Alternator on a cub

Never seen this kind of plug before, will it work on any alternator? Makes it a 'one wire'?

No. It will work for as long as the vehicle is operated every day. A typical OEM alternator, of most makes, drains an excite current of 80 to 200 milliamps. Some new replacement alternators are one wire active even if sold as 3 wire. The #1 terminal needs to be switched on the excite the alternator and avoid drain. One wire units that work have regulators that drain with just a few milliamps, and can be a month or more between running. Jim

Hooked up that way will do 2 things.
#1 drain the battery
#2 burn the alternator out
Why you ask well the excite circuit will stay on till the battery is dead and or till the excite circuit burns out and maybe even the tractor burn up

One reason I have a master cutoff switch on my old stuff.
Can't drain the battery.

I always unhook the negative battery cable on all my tractors, every night. Still an issue?

Just wrong. no issue if disconnected. If sold it becomes an issue that is easy to avoid with an excite switch, or diode, or small lamp, or 10 ohm resistor, or an oil pressure switch if it has a Mag. Jim

One of those small wires is the sensing wire.
It measures the voltage deep in the wire system to tell the alternator when to cut off and on.
By being buried deep in the system it accounts for voltage drop over the system.
Since a old tractor has a very small wiring system hooked to the charge lug like it is works fine.

The other small wire is the excite wire.
Power is supplied to this terminal at start up to excite the alternator and start it to charging.
Once charging the alternator sends power back out this wire.
It is what makes the dash light go out. Equal power on both sides of the light so no current flow.
Problem is feedback of power into the system on this wire will supply power to the ignition coil when the key is turned off.
Hence the reason you need a dash light or diode in this wire.
Exception would be a motor that does not require battery power to run such as a diesel motor.
This wire is usually hooked to the key switch also to disconnect power preventing it from draining the battery over time.

So if the motor is such as you can turn it off such as a diesel and you disconnect the battery after each use that system will work just fine.

Unhooking the battery only works if you do so every time you shut it down other wise the excite circuit will have power on it and can cause the alternator to over heat and also drain battery power

It will charge the battery. But will also discharge the battery when not running. The excite wire needs to go to the ignition switch with a diode added.

I may be missing something but, the two white wires go to the brushes in the alternator exciter circuit? Why are they both fed from the same terminal? Surely one should be power and one earth.

Brian.

To answer the original question. The "plug" is just a clone of the connectors used on the wiring harness for the 10SI and similar Delco alternators, it will not work on all alternators. They are available at most parts stores as replacements for damaged or missing connectors, instead of using plain, individual spade terminal connectors. A proper part for harness connections when converting to Delco 3 wire internal regulated alternators. In the picture it is shown improperly wired, as pointed out in other posts.



This post was edited by Jim.ME on 12/05/2021 at 06:04 am.

GP,
will it work?

I think this is how Autozone tests alternators.

Not the recommended way to use an alternator.

The Voltage regulator most likely drains the battery.

I don't remember which wire I connect an idiot light to.
I prefer Idiot light to a diode because my Farmall used a Magneto. To kill the engine you push in on a switch and short out the Mag. If I don't turn off the switch the alternator and inline gas solenoid will drain the battery.


I made my own wiring harness for Jubilee. I wired it the same way.

The carburetors on ford and farmall both drip when not running.
I have too many senior moments to remember to turn gas off, so I use 12v inline
gas solenoids of both tractors. Terramites came with solenoids. I've added solenoids to any mower that drips gas..

(quoted from post at 21:50:48 12/04/21) I always unhook the negative battery cable on all my tractors, every night. Still an issue?

Click to expand...

WHY? If wired right , not an issue. Do you unhook the battery cable on your cars and trucks?

On a Delco, one (the #1 marked spade in the edge connector) goes to a switched voltage source (often the key or ignition switch for convenience) usually through a small filament lamp that is displayed on the dash panel. inside the alt. it connects to electronics in the internal voltage regulator. When the key is turned on but not started, the internal regulator acts electronically like a ground, causing the light to shine. When the engine is started, the alternator makes enough residual voltage to cause that terminal to have battery voltage. Because there is voltage on both sides of the filament, the light goes out. The regulator then powers the brushes creating charging. The #2 terminal in that connector is a sensing connection that (should be) connected to the battery Positive terminal or close to it. This causes the regulator to produce the 14.2 or so volts that are regulated. In this install, the #2 wire can be placed at alt output because the charge wiring is short and conducts well allowing adequate regulation. If there is no lamp in the #1 spade connector wiring, it must have a diode or 10 ohm resistor to prevent that terminals run voltage, mentioned above, from causing the ignition to be energized even with the key or switch off. It can provide 4 or 5 amps that would back feed the coil and not let the tractor shut off. The supplied excite voltage does not need to be continuous, so some use a push button to start the alternator charging every time the tractor is started. Some use a oil pressure switch with 2 terminals one hot one to the #1 spade. when there is oil pressure the alternator starts charging. when stopped, the excite voltage goes away. If that alternator is wired in the way shown, the alternator stays in an on-ready-to-charge state and will run down the battery over a short or longer time window. Jim

Mine didn't work.

You may have a one wire alternator. Pull the plug and look. Are the two spade terminals connected with a jumper that is part of the spade terminals similar to what you would see on a household duplex outlet? You could also take the back off the alternator and post a photo of the regulator. A one wire regulator looks different and the internal wiring is slightly different from the 3 wire. A photo will tell for sure.

The plug in the picture does not, by itself, make a one wire alternator but that joined plug is often used in a real one wire conversion. The regulator is different and there is more to it than just joining the sense and excite terminals to the B+. That is also different from making a one wire alternator by just leaving off the excite wire. Different internals, different regulator and some other wiring. It would be interesting to know what you have if you have the time.