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Old 25-02-2009, 18:26   #1
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ALTERNATOR//DID YOU KNOW........

Did you know that if your boat had a alternator with a external regulator and you replaced it with a alternator with a built in regulator and if you don't disconnect the old external regulator you will fry your whole system.

This happened on a boat that I was working on,, The auto-electrician explained it this way... If you don't disconnect the old external regulator the power is going through the built in reg. and then through the external reg. it has no direct connection with the battery's there-fore it will keep charging flat out as though the battery's are low and cook the battery's and end up burning out a diode in the alternator I think he called it the "status"

The battery's on the boat we were working on were only 2 years old , 12 new battery's and a new alternator and labor and expense mistake
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Old 26-02-2009, 07:41   #2
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No...I didn't know that...Thanks
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Old 26-02-2009, 15:30   #3
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Doesn't sound quite right to me. The internal regulator senses the alternator output voltage, and keeps it at a predetermined level, say 14.2V. The output of the alternator doesn't go 'through' any regulator--internal or external--it goes to the battery. An external regulator senses battery voltage, and adjust the field or exitation current to keep the battery voltage at the right level. If you replace an external regulator with an internal one, there is usually no field connection to hook the the old external regulator up to.
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Old 26-02-2009, 16:31   #4
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Quote:
Originally Posted by donradcliffe View Post
Doesn't sound quite right to me...
... If you replace an external regulator with an internal one, there is usually no field connection to hook the the old external regulator up to.
Exactly ...
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Old 26-02-2009, 19:42   #5
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Sounds like the catch is in how you define "replace".

If the old external regulator was disconnected--no problem. Most likely, it was reconnected unintentionally and the new alternator couldn't figure out who was boss. Working on bits without understanding the whole system that is being worked on, is not a good way to go.
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Old 26-02-2009, 21:28   #6
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donradcliffe,, Maybe I did not explain it correctly,

It all started off flat battery's, we would start the gen-set up charge the battery's but they would be flat within 2 days

On comes the auto electrician,,, and he found the alternator was stuffed and also the house and main starting battery's, On Monday when we installed the new battery's and reconditioned alternator.

Now when he was trying to check the charge rate said there was a problem and as the boat was built in 1991 trying to trace where the additional wires were going this is when they found the external regulator now he said the ordinal alternator could not have a built in regulator and when they put a later model alternator on with the built in regulator they forgot to disconnect the old external .

Now all I know is what he said; The power from the alternator goes to the battery's via the built in regulator anything in the way will inter fair with the current flow and the fact that it was going via the external the built in regulator was unable to determine if the battery's were charged

What I can tell you we have one very pissed off owner
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Old 26-02-2009, 22:27   #7
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"trying to trace where the additional wires were going "
I've played that game. If there are wires and you don't know what they are for, either you trace them out or you cut them. You don't remove them--but you cut them, and see what happens. Among the odd things I've found were a 'secret switch' apparently installed as an antitheft switch, and punked out household zip cord, powering the binnacle compass lights. Oh what fun.

And then there was the thoroughly used car I had, where the alternator blew out ("but it can't blow out, there's a fusible link wire to protect it!") because the bozo PO had installed a second duplicate alternator harness, in parallel with the original one, effectively defeating the (now two) fusible links.

Chalk it up to "**** happens" and thoroughly used boats, owned by a guy in a fright wig and round red nose. And thank the gods that it only blew up the alternator, instead of burning down the boat.
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