best way to excite a delco altinator

international 606 · May 5, 2012

I am switching from a 3 wire alternator to a 1 wire and want to eliminate some wires. I was wanting to know if anybody has every wired there oil pressure sending unit into there alternator, this would excite the altinator when the oil pressure goes up. Sombody told me how to do this but forgot all the detail. Would be on a 444 diesel

thank you

pete 23 · May 5, 2012

A one wire alternator excites itself through internal connections in the regulator, no other wires required.

CLTX · May 5, 2012

You have to have an "On-Off" switch to break the current when the engine is not running, or you will drain the battery. I used a "make" pressure switch at the fuel filter on a Detroit 671 for years. You could do the same thing from the oil pressure line. Much better than a manual switch, which is easy to forget to turn off.
C. L.

old · May 5, 2012

Going to a 1 wire from a 3 wire why the heck you want to do a dumb thing like that??????????????? A 1 wire cost more to replace and you need to get the RPM up past max of most tractor engines to get on to excite and what you do not like 1 extra wire which is all that is there on a correct 3 wire set up that excites at start up RPM and to replace one is at most $50

John T · May 6, 2012

The "one wire" doesnt use any external excitation thats what its a "one wire" versus a 3 wire like the Delco 10SI family (which could use idiot light or oil pressure switch etc to excite and it can take a bit of RPM before it excites and there can possibly (depends on alternator and its wiring) be a very very teeny tiny current discharge when its just setting there.............

John T

LJD · May 6, 2012

A one-wire Delco 12SI when installed properly will self excite when the engine reaches 1400-2000 RPM. All depends on the size of the pulley on the alternator. All my tractors run faster then that. I never regarded it as an issue. If your tractors can't achieve that, you've got me wondering what the heck you've got?

Even a 3-wire has to spin 1600 RPM at the alternator to work, but what counts is engine RPM versus alternator RPM. All in the pulley ratio. Most cars and trucks run somewhere around 3 to 1 ratio. So if engine is idling at 800 RPM the alternator is spinning at 2400 RPM.

As to cost? I buy one-wire regulators new for $10 each. Same as I pay for three-wire regulators.

The ideal setup is a three-wire actually hooked up with three wires and using the sensing lead AT the battery. That is rarely done on tractors. Most posts I've seen here take the short-cut and actually use the "three-wire" hooked up with two wires to the tractor. When done like this the charge-voltage reading is taken at the alternator and does not account for voltage drop AT the battery.

John M · May 6, 2012

I dont think the factory one will work, if your planning on having both go through it. You can install another Normally Open oil pressure switch somewhere else to do what you want to do.

David G · May 6, 2012

Rub its belly

Sam#3 · May 6, 2012

About the same way you turn on a key. Lots of gentle caressing and soft mushy complimentary words.

Jon Hagen · May 6, 2012

One mistake a lot of folks make when installing a "1 wire delco alternator", is to buy a much higher output alternator than they need.

a 37 amp "1 wire" alternator will excite at about 1/2 the rpm of a 61 or 72 amp 1 wire alternator with all other componants except the stator being the same.
No sense putting a harder to excite 72 amp alternator on a tractor that originally had a 20 amp generator, where a 37 amp will more than meet the electrical needs. Only good reason to go larger is if you have an implement or added lighting that needs a lot of amps to operate.

best way to excite a delco altinator

international 606

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