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  #1  
Old 06-13-2018, 07:19 PM
Mr Charles's Avatar
Mr Charles Mr Charles is offline
 
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Location: Near Springfield, MO
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Default Alternator wiring help please

Sorry for the long explanation, but necessary I think...

I am currently re-vamping my 4 I have owned since 07. Was originally built by another in the late 90's in Canada. Put it in the shop a couple of years ago and what started as a change to the longer gear legs has morphed into a complete repaint, epoxy cowl, glass panel, autopilot install...and on and on! Along the way, most of the original wiring has been "fine tuned"...re-routed, bundled, resized, replaced or added to. So now I am trying to improve on the original wiring concerning the alternator wiring. The original system had the B lead running thru a toggle (labeled "alternator) next to the master...It also had a "push to test" lamp, on a wire that run to alternator. So here is one of the issues. I took photos when I disassembled, but unfortunately I guess I had already pulled off the faston connector of the wire that led to the test light. I also removed the test light, and not sure where the + lead was connected (has a ring terminal on it still). So I started investigating the alternator to determine proper wiring. Here is what I have discovered...

The alternator is a Hitachi. No numbers on it that I can find. It has an F and N spade terminal configuration. The wire from the test light was hooked to one of these two. My research is indicating this was an externally regulated alternator...BUT...there is definitely not an external regulator. It does have a sticker on it showing where it was overhauled by "Aeroelectric LTD" from Canada...probably in the 90's. Is it possible they modified this for an internal regulator? And if so, was the test light then connected to the N terminal? Or was 12v supplied thru the test light to the F (field) terminal? I will not be using the Push to Test warning light with the Skyview taking on that job. But I am totally confused now as to whether this alternator is internally regulated or not, and if I need to provide 12v to the F terminal...either another "toggle" or pull-able circuit breaker?
Can anyone help me with deciphering all this? (I am decent with basic electrical, but not a whiz by any means...)

Charles
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  #2  
Old 06-13-2018, 08:12 PM
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bret bret is offline
 
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The B lead should not be disconnected while the field and regulator are powered up, regulator damage may occur, I would run the B lead to the non battery side of the master solenoid. On most alternators the F, Field spade is powered up sees battery voltage and can be connected thru a switch to kill the output. if this is internally regulated, the F gets battery voltage, if it is externally regulated, the F connector receives varying voltage from the regulator.
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  #3  
Old 06-13-2018, 08:45 PM
Mich48041 Mich48041 is offline
 
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A google search turned up these:
http://repair-manuals.blogspot.com/2...74-models.html
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http://s7d9.scene7.com/is/content/Ge...any/1704040pdf
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I interpret the "ER" as meaning Externally Regulated. But that is just a guess.
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  #4  
Old 06-14-2018, 06:03 AM
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Bret, rewiring the B lead was next item on my list!

Joe, Thanks for the links. I am convinced that this was originally an externally regulated alternator with the F and N leads. But the original wiring worked flawlessly for over 20yrs and there was definitely no external regulator wired in. Short of removing the alternator and taking it to a repair shop, is there anyway to determine if it has been modified for internal regulation? I am trying to finish up my switch panel and need to install either a switch or CB for the field wire I assume if it is internally regulated?

Charles
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  #5  
Old 06-14-2018, 06:32 AM
Mich48041 Mich48041 is offline
 
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It doesn't matter if the regulator is internal or external. A fuse or circuit breaker should be installed to protect that circuit. There should also be a switch to shut the alternator off in case of smoke in the cockpit. Disconnecting the battery by turning off the master switch will not shut off the alternator because the field winding will still be powered by the alternator output. I would go ahead and install both a circuit breaker and switch, or a pull-able breaker.
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  #6  
Old 06-14-2018, 08:05 AM
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Mr Charles Mr Charles is offline
 
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Joe, are you saying that I should run a wire to the field terminal either way (internal or external regulation)? And that wire should be on a CB and switch, or pull-able breaker? That was what I was sorta planning to do until I ran into the problem of identifying for sure what I had. When you say a switch to shut off the alternator, is that referring to the field wire switch then? (I keep calling it field...I understand it is a "sense" wire if internally regulated) And when I rewire the B lead, if I wire it to the main buss, I assume I need to install a CB on it also? And if so, what size?
I have read and reread Nuckolls book as well as dozens of threads here, but my head is swimming with all the options! What about OV protection? Should I add that?
And please, is there a way short of removing the alternator and taking it in to do a test to see if it is truly been converted to internal regulation? Again, by all identification info I can gather, it looks like it was an externally regulated alternator, but has been working without an external regulator for 20+ yrs, so I don't see how it could do that UNLESS it has been modified?

Sorry for all the questions...your help is deeply appreciated!
Charles
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  #7  
Old 06-14-2018, 10:00 AM
Mich48041 Mich48041 is offline
 
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If internally regulated, then the alternator most likely it needs 12 volts to be enabled. The wire supplying that 12 volts should be protected by a fuse or circuit breaker. And there should be a way to shut it off.
If the alternator is externally regulated, then there still needs to be a wire supplying 12 volts to the regulator. And that wire needs to be protected and switched.
So in either case, there needs to be a circuit breaker and switch.
I do not know how to wire the F terminal. And I do not know of an easy way to test it.
As for the "B" lead, I would connect it to either the downstream side of the master contactor or the upstream side of the starter contactor. The "B" lead should be fused at the end closest to the battery. Use an ANL or Littlefuse Maxi rated at or slightly above the alternator output rating. The fuse should be located near the contactors. I would not run the "B" lead into the cockpit.
If the battery is Lithium, over-voltage protection is mandatory. Otherwise, over-voltage protection is optional but recommended.
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  #8  
Old 06-14-2018, 10:32 AM
444TX 444TX is offline
 
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I have seen the Hitachi IR alternators not shut off once excited. They only shut off by opening the "B" lead or shutting off the engine. A must check item.

GM
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  #9  
Old 06-14-2018, 10:59 AM
Mich48041 Mich48041 is offline
 
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Charles, there are lots of people who are knowledgeable about electrical systems on the AEROELECTRIC LIST. Try posting your question there.
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