12v Conversion.. Where'd I go wrong?

Brad Gyde · May 9, 2010

Ok.. so a few weeks ago there was a post about 12v conversions. I asked a few questions since when I converted My massey Harris to a 12v, it would charge, but if it sat the battery was always dead after 3 or 4 days.

I wired it as it said.. 3 wire delco
Battery terminal of alt to + side of ammeter (as the generator was)
Terminal 2 jumped to batt terminal of alternator
Terminal 1 to coil side of ign switch (with a small "idiot light" in line (one side of light to ground, other side to the wire)

Once started, the light DOES NOT go out as it was said it would (and yes, I revved it up.. ammeter shows a charge) If I turn the key off, the tractor continues to run, until I unhook the #1 terminal. If I leave it unhooked, the alternator does not excite. It said to use either a light, a resistor, or a diode, and that I didn't need to use any combination.. just any one would work fine

What have I done wrong?? I don't consider myself dumb about this sort of thing.. and I followed the directions, so why is it not working like it should?

Thanks in advance,

Brad

tlak · May 9, 2010

I would compare it to 601-801 tractors, doesn't sound like your light is hooked up right. The light is resistance or as in the schematic a one way diode to kill out residue juice to stop it from running without the switch on.
601

Bob · May 9, 2010

Brad, you done GOOD!

If it is wired exactly as you as you state it is, your wiring is FINE.

Sounds like the ALTERNATOR itself has an internal problem, likely a bad diode trio and/or voltage regulator.

Brad Gyde · May 9, 2010

Thats what I was thinking too... But when I asked on the original post, I never got a answer.. so.. here I am

Brad

GA Dave · May 9, 2010

This diagram is for Ford 601 - 801 but should be close as to the alternator wiring. May help. David...............

Brad Gyde · May 9, 2010

Bob,

So the light should in fact be grounded? Right now, as a temporary, I have the #1 wire and the light crimped into the same connector, as I don't really know how else to splice it in where it'll work right.

I also have the wire temporarily hooked to the coil, but I don't see where that'd make a difference, as whether it is tied in there, or at the switch, they still make contact.

Bob · May 9, 2010

The "idiot lamp" needs to have two terminals, NEITHER of which is grounded. The light connects EXACTLY in the place of the diode shown in GA Dave's diagram. The choice to use the diode or the light is up to you.. functionally, they are DIRECT substitutes for each other.

<img src = "http://i167.photobucket.com/albums/u125/27Grainfield/424IH/Alternator%20Stuff/AlternatorHarnesssd.jpg">

<img src = "http://i167.photobucket.com/albums/u125/27Grainfield/424IH/Alternator%20Stuff/AlternatorHarness31.jpg">

Bob · May 9, 2010

Brad, I stupidly missed the "GROUNDED" part in your first post. My reply to your later post is correct.

Brad Gyde · May 9, 2010

Bob

THANK YOU so very much.. The pictures helped alot.. as did the previous diagrams..

I will switch it to the light "inline" as opposed to grounded tomorrow after work and see if it fixes it.

I asked the grounding question before, but never got an answer. Right now, I'm temporarily "mocking" it up, as this week I'm going to disassemble for painting, and am going to make a new wiring harness upon reassembly.. Just want to be sure it's all gonna work when I put it all back together.

Thanks again..

Brad

Bob · May 9, 2010

The way you actually had it connected explains why it did NOT go out while ignition was "ON", HOWEVER, I don't think it explains a battery drain while the ignition was "off".

If the battery drain still happens, the next time you shut it down disconnect ALL wires from the alternator (tape 'em up to prevent a short) and see if that stops the battery drain. If it does, have the alternator tested.

JMOR · May 9, 2010

Brad, the advice you have received will fix the "continues to run" and the light behavior problem, but I see nothing here that should be expected to fix your "battery goes dead in 3 or 4 days". Sorry.

Brad Gyde · May 9, 2010

Sorry..

I should have mentioned that I haven't had a drain since I mocked it up this way. Before I did this, I wired it up when I was about 17, and I think it was cause I had the excite wire hooked to where it was always hot (what can I say, I did it myself with LITTLE or NO help back then, and didn't have the net then either..).. But I can't remember exactly how I had it before, as I changed the wiring to basically what I have now (minus the light) about 6 years ago, and the tractor has been in the corner ever since.. In fact, Friday night was the FIRST time the tractor has been started since getting all new valves, guides, coil, wires, head gasket, thermostat etc.. and that too was about 6 years ago.

I decided this winter that come spring, I was going to pull the tractor out and finish painting it, as I have had a pile of painted parts in the basement for 6 years now.. And always said I wouldn't get married till the first tractor was done.. and the gf keeps pushing the marriage issue.. so I guess I better finish it up LOL

Brad

cuttman · May 10, 2010

Bob
I am having same problems as Brad except I have a farmall B. It only has a voltmeter and a toggle switch instead of a regular starter switch. Do I wire the number 1 terminal to the voltmeter first or not. I understand the 10 guage wire goes to battery. I didn't know this was so complicated??? I have to jump start it everytime I want to use it.

Bob · May 10, 2010

The alternator's #1 terminal does NOT go to the voltmeter.

It MUST be connected to a power source that gets switched "off" at engine shutdown. It needs an "idiot light", a resistor or a diode in the circuit to limit current feeding OUT of the #1 terminal.

The purpose of this connection is to supply field current to "excite" the alternator so it begins to charge at startup.

There are many ways to do this... power it from the "load side" of the ignition switch, use a momentary contact pushbutton switch, an oil pressure switch, or even a toggle switch that the operator needs to remember to shut off any time the engine is not running.

cuttman · May 10, 2010

So if I understand you right, I run the #1 terminal to a toggle switch then to the voltmeter and then where

Bob · May 11, 2010

NO Voltmeter on #1.

As I said before, the power to #1 needs to come from a source that is only "HOT" when the tractor is running/ignition "ON" AND it needs to have an "idiot light", diode, or resistor in-line to limit the backfeeding of current OUT of the #1 terminal.

12v Conversion.. Where'd I go wrong?

Brad Gyde

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