Alternator - 1 wire vs 3 wire

I've been using a three wire setup for 35+ years, before we knew much about single wire. Worked great all that time. The nice thing is it starts charging a low RPM.

JB
 
Jerry in Shasta said:
The nice thing is it starts charging a low RPM.

JB
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That's the biggest advantage of the three wire. Another is you can use a charge indicator light (idiot light) with a three wire. I prefer a three wire alternators on my other cars.

The only reason my "A" is a one wire was on it when I bought it.
 
Jerry, another good thing about a 3 wire alt other than it starts charging at idle, it will not keep the alt excited once the key is turned off, a one wire, will and has failed to break the connect between the alt and batt, which will cause a dead batt if left on all nite not a guess or hear say, it has happened to me and several other club members, it prompted us to send out a news letter warning about the problem with the one wire
 
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I have 8 cars and some have 1 wire and some have 3 wire. I have never had a problem with any of them.
Anyone with a 1-wire who has a problem with the battery running down at night has a defective regulator, and should make a warranty claim. These alternators were clearly not designed to discharge your battery at night.

As for other aspects of the link, many of us would prefer to keep the ammeter because it can be so useful for trouble shooting. Replacing it with an idiot light, not so much

To each his own. From reading past comments on this on-going debate (third in line after oil and antifreeze), I doubt anyone will change their mind because of the link:)
 

I've helped a lot of guys with one wire alternators, although I'd never use one based on the 10/12SI design.

Here's a three-wire Denso in my 160B. My 40B has a stock genny. I experience the best of both worlds.
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Hi Guys, There is another advantage to the three-wire connection for alternators. If you have any electronic equipment hooked up to your electrical system, whether it is an ignition system, GPS or other device, these instruments do not like "voltage surges" like the ones that occur when a one-wire alternator comes on line at a higher engine rpm. The three-wire alternator comes on line when the ignition switch is turned on and when the engine has not yet been cranked, so it enters the electrical system "softly" and without power surges. Wire one provides the charging current, wire two provides the exciter to the field, and wire three monitors the current output at any point the installer determines on the wiring schematic. Not a bad system, really...
 
I have been running 1 wire alt's on 1931 tudor and 29 roadster, since August 2000. I put about 1100 miles per month on tudor and 500 miles per month on roadster. I have never had a problem at all with either alternator. YES, at start up neither show charge but you don't have to rev it up or anything else , simply when you are ready to drive away or use the gas in any way magically [ dugh] THE ALT. STARTS CHARGING. GUYS, STOP FREAKING OUT OVER IT NOT SHOWING CHARGE BEFORE YOU PULL OFF . have fun modelAtony tony white Lafayette, LA
 
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I'm with MikeK. The Denso is a better choice. I have posted this before; if you are going to use a 10SI use the VR that is turned on with stator (ac) voltage. As to surges they don't exceed their set point on start up best I know and the battery is very nice filter.
I like the 12190. 40 amps
 

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JackA send me your email and will send you the instructions and diagram of how to wire up the three wire alternator a lot cheaper than that kit. Took the kit apart and found out how it was made. Was able to make the kit for a couple of dollars for the DA plug, rest of parts had on hand. The three wire has the advantage of charging immediately. You do have to remember to disconnect the voltage from the battery to the alternator when you put the A away for any length of time as the alternator draws a small amount of current for the field windings when the ignition is off. The Model A ignition system is not like modern cars where the key turns most things off. The Model A key only disconnects the points from the coil. Everything else is hot and the cut out isolates the generator from the battery so it will not motor. My email is jrelliott42@gmail.com
 
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