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Old 09-01-2013, 03:50   #1
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Alternator Noob Question

Dear Members,

I'm quite new with electronics and electrical subjects. That is why I ask for your patience with my easy question.

I've some wiring connection problems. I think I know the answer, but I don't feel confident enough to test it before I hear some opinion from you, more experienced users!

My problem: to wire an alternator which has an battery1 (to supply the magnetic excitation field) and load (another battery2 and some LED, lights) with different grounds!

In my head, since the energy transfer between the stator and the rotor are made through magnetic fields, this would not be a problem if they were not connected together inside the alternator. And that is my doubt. Is it?

I saw some "isolated ground alternators" on the internet. Is this the solution to my problem? I mean, all I have to do is to buy a ground isolated alternator, connect the excitation field in the battery1 and the load to the alternator output? This way they would be electric isolated?

Thank you very much for your attention!

Sincerely,

A noob.
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Old 09-01-2013, 06:04   #2
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Re: Alternator Noob Question

The field supply is controlled by the regulator which is also connected to the output. All your DC grounds on a boat should be connected together, Avoid multiple floating DC grounds
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Old 09-01-2013, 06:14   #3
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Re: Alternator Noob Question

Quote:
Originally Posted by fabiomolinar View Post
Dear Members,

I'm quite new with electronics and electrical subjects. That is why I ask for your patience with my easy question.

I've some wiring connection problems. I think I know the answer, but I don't feel confident enough to test it before I hear some opinion from you, more experienced users!

My problem: to wire an alternator which has an battery1 (to supply the magnetic excitation field) and load (another battery2 and some LED, lights) with different grounds!

In my head, since the energy transfer between the stator and the rotor are made through magnetic fields, this would not be a problem if they were not connected together inside the alternator. And that is my doubt. Is it?

I saw some "isolated ground alternators" on the internet. Is this the solution to my problem? I mean, all I have to do is to buy a ground isolated alternator, connect the excitation field in the battery1 and the load to the alternator output? This way they would be electric isolated?

Thank you very much for your attention!

Sincerely,

A noob.
"Isolated Ground" vs. "case ground" with an alternator just means that it does not use the alternator case, a rusty engine, engine paint, corrosion and multiple dissimilar metals for the neg to pass through before picking up the neg cable back to the battery. It gives you the ability for a clean direct path and does not use the case of the alt or the engine for this path.. On metal boats this also means the alt can be wired "isolated" from the engine.
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Old 09-01-2013, 07:35   #4
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Re: Alternator Noob Question

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Originally Posted by goboatingnow View Post
The field supply is controlled by the regulator which is also connected to the output. All your DC grounds on a boat should be connected together, Avoid multiple floating DC grounds
And what do I do in the case that different grounds are strictly necessary?

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Originally Posted by Maine Sail View Post
"Isolated Ground" vs. "case ground" with an alternator just means that it does not use the alternator case, a rusty engine, engine paint, corrosion and multiple dissimilar metals for the neg to pass through before picking up the neg cable back to the battery. It gives you the ability for a clean direct path and does not use the case of the alt or the engine for this path.. On metal boats this also means the alt can be wired "isolated" from the engine.
So, even though they are "isolated ground" (due to the fact that it is not connected to the case), are they connected to the same ground?

One more time, is it possible to have different grounds in an alternator? One for the excitation and another to the output?
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Old 09-01-2013, 08:03   #5
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Re: Alternator Noob Question

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Originally Posted by fabiomolinar View Post
And what do I do in the case that different grounds are strictly necessary?



So, even though they are "isolated ground" (due to the fact that it is not connected to the case), are they connected to the same ground?

One more time, is it possible to have different grounds in an alternator? One for the excitation and another to the output?
You may want to hire a professional I think it would be your best bet.. I'd hate to see you damage something expensive.
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Old 09-01-2013, 08:25   #6
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I don't understand why you need two separate grounds. Are you doing something exotic?
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