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  #16  
Old 08-19-2002, 07:28 PM
EverclearAtMSU
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you guys are awsome
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  #17  
Old 08-20-2002, 04:26 AM
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[QUOTE]Originally posted by EverclearAtMSU
[B] Along with redoing all the wiring that goes to the alt.

For goodness sake do not just simply replace all the wiring to the alternator. This would make a mess off what is probably a perfectly good loom. If there is a wiring fault it should be easily found and corrected but I can not see this being the problem.

I go along with Beav and his practical experience. If there is over voltage at the + battery terminal there can be no open circuit in the wiring to the alternator unless ther is a separate wire to provide the regulator with a reference voltage which would be very unusual.

A short circuit taking the field to earth need not involve a solid state component and there are components in the regulator that can go open circuit and defeat its operation. There is every indication that the regulator is faulty in spite of what you have been told by the shop that fitted the alternator of which it is part and parcel and your problem is with them. Was it in fact new or a reconditioned unit ?

The only external wiring fault which could increase the output voltage would be an open circuit in a separate dedicated wire from the battery + to the regulator to monitor battery voltage.

If Beav is still tracking this thread he will be able to advise on this. In the absence of such an external circuit the fault must be within the alternator.
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Last edited by Trevor; 08-20-2002 at 04:43 AM.
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  #18  
Old 08-20-2002, 12:15 PM
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^
^
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Yeah, what he said! ^
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  #19  
Old 08-21-2002, 06:29 PM
oab_au oab_au is offline
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Quote:
Originally posted by Trevor


I go along with Beav and his practical experience. If there is over voltage at the + battery terminal there can be no open circuit in the wiring to the alternator unless ther is a separate wire to provide the regulator with a reference voltage which would be very unusual.

The only external wiring fault which could increase the output voltage would be an open circuit in a separate dedicated wire from the battery + to the regulator to monitor battery voltage.

[/B]
Well look mate, I just gota tell yeah, thats exactly what they do.

A seperate sense wire is used, to sense the battery voltage.

The days of using the alternator output wire to sense the battery voltage ended when we started using alternators with over 50 amps.

In the days of old, when the only function of the alt, was to fill the battery after starting the motor. It did not matter that the output wire resistance rose with the charge rate and the reg saw a different voltage due to the resistance. As by the time it was reaching cutoff voltage, the charge rate and the wire resistance, had dropped, so that the reg could read the true battery voltage in time for an accurate cutoff.

Today we have 100amp alternators and so much electrical gear to run, that even when the battery is fully charged, the alternator is still charging hard to support all the gizmos that we now use.

You can now see that there is no time, that the alternator output wiring is at a zero resistance, hence the need to use a seperate sense wire to have a true battery cutoff voltage of 14.7V.

It is in this sense wire circuit that I believe EverclearAtMSU has a fault. The reg used has a fail safe function to limit the output voltage to 16.4V.

This is a circuit of the alt and reg. you can see the connection at terminal 'S'

Harvey.
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File Type: jpg alternator.jpg (69.7 KB, 62 views)
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Last edited by oab_au; 08-21-2002 at 06:53 PM.
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  #20  
Old 08-21-2002, 10:39 PM
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Yes Harvey, that is the usual arrangement I totally agree.

However in respect of the SVX it appeared to be be Òvery unusualÓ as the wiring diagram which I had previously consulted and had in mind, shows a single wire from the battery positive to the fuse box and a single feed from the alternator to the fuse box with all alternator connections bridged at the alternator.

This diagram ( Power Distribution ) I previously referred to when checking on another matter and had noticed this rather strange feature and it had stuck in my mind. After now physically checking the car it is clear that a separate sense wire is in fact used and I should have been sceptical in regard to the hybrid diagram, my fault.

It now becomes apparent that the draughts man could not make up his mind as to whether he was drawing a schematic or a wiring diagram and the result is totally confusing. I now appreciate that he was trying to eliminate the usual horrible mass of lines which appear in most motor vehicle diagrams but a note should have been included to the effect that the drawing is in part schematic.

A long time ago, while biding time while setting up my own Company, I worked for a local car assembly plant and wound up re hashing their wiring diagrams due to much confusion among assembly workers. Therefore I can have no excuses on the basis of ignorance.

A regrettable blue, Trevor.
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Last edited by Trevor; 08-22-2002 at 04:34 AM.
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  #21  
Old 08-22-2002, 03:34 PM
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Smile Shazam!

I guess I've been lucky (or was it my customers? ) over the years as the very few times that this was really an issue (as compared to most failures being totally dead output) rebuilding the alternator or replacing the regulator has been the cure. I see what you're saying and agree, I just think it's less likely to occur, based on my experience, for whatever that's worth. Usually I find that if nobody has monkeyed with the wiring you can pretty much count on it being o.k., 90% or more of the time.

BTW, while the bees are buzzing around nearby... I happened to notice under the hood of a 2001 Ford Taurus today (who knows what they're called in other markets) the alternator output wire is approx. 6 ga. wire. I suppose they grew weary of poor connectors and insufficient wiring causing underhood fires.
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  #22  
Old 08-22-2002, 05:07 PM
oab_au oab_au is offline
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Re: Shazam!

Quote:
Originally posted by Beav
Usually I find that if nobody has monkeyed with the wiring you can pretty much count on it being o.k., 90% or more of the time.

BTW, while the bees are buzzing around nearby... I happened to notice under the hood of a 2001 Ford Taurus today (who knows what they're called in other markets) the alternator output wire is approx. 6 ga. wire. I suppose they grew weary of poor connectors and insufficient wiring causing underhood fires.
Yes the wiring on the SVX is quite adequate, as long as it hasn't been pulled down, spray painted, then put together again in the panel shop

March on 24V

Harvey
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