Single Wire Alternator Update

5 Forward · Mar 18, 2013

First I would like to say thanks to all who responded to my alternator problem and helping me find the tac drive gear.
It appears the alternator overcharged and smoked the regulator. It quit charging so I have replaced the single wire with the 3 wire set up. The single wire was thirty bucks more plus I have a life time warranty on the new one.

Janicholson · Mar 18, 2013

Single wire systems do work for some applications. There have been more issues with them by far compared with the 3 wire. The 3 wire is very close to the same way they work in a car or truck. They are so reliable we forget they are even there. Jim

David G · Mar 19, 2013

I am not a fan of the single wire, I think they drain the battery when left for a long time and require RPMs after starting to charge.

dej(Jed) · Mar 19, 2013

(quoted from post at 15:30:16 03/18/13) First I would like to say thanks to all who responded to my alternator problem and helping me find the tac drive gear.
It appears the alternator overcharged and smoked the regulator. It quit charging so I have replaced the single wire with the 3 wire set up. The single wire was thirty bucks more plus I have a life time warranty on the new one.

I have done several single wire conversions and never had a problem. simply switch the amp gauge flow and you are good to go.

Bob M · Mar 19, 2013

Jim - My experience with 1-wire alternators has been mixed. Some worked fine. A few however would drain a battery in just a few days. Seems it's a function of the quality of the internal regulators installed in the 1-wire units.

Edchainsaw · Mar 20, 2013

I am going to put an Alternator on my B but if I put the 3wire will I need to put a switch on for the field or how will I turn on the alt... (i like the mag and am keeping it)

Jon Hagen · Mar 20, 2013

Unless their is still some weird cobbled up stuff out there, the standard "1 wire" alternator built in the last 20 years, is simply a stock SI series Delco alternator with a self exciting regular substituted for the stock 3 wire regulator. These "1 wire" units do not have anything connected to either the #1 excite terminal or the #2 sense regulator terminal, nor do they have any internal connection to the battery, as that connection is totally blocked by the rectifier assy, so they cannot run down the battery.
Many years ago(30+) GM sold a 1 wire alternator setup that DID have an extra internal lead from the regulator to the alternator output stud, that one would slowly discharge the battery. You can identify those by the black plastic plug in the regulator socket, topped by the red voltage adjustment cap that can be installed 4 ways to adjust output voltage.
I remember reading of another conversion, or more correctly a perversion that added a resistor between the battery stud and the regulator excite connection, to make a stock 3 wire regulator excite at lower rpm and act as a crude 1 wire alternator. I thankfully have not seen one of those for a long time and am glad, as those things are likely what gave all correctly done "1 wire" alternators the undeserved reputation of being a "battery killer."

Jon Hagen · Mar 20, 2013

Two ways of "exciting" the alternator on a mag equipped tractor work pretty well.
1 way is to replace the mag kill switch with a DPDT toggle switch. You wire one side of the switch so it grounds the mag when the bat handle is down and opens the battery to excite (#1) alternator wire with the other side of the switch. When the switch bat handle is up, it ungrounds the mag and connects the alt excite wire to 12V power.

2 Another way is to put a normally open, two terminal oil pressure switch in an engine oil pressure port so it connects the alt (#1) excite wire to battery power only when the engine is running and has oil pressure.
With either setup, you do not need to turn on / off another switch to excite the alternator, so little chance of forgetting and killing the battery.

Jon Hagen · Mar 20, 2013

Another "1 wire" alternator problem being that it takes too much rpm to exite it, is caused by folks buying too high an output "1 wire" alternator. Many parts stores stock only the 61 or 72 amp "1 wire" alternators. Most tractors with only lights and ignition load do not need more than a 37 amp alternator, yet install a 72 amp, because that is what the parts store had in stock.
My experience is that a 37 amp "1 wire" alternator will self excite at 1/2 the rpm of a 72 amp unit, usually no more than fast idle on most tractors.

GRAPE-DRANK · Mar 22, 2013

Add me to the list of someone having trouble with the single wire alternator. It runs the tractor just fine, but it IS NOT charging my battery. Mine is brand new, 60 amp. I know it works,but its killing the battery.

GRAPE-DRANK · Mar 22, 2013

If I get a battery disconnect for the negative battery post will that solve my problem?

JMOR · Mar 23, 2013

(quoted from post at 19:55:48 03/20/13) Unless their is still some weird cobbled up stuff out there, the standard "1 wire" alternator built in the last 20 years, is simply a stock SI series Delco alternator with a self exciting regular substituted for the stock 3 wire regulator. These "1 wire" units do not have anything connected to either the #1 excite terminal or the #2 sense regulator terminal, nor do they have any internal connection to the battery, as that connection is totally blocked by the rectifier assy, so they cannot run down the battery.
Many years ago(30+) GM sold a 1 wire alternator setup that DID have an extra internal lead from the regulator to the alternator output stud, that one would slowly discharge the battery. You can identify those by the black plastic plug in the regulator socket, topped by the red voltage adjustment cap that can be installed 4 ways to adjust output voltage.
I remember reading of another conversion, or more correctly a perversion that added a resistor between the battery stud and the regulator excite connection, to make a stock 3 wire regulator excite at lower rpm and act as a crude 1 wire alternator. I thankfully have not seen one of those for a long time and am glad, as those things are likely what gave all correctly done "1 wire" alternators the undeserved reputation of being a "battery killer."

on, you said, " nor do they have any internal connection to the battery, as that connection is totally blocked by the rectifier assy, so they cannot run down the battery. " Given that such is the case, what is regulator sensing & where? The diode trio output? Only external connections alt to reg are trio, brush, gnd. Ever open one up to see where they are sensing? THX

Jon Hagen · Mar 29, 2013

I would say you are correct. The only electrical connection between stator voltage and the "1 wire" regulator is through the diode trio.

Single Wire Alternator Update

5 Forward

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Janicholson

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David G

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dej(Jed)

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Bob M

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Edchainsaw

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Jon Hagen

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Jon Hagen

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Jon Hagen

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GRAPE-DRANK

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GRAPE-DRANK

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JMOR

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Jon Hagen

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