Delco alternator

MF294-4 · Jan 25, 2016

I am rewiring a 580B with a Delco SI 3 wire alternator. Someone has put a wire direct from the ignition switch to the alternator. It has worked like this for years. I found the resistor under the dash (75 ohm) and hooked it up. Now it has to get up to over 1/2 throttle to start charging. It rarely gets up to speed in normal operations. What I have read, is it needs more like a 10 ohm. I think the 75 was original though. Should I just forget about the resistor, get a different value, or put a diode in the line?

Janicholson · Jan 25, 2016

the amps are minimal in the wire, so a 10 to 15 ohm resistor wired across (parallel with) the existing resistor will be fine. It might have had an idiot light in that circuit. Jim

MF294-4 · Jan 25, 2016

No idiot light. I suppose the resistor might not be original.

Den N Ms · Jan 25, 2016

Mf294-4,Just put a diode inline and call it done.It will charge at startup without revving it up.

Mike(NEOhio) · Jan 25, 2016

I just went through this on my Oliver. No. 1 wire needs a resistor OR amp idiot light, not both. PO had it connected to the output stud and it would draw 50 milliamps with everything off. Lots of information on Delcos on line.

Hobo,NC · Jan 25, 2016

If it was wired to the ACC side of the switch it will continue to work for years why fudge with what works.

http://forums.yesterdaystractors.co...amp;postdays=0&postorder=asc&start=75

souNdguy · Jan 26, 2016

as Hobo said. if it was wired off the accy lug on the switch, it was already working FINE.. why fix it till it's broke???

Delco alternator

MF294-4

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Janicholson

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MF294-4

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Den N Ms

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Mike(NEOhio)

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Hobo,NC

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souNdguy

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