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[Stu Jackson]

Alternator Regulator Wiring Diagrams

The only PURPOSE I originally had posting these diagrams was to show you how I used "record keeping" and these sketches to help me keep track and for identifying the wiring between a new regulator and alternator with the old wiring included.  It is one of many "wiring diagrams" I have developed for our boat.

{4/15/2012}  Battery sense wire since removed from alternator and run directly to the house bank: VERY important.  Note this also doesn't show the battery sense negative, as recommended by MS in his links below.

Once I ran the AO to the house bank, I removed the zap stop. - Stu

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In a later 2018 post about external regulation, Maine Sail made this point:

If you are using an external regulator those diagrams will not result in the performance you've paid for.. Correctly wiring the volt sensing circuit is critical to charging performance...
Here are a couple of articles that can help:
Alternators & Voltage Sensing (LINK)
Programming a Balmar Regulator (LINK)

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Point being that the negative sense has to be wired, too.  RTFM 

I never intended for these diagrams to be misinterpreted by anyone as a "How to Wire" YOUR regulator on YOUR boat.  That's up to you.  I wanted to show you how easy a wiring diagram can be to draw to keep track and record your work.  For example, the added battery sense wire note?  The regulator manual is very poor on differentiating between separate to the house bank or just off the back of the alternator.  Reading Maine Sail on sbo.com, way before he wrote these two articles, taught me that performance would be improved by doing so.  So I did. 

CLICK on each diagram for a clearer version

[Barry White]

Hi again Stu,
I spent some time this afternoon taking the cockpit panel off to further verify the "installed" version on our boat, and found that the wires to the ammeter are not in the #6 to 4 size, the orange is approx. a # 8, so there are a multiple of variations out there... the additional diagrams will be helpful..., thanks,

Barry

[Carolina Soul]

QUESTION:  I have wired my Alternator output directly to my House (primary) battery bank. It charges nicely when the engine is running,,,,no problems.  WIth the engine off, the Alternator pulls power from the Batteries, drains them and gets very hot (110 degrees and climbing).  Is this to be expected? or do I have a fault somewhere in my wiring. Some online  research revealed I may have diodes in the Alternator's Voltage Regulator that were stuck open.....but it has happened to three different Alternators.

[Stu Jackson]

QUESTION:  I have wired my Alternator output directly to my House (primary) battery bank. It charges nicely when the engine is running,,,,no problems.  WIth the engine off, the Alternator pulls power from the Batteries, drains them and gets very hot (110 degrees and climbing).  Is this to be expected? or do I have a fault somewhere in my wiring. Some online  research revealed I may have diodes in the Alternator's Voltage Regulator that were stuck open.....but it has happened to three different Alternators.

Yes, you have something wrong.  When the AO is routed directly to the house bank, the alternator is always "hot," but you shouldn't have the problem you are describing.  Why?  Because it is no different than having it wired the old way when the 1-2-B switch remains on.  Millions of skippers have rewired their boats this way and do not have the problem you described.

There are no diodes in voltage regulators, they exist only in the alternator.

Since this one is new to me, I do not have an answer.  I recommend you find a qualified marine electrician to help you out, especially since you say it's happened on more than one alternator.  That, in itself, says a lot.

Good luck and please let us know what you learn.

[Stu Jackson]

Only thing I can think of is:  have you disconnected/removed the wire between the AO and the starter solenoid?

[Ron Hill]

Stu & Guys : I had the similar thoughts of the problem describe by Carolina.  So I wired my battery "since wire" to the key switch.  That way when the key switch is OFF there is no "leakage".  I believe that I used a #14 gage wire.   

A thought

[Stu Jackson]

It is important to not confuse the alternator's regulator sense wire with the ignition power wire.

Internal regulators on the OEM alternators do not have sense wires to a battery bank.

[KWKloeber]

It is important to not confuse the alternator's regulator sense wire with the ignition power wire.

Internal regulators on the OEM alternators do not have sense wires to a battery bank.

Note that you can use the key switch as the sense by simply tapping into either the alt field excite wire (purple harness wire, (typically but not always terminating at a yellow wire on the alternator regulator) OR the fuel lift pump wire. They are redundant, both from the key switch “I” Terminix to the engine. (I’m not suggesting that’s a proper location to sense btty voltage.)

There was an alternator upgrade on the M-25 and XP (shown in the manual wiring schematics) that has external V sense on the internal regulator, so it’s not “universal” (ugggh) that our alts don’t have external V sense. Whether any of those engines/alternators made their way into the C34 I dunno, but I know that they exist on the 30s.