some reason I keep destroying alternators and at 60 pound for a repair or 200+ for a new one this is getting rather expensive. Not to mention the annoyance factor. So far this season I have had 2 on one engine go and 3 on the other. I think that one failure may have been caused by a water leak dripping onto the alternator. The batteries are all in good condition. Has anyone any suggestions? Both circuits are independant and I can't believe I have a fault on each. Boat is now out for the winter so I have a few months to sort this out.

Also I have been told that the alternator on Volvo AQ151 is the same as that fitted to a Volvo 240 car. Can anyone confirm this. Car one is half the price.

regards

Neil.

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[hlb]

Take old alternator to an auto electician for repair, or to find you a new one.

<hr width=100% size=1> <font color=blue>No one can force me to come here.<font color=red> I'm a volunteer!!.<font color=blue>

Haydn

 

[jonjo]

Re: Bad switch

Any chance that you have a faulty ignition switch that can leave the alternator charging nothing when the key moves from heat-start-rest?

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[david_bagshaw]

What do they tell you failed each time on the repaired one? It should give a good lead to the cause.

Otherwise I would look for earthing / return breakages. or some stray current etc


Do they fail underway, or worked last week but not now?


<hr width=100% size=1>David
<A target="_blank" HREF=http://www.euroboating.net>http://www.euroboating.net</A>

 

[Neil_P]

So far I have had the regulator fail once and the windings blow a hole in themselves. Also the connection between the regulator and the winding blow. The port engine alt failed while on the move the starboard has just failed after being ok 2 weeks ago. Started the engine yesterday and nothing charging.

Neil

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[BarryH]

The alt's on the cars is totally different from the ones on your 151's. The marine ones are Bosch and so are the car ones. The the similarities end. The marine ones are spark protected. Where as the auto ones are not.

What is actually failing on yours?

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[david_bagshaw]

regulator fail once and the windings blow a hole in themselves. sounds as if it worked it self to death.... stray currents perhaps



Also the connection between the regulator and the winding blow. unusual failure point



starboard has just failed after being ok 2 weeks ago..... strange


personaly I would look for defective wiring to the alternator, something that is powering the field circuit while you are away, crud on the output wiring leading to excessive resistance.

How old is the engine & wiring?

<hr width=100% size=1>David
<A target="_blank" HREF=http://www.euroboating.net>http://www.euroboating.net</A>

 

[Neil_P]

I believe the wiring is original which makes it 14 years old. I plan to re-wire the charging circuits over the winter before replacing the alternators. This will also include checking the rest of the wiring for dodgy connections etc.

I cannot find any back feed while turned off and all batteries stay fully charged.

Thanks for all the advice. Still not convinced about the difference between auto and marine alternators except for the cost.

Neil

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[greystones]

Is there any chance with a faulty battery C/O Sw that the connections might be broken momentarily ( is the sw as old as wiring ) to the batts when the alternators are running. This would result in huge V rise, enough to cause damage. Just a thought.

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