George,

 

Most aircraft alternators had the ability to kill output from the alternator by removing voltage to the field coils of the alternator.  However, most all automobile alternators need only the initial  battery voltage to the field coils to start producing voltage.  Once started, removing voltage from the field coils WILL NOT  shut down the alternator.

 

I discovered this myself.  If I start the engine with the alternator field coil Circuit breaker in – then the alternator produces voltage as expected.  However, I found when I pulled the alternator field coil CB AFTER the alternator started producing voltage – I could not shut it down.  If I started the engine with the CB pulled then the alternator never started to produce voltage.  However, I am told that in some alternators there is sufficient magnetism retain in the metal that they can start producing voltage as soon as they are spinning.

 

So a number of folks modify auto alternators ( I think they are just as good and a whole lot cheaper) to remove the ability of the alternator to get voltage for its field coils internally.  Then the put a CB in the field coil voltage line and can shut down the alternator at any time.

 

I do not have this mod as I’ve never had an alternator do anything but fail to produce sufficient voltage, but it appears there have been cases where the alternator ran wild and produced high voltage sufficient  to damage equipment.  Naturally you don’t want this in an aircraft , so the best of both worlds is to buy a good quality automobile alternator and modify it.  A number of folks have successfully done this.  My personal experience has led me to leave the alternator as it is and so far that has worked fine for me.

 

Ed

 

 

Chris, Al , Group,

       Here is link for modifying the stock Mazda alternator for an external regulator..........

 

        http://home.earthlink.net/~timrv6a/alternator.htm
Kelly Troyer
"Dyke Delta"_13B ROTARY Engine
"RWS"_RD1C/EC2/EM2
"Mistral"_Backplate/Oil Manifold

 

-------------- Original message from "Al Gietzen" <ALVentures@cox.net>: --------------


> Chris wrote:
> I am running the expensive B&C regulators on both systems with
> the stock alternators with the internal regulators disabled.
> -----------
>
> The question that flashes into my mind is "how did you disable the internal
> regulator?"
> Opening the internal connection from the output that normally powers the
> regulator does not keep the regulator from operating. I'm just wondering if
> there is some issue with your external regulator maybe providing the field
> current to the internal regulator. Perhaps worth re-evaluating that setup.
>
> Al
>
>
> --
> Homepage: http://www.flyrotary.com/
> Archive and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html

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