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Old 29-11-2021, 16:59   #1
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Running with a faulty alternater ... OK?

Hi all.
I have a twin engine catamaran. 2x 20hp MD2020 Volvo Penta diesel engines.


The port alternator is faulty ... ie not prducing any current.


Is it ok to just continue using the engines as is? I have enough charging via solar and a good starboard alternator. I am happy to just let the port alternator "free-wheel" if is not causing any problems?
Thanks for your advice in advance
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Old 29-11-2021, 17:02   #2
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Re: Running with a faulty alternater ... OK?

Depending on how things are wired The port engine battery will Likly die after several hours of motoring. Then not start or run.
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Old 29-11-2021, 17:09   #3
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Re: Running with a faulty alternater ... OK?

Thanks for that.
There are 2 voltage regulator relays. My understanding is that all the batteries (2 start and the house bank) will still be charging
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Old 29-11-2021, 17:14   #4
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Re: Running with a faulty alternater ... OK?

Actually .. I have been running like this for 6 months and the battery is fully charged
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Old 29-11-2021, 17:39   #5
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Re: Running with a faulty alternater ... OK?

Quote:
Originally Posted by Kurlie1 View Post
Actually .. I have been running like this for 6 months and the battery is fully charged

Well there's your answer

We have been going several years without an alt now and have a $200 victron smart charger on the starts.
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Old 29-11-2021, 18:12   #6
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Re: Running with a faulty alternater ... OK?

My concern was not so much for the battery but that the free wheeling alternator might be causing some sort of damage to the motor/system.
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Old 29-11-2021, 18:30   #7
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Re: Running with a faulty alternater ... OK?

Bit of a silly post . Why don't you fix it ?
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Steve .. It was the last one that did this !
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Old 29-11-2021, 18:47   #8
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Talking Re: Running with a faulty alternater ... OK?

"Silly post"???



Here was thinking this was a friendly forum


Actually nobody has answered the (silly) question ...



Lets rephrase it as simply as I can.


Does a faulty alternator (running via the belt) cause any problem with the motor.
IE... reduced h/power output ... drag on belts etc..
Or does it just freewheel quietly?
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Old 29-11-2021, 19:02   #9
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Re: Running with a faulty alternater ... OK?

Quote:
Originally Posted by Kurlie1 View Post
"


Does a faulty alternator (running via the belt) cause any problem with the motor.
IE... reduced h/power output ... drag on belts etc..
Or does it just freewheel quietly?
There will be some drag
Disconnect the belt and there won't be.
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Old 29-11-2021, 19:21   #10
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Re: Running with a faulty alternater ... OK?

Thanks for the reply Simi.


For the sake of the stock (and cost!) of the V belts I have I will just leave it as is.


Cheers
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Old 29-11-2021, 20:09   #11
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Re: Running with a faulty alternater ... OK?

No it will not cause any problems. You can disconnect the belt to make sure that the alternator is truly free of any internal resistance like seized bearings. That happened to me in the car once and the belt just stopped melted and broke into a billion pieces.
I am not familiar with your motor but if you decided to leave the belt off then I guess your water pump wont work either.
So....assuming it free wheels .. no harm is done to the engine. To be safe you can also disconnect the wiring in case there is some short inside the alternator that potentially screws up your electrical, but given that it has not worked for a while and all is well, you should be fine.

Abe
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Old 29-11-2021, 20:27   #12
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Re: Running with a faulty alternater ... OK?

Excellent repy .... Thanks Abe
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Old 29-11-2021, 20:35   #13
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Re: Running with a faulty alternater ... OK?

Quote:
Originally Posted by sailingabe41ds View Post
.
I am not familiar with your motor but if you decided to leave the belt off then I guess your water pump wont work either.
I forgot that some engines are like that

Ours is not, water pump is stand alone on its own belt
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Old 29-11-2021, 20:51   #14
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Re: Running with a faulty alternater ... OK?

The load that an alternator puts on an engine and belt is dependent on how many amps are being produced. A fully charged battery is receiving no amps (or very few) and the alternator is essentially "free wheeling"
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Old 30-11-2021, 11:00   #15
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Re: Running with a faulty alternater ... OK?

You should be able to take off that alternator, take it to a rebuild shop, and get it repaired for under$100 (US). Since you say it’s been bad for 6 months and the start battery is charged, your question is silly.
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