Getting a Delco Alternator Excited

KCTractors · Apr 12, 2012

Every 12 volt conversion I did with the Delco alternator, I have to rave up the rpm"s to get it excited. I am using the idiot light method with the exciter wire. I am using 14 gauge wire from alternator to the ignition switch. I was thinking that maybe, I am using to heavy of wire.
Would help if I put a diode in line with light or use lighter gauge wire. Any suggestions?

rvirgil_KS · Apr 12, 2012

Rev up to start is normal with "one wire" Delco

14 gauge wire is ok for idiot light.

#2 on plug connects with short wire to big output stud
#1 goes to one side of idiot light, other side of light to switched side of ignition switch.

Owen Aaland · Apr 12, 2012

The amount of voltage at the #1 terminal will determine how fast the alternator must turn before it begins to charge.

A diode in line (series) with the light will not make any difference since the light bulb is the resistance that lowers the voltage at the alternator. If you wire the diode in parallel with the light the light will not turn on since the current will flow though the diode rather than the bulb.

You need a minimum of about 6 volts to get the alternator to start at a lower rpm. You can use a resister wired in parallel with the light to increase the voltage available at the #1 terminal. The resistor will however cut down on the brightness of the light.

Jon Hagen · Apr 12, 2012

Add a second idiot light, wired in parallel with the original(GM did that factory stock for years).(The extra light can be hidden.

Using a diode alone in the excite wire may excite the alternator faster than the charge light, but then you lose your charge indicator light.

Using lighter wire or a diode inline with the idiot light will actually make the situation worse, as either will drop the voltage to the #1 alt terminal.

Use as small a pulley on the alternator as possible to help it excite at lower rpm.

Anonymous-0 · Apr 12, 2012

Stroke IT !, worx at my house! ,, sorry to make lite and lafs ,... but i see you got qualified answers, and when i saw the titled post ,,, the Bud-wiser in Me Couldnt help poking fun , for a smile .... g-nite jh

old · Apr 12, 2012

That is why I use a diode in a 3 wire set up. Full voltage to it but only a one way circuit. It starts to charge at start up and works very well. I use radio shack part #276-1661

oldironman · Apr 13, 2012

Change the bulb in the dash lite to one with a lower resitance. If it is a LED light replace with a old type one. We had the same thing with a wood chipper that had a LED light. Changed the bulb and all was fine.

Geo-TH,In · Apr 13, 2012

I have 2 newer delco's and both have to be reved up to get excited. The older ones would put out right away.

I'm convinced it's just the way they are build. They need 12-1500 rpm's to wake up. After that you can slow down the engine and they will continue to work. Just get used to it.

Anonymous-0 · Apr 13, 2012

(quoted from post at 18:48:11 04/12/12) Every 12 volt conversion I did with the Delco alternator, I have to rave up the rpm"s to get it excited. I am using the idiot light method with the exciter wire. I am using 14 gauge wire from alternator to the ignition switch. I was thinking that maybe, I am using to heavy of wire.
Would help if I put a diode in line with light or use lighter gauge wire. Any suggestions?

If it's like a bunch of the folks on here, just crack a couple jokes about texas or west virginia.maybe a couple about organized religion, tellem traffic cameras are a good idea, or just pick your nose and tellem about it.
It'll be workin in no time flat :shock:

soder33 · Apr 13, 2012

You must be using a one wire Delco. A one wire alternator has a turn on point (sometimes called cut in, which is typically 1200 engine RPMs). This is the speed where the internal sense circuitry connects the battery to the voltage regulator, thereby turning the alternator on. Once the voltage regulator turns on, the alternator will remain on and charging until the engine comes to a complete stop. If the engine idle speed and pulley ratio combination do not allow the alternator to come up to this point during starting, the engine will have to be revved up to turn the one wire alternator on.

Sometimes, you can eliminate the revving up on a one wire.

Some one wire alternators can be hooked up as a three wire. The one-wire alternators have a black plug cover on the side of the alternator. This can be removed and the GM or aftermarket two-spade wiring harness can be plugged in for three-wire operation. Now the alternator will not be dependent on reaching a certain turn on RPM. Some research will need to be done to see which one wire VR's can be used as a 3 wire.

buickanddeere · Apr 13, 2012

Too heavy wire ??? Nope. What do you really have there as an alternator regulator configaration and which terminal numbers are connected to where?

Bspauld · Apr 13, 2012

I didnt know about using an idoit light and always used a key switch with an Acc side on it, Hooked the exciter wire to that and never had a problem. I have a one wire on my super A that I have to blip the throttle to get it going but I need to put a smaller pulley on the alt.to make it spin faster

Chip812 · Apr 13, 2012

I've always wired mine straight to the 'ON' switch (i.e. no light)... I do however have a voltage meter (but not wired in that circuit) that will tell me if the alternator is working or not... No issues (so far) that I'm aware of...
8)

Jon Hagen · Apr 13, 2012

Too many folks oversize a 1 or 3 wire alternator.

The small 37 amp will excite at much lower excite voltage and rpm than a 61 or 72 amp alternator.

JMOR · Apr 13, 2012

(quoted from post at 11:25:09 04/13/12) Too many folks oversize a 1 or 3 wire alternator.

The small 37 amp will excite at much lower excite voltage and rpm than a 61 or 72 amp alternator.

on, you have already mentioned the parallel idiot lights and that is useful. The single 194 or other similar (~0.2 to 0.3 amp) bulbs are so marginal, that if it were not for the cold filament surge, many alt/regs wouldn't ever excite, as I have learned from bench testing (motor belted to alt & meters used to measure excite current needed for kick-in). When the 10-SI was first commonly used (~1971-72), GM had a 10 Ohm, 6.25 Watt resistor in parallel with the bulb. Huge difference in excite current ( 1.0 amp instead of 0.3 amp).

KCTractors · Apr 13, 2012

A follow up, I just finished converting a 9N Ford and I used a diode instead of the idiot light. The alternator excites right away. I think I'm going to change out the lights and go with the diodes and see what happens. Thanks for all the replies!

Getting a Delco Alternator Excited

KCTractors

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old

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