The Stovebolt Site Forums The Shop Area The Electrical Bay 3-wire alternator conversion

I recently converted (on a '50 3100, 12 volt) my one-wire alternator to three-wire per instructions I read here and on the internet (connect one of the prongs of the internal regulator to the battery bolt on the alternator, the other regulator prong to an alt. dash light).

However, I still have to GREATLY rev the engine to get the alternator to turn on. Of course, a 3-wire hook-up is supposed to turn on the alternator immediately, without the engine rev.

Any suggestions on why I still have to rev the engine to turn on the alternator? And, yes, the battery connection is connected correctly to the internal regulator.

Thanks in advance for your help/suggestions.

Regards,
Richard

Could you have the wrong wires hooked up on the regulator. Does the dash light come on when you turn the key on & go off when it starts charging?

Does the dash light come on with the key turned on but engine not running? If not it may not be hooked up correctly. I have done a lot of these conversions on Chevelles. Later

Dave

I must have something hooked up wrong, I just can't figure out what. When I have the "light" wire (#2 spade) from the alternator hooked up to the ignition, it doesn't require that the key be turned "on" for power to go to the starter/accessories. It essentially bipasses the need for a key. AND the alternator light stays on...it's my understanding that when the alternator turns on (with the ignition), the light is supposed to go off. Also, I'm still having to rev the engine to get the alternator to turn on.

I'm stumped...I've reversed the wires on the alternator, to no avail.

If I'm not mistaken, it's the resistance of the bulb to ground that starts the charging. I would go to M.A.D. enterprises website and check your wiring. You shouldn't have to rev it to charge. They start charging at like 4-600 rpm. Later

Dave

The exciter wire that you connected to the dash light wire needs to then be connected to the positive post of the ignition coil. When you are done both the dash light wire and the exciter wire will be connected together then attached to the (+) terminal of the coil.

The exciter wire has the job of using battery voltage to excite the fields inside of the alternator so when the engine starts the alternator will begin charging regardless of the idle speed. In your case the exciter wire is not receiving any battery current so it cannot excite the fields and make the alternator charge when the engine starts.

When the alternator spins fast enough it will release stored magnatism from the rotor on its own and begin charging (this is how a one wire alternator works and is why you have to rev up a one wire alternator to make it engage and start charging).... as you have experienced.

After all of this...If the engine fails to stop running when you turn the key off then you need a DA Plug which will make the alternator charge when it is suposed to and the engine will shut off with the key as it did before. Fifth Avenue has the DA Plugs for sale. Then you will live happily ever after. Thanks Randy

I believe that the one wire alternators use a different internal regulator than the standard three wire versions. I bought one of the one wire regulators to convert a standard alternator to a one wire. You may want to install the standard regulator in your alternator.

maybe it's the Alternator itself... does the problem still happen with other 3 wire alts?

thanks bowtie
what a nice site -- M.A.D. Electrical lots of interesting items.
I just love learning all kinds of tipster stuff on this great 'bolters website'

and thanks to anyone who has let us tips
cheers
jim

Set up a three wire alternator ... really four.
What I see in one of my hotrod wiring books is,
IF you have an ammeter and External regulator.

One wire (8 or 10 ga) from the HOT+ 12V starter ''big battery wire'' terminal to the + post side of the ammeter.
Neg. side of ammeter to: both 'Battery post' @ key switch and 'BAT' post of alternator.
. The ext. voltage regulator has 4 posts: F, #2, #3, #4 .
'F' on alternator to 'F' on regulator.
'R' on alternator to #2 on regulator.
'IGN' of key switch to #3 on regulator.
Idiot lamp on dash to #4 of regulator and 'IGN' of key switch.
This way your ammeter tells you the draw and when it charges. The idiot lamp does not come 'on' until you turn on the key because it gets it's power through the key switch when turned on. The other side of the idiot lamp goes to #4 post @ voltage regulator to complete it's circuit. Always (upgrade) use a larger gauge wire to the battery from the alt'r 'BAT' terminal. Note: gauge depends on location of battery.
Make ALL connections solid or solder & heat shrink. Remove those cheap plastic colored things off solderless terminals. Is that about right.... ?

SO guys my querrie is:

What IF you don't have an ammeter...but do have a voltmeter.
Run the 8 or 10 gauge wire from the starter HOT +12v to the 'BAT' on the alternator...directly to the 'BAT' of the alternator???
Run the voltmeter off the 'IGN' of the key switch post?
Run a large gauge wire from the starter HOT +12V terminal to the 'BAT' of the ignition switch?
Leave everything else as is.

I assuming that if you have an internal regulator system that the same applies only the regulator is built into the alternator and no mounting of the ext. regulator is needed??

[img]http://www.rowand.net/Shop/Tech/images/AlternatorWiringOverview-1974to1985Buick_small.jpg[/img]
This is the best and simplest drawing around that shows how GM wired their alternators. GM did not run a wire from pin #2 directly to the alternator "Battery" post and I'm guessing you wish to achieved the same results they have. The loop up to the junction block and back provides the voltage sensing needed to regulate the voltage properly. MAD Electrical does a much better job of explaining this.
Voltage Sensing

A diode from pin #2 to "Bat" is claimed to achieve this, but I've tried a couple of diodes with no success.

The resistor shown is actually a resistance wire that goes from the firewall plug to the ignition switch. I'm not sure, but that may be why they they have it on its own switch connection. You can use the one single switch connection(IGN) for the light and put a 10 ohm resistor in parallel, across the light. I have seen some cases where they worked without the resistor, but get a 10 ohm 10 W wire wound resistor and you'll be happy.

If you're interested, note the similarities in this wiring.
[img]http://www.rowand.net/Shop/Tech/images/AlternatorWiringOverview-1963to1972Buick_small.jpg[/img]