MTFCA Forum

I have a very old Texas T Parts 12v Hitachi alternator that came on my 1915 Touring. It does not charge the battery. It has two wires leading from the rear, one from a post terminal and one from a spade terminal that appears to have a diode. Does anyone have one of these alternators? If so, I would like to know how it should be wired. Thanks. Barry

Barry

I'm not the guy with knowledge to answer your question, but only to ask:
Does your magneto work?
If it does, have you considered a Magneto-battery charger?

I cannot imagine a situation where an early T truly needs an automotive high amperage alternator to simply keep up a battery. The main draw would be headlights and an automotive 12V battery will take you through the night until you fall asleep at the wheel.

Just something to think about while you ponder your present dilemma

best of luck on the course you follow

and welcome to the Forum

Did you test the output of this unit? Is it actually dead or not producing enough current to keep the battery charged?
Common issue with alternators on T's is they dont kick on untill higher rpms.
I got a call from a guy that had just been in a parade & didnt have enough battery to start the car.
He wanted to know if the output could be upped. NOPE.

Like John said...
It would be easy just to take it to an alternator shop for testing. On the other hand alternators have an rpm threshold at which they start to produce voltage. some say 2000 rpm of the alternator not the car. . don't know about the Hitachi. so the pulley can make a difference. So you may not have met that threshold just puttering around like in parade.Also the battery may have issues prevnting it from holding a charge. Voltage is needed to charge battery (12.9v), current (amps) determine the time it takes to do it (trickle chargers is 2 amps, 10amps battery charger). What brand , type battery?

Thank you for the replies. I had been lean toward the magneto charger like Scott suggested. I already have one made up per John Regan's instructions. I was just hoping that if the alternator could be made to work, it would be a back up if the mag fails. We just drove the car 400+ miles on the Michigan Jamboree of T's at speeds that should have certainly caused the alternator to "kick in".
Incidentally, when I bought the car several years ago the mag did not work and I wasn't even sure there was one still in the car. It had obviously been set up to run on battery. I charged the mag in the car (figured I had nothing to lose) and it has run great on mag ever since.
Thanks again, Barry

Barry

re: mag recharge - brother you should play the lottery!

sounds like you have a happy, healthy car. You'll find a solution that works...and I just wanted to make sure you considered options outside of your specific request.

Gest of luck

BarryCogan wrote: ↑

Thu Aug 17, 2023 1:49 pm

Thank you for the replies. I had been lean toward the magneto charger like Scott suggested. I already have one made up per John Regan's instructions. I was just hoping that if the alternator could be made to work, it would be a back up if the mag fails. We just drove the car 400+ miles on the Michigan Jamboree of T's at speeds that should have certainly caused the alternator to "kick in".
Incidentally, when I bought the car several years ago the mag did not work and I wasn't even sure there was one still in the car. It had obviously been set up to run on battery. I charged the mag in the car (figured I had nothing to lose) and it has run great on mag ever since.
Thanks again, Barry

Barry,

Has it quit working, or has it never worked?

That yellow wire is brown in the earlier installation guides.

It powers the voltage regulator and must be turned off when the engine is not running or it will drain a battery overnight.

Jerry, I don't know. As you know, this was Dale McDermott's car and I don't know how he used it. I assume it must have worked because the mag was dead when I got it. I assume he had it set up to run exclusively on battery. The alternator is wired through an on/off switch and an ammeter. Jim's reply about the yellow wire is significant. I'm going to wire it directly to the battery and see if it charges, then figure out what to do from there.

The small wire may have gone to the idiot light, then to the ignition switch. I seem to remember having put a diode in a similar set up with an old GM alternator. That energized the alternator field and did not allow back flow to run the battery down when the vehicle wan't running.

As long as the wire is switch off when the engine isn't running, it should be OK.

Most old alternators used an external regulator which I assume controlled field current.

There should be a diode inside the alternator that would allow the battery to be directly wired to the terminal on the alternator.

That diode has often been destroyed by a heavy current battery charger.

A good test is to remove the wire from the terminal and measure the resistance between that terminal and the alternator case.

Then reversed the leads and do the same measurement again.

The numbers have to be at least 10 times larger from one way than the other way to have a good diode inside.

The early alternators with the external regulator had a small silver box, about 1 inch X 1 1/4 inches X 3/8th inches, that plugs into the back of the alternator.

Langs and Generator Joe in Ohio had them in stock about 20 years ago and they were about $40 each then.

It looks like that alternator has 2 connectors in the plug orifice in the alternator body. I'm guessing they are both ends of the field winding, and connect to the rotating field via the brushes. The power output of the alternator is produced in the stator windings, which are grounded at one end and connected through the internal diodes to the battery output terminal the other end. For the alternator to work, the field circuit would need to be energized, perhaps through the idiot light, thence to the ignition switch. Lacking a regulator, grounding the other end of the field circuit through a resistance, such as a brake light bulb, would probably allow it to function. Output would probably be limited. A "One wire" alternator, with no external regulation, probably energizes the field circuit internally, which may be why some internal regulated alternators have to reach a higher speed, or "build up" to begin to function. I put a one wire GM alternator on an old diesel tractor, and it worked, but it took its time to begin charging. That tractor has a big, low speed six cylinder engine and it has a large pulley on the alternator. I suspect that an externally regulated alternator would work better on that application.

If those two connections are at right angle to each other and flat, so one contact of a house accessory plug would fit and plug in, you are missing that little regulator box.

Generator Joe is Buckeye Auto Electric in Ohio.

Go to their website and look under Model “T” Parts to find this Alternator Regulator and it is $35.00.

One More Detail: It works on 6 Volt and 12 Volt Alternators.

That alternator only needs power on one terminal spade. Usually there is an F mark indicating field. I would crank the engine up. Put power on one terminal and check for output. If none then go to the other. That alternator has no built in regulator. If you need a regulator use a 60s Chrysler stand alone one. They are the simplest ones out there. The plug in reg pictured above works on Mitsubishi alternators, not Hitachi.

I am astonished at some of the comments on this thread. When Chrysler first started installing alternators (BTW - A Chrysler trademarked name) in 1960 the biggest advantage over the old DC generators was that the alternator would charge the battery when the engine was idling, something that the DC generator could not do. A standard 12V AC generator should work just fine on a Model T.

For what it's worth I just purchased a Delco Remy 6 volt alternator from Langs for my 26 Coupe. One wire to connect like the generator and it charges over 10Amps at idle.

Many modern cars (1960 onward) idle at 500 to 600 RPM or more and most alternator drives are overdriven. Most modern cars have a larger crankshaft pulley than can be fit on a Model T. The relatively small diameter Model T crankshaft pulley limits alternator RPM.

What txgoat says is true, but any competent machine shop can make you an AC generator pulley in any diameter you want. There are also numerous places that sell pulleys of various diameters. If you are going to drive the generator with a flat belt you are going to have to make a pulley anyways, if you are going to drive it with a V-belt, just make a bigger crank pulley. Pulley diameter should not be an unsolvable problem. Any automotive AC generator will put out far more current then any T that has an electrical system remotely approaching stock will need.

In this application, you can only make a pulley so small to speed up the alternator. Motor pulley is a fixed size.
Gear driven is fixed. You need to start with an alternator capable of sufficient charging within these fixed limits.
Claims are that the GM 1 wire unit will work.