The Stovebolt Site Forums The Shop Area The Electrical Bay Generator to alternator conversion

1. Are you saying the exciter wire is NOT connected to the ignition switch but is connected to the fuse panel "ACC" fuse/terminal?
2. Is your ignition switch THE original, an original style replacement or a universal?
3. When you added the bypass wire, was the bulb still involved? Installed in it's socket? Still "In the circuit", albeit in parallel ?

I am only asking these questions to be sure I understand and not to annoy you. Your experiment is important.

1. Exciter wire is connected to the fuse panel circuit that is powered by the ACC terminal on the ignition switch. Not connected physically to the switch. Electrically the same as if connected directly to the switch ACC terminal.

2. My truck is a 59 originally a 6 cylinder. This switch is from a few years later which had electric solenoid start and ACC connections.

3. Bulb removed, inserted a metal blade in its place. The bulb/socket is a 194 side marker type bulb. Maybe still had some resistance?

Mark

The issue is feedback. Something feeding voltage to the coil. Your test is valuable. But most folks are following the "instruction" to run the wire to ignition "ON".

So without knowing what actual switch you have, what harness you have and if you wired it per instructions or wired to the ACC fuse yourself, the bottom line is that it's impossible to say if you have a feedback path when switch is off, at this point. I think I said each case is different and some who have a direct wire, no bulb, have run-on and some don't.

There are at least two "original" solenoid switches available. The ACC function is different for each.

You may have proven something and may not. You did prove you don't need a bulb. Glad you are keeping it for a warning.

I thought you added a bypass wire, sorry, I see you just put in a piece of metal into the wedge base style socket.

My truck does not have a feedback path when the switch is off because of using the ACC connection for the exciter wire. My ACC terminal is not common with the IGN terminal when the switch is off. I think the reason instructions would say run the wire to ignition "ON" is so that one could use the radio or other low current accessories without the motor running and without draining the battery through the biasing circuit of the alternator. I was not worried about that and used the ACC connection to prevent feedback to the coil. With the side marker bulb in series the drain is very small and has never been a problem.

Mark

Keep in mind the ACC fuse in a new harness with prewired fuse box has nothing to do with the old ACC terminal on a 55-59 solenoid ignition switch or a new ignition switch ACC terminal.

Did your harness have instructions for an exciter wire? If so, where did they have it wired?

"It is a custom harness and the exciter wire is connected to the ACC side of the fuse panel so it is separate from the ignition hot side"
There is no "ACC side" on the fuse panel. There is an ACC fuse, not normally used. There are fuses that are "always hot" and there are fuses that are switched to be hot by the ignition switch. The ACC is one of the fuses that is switched. It is no different than the other switched fuses. It's just an extra fuse for choke or some odd ball thing. I am going by the assumption that a run-on is a miswire. Due to misunderstanding of the ignition and such. A starter with no "R" terminal or something like that. Folks trying to make old ignition parts work in a 12V conversion with a new 3 wire alternator and new harness. It can be confusing. I do want to say that if a bulb or a diode or a resistor fixes it, do that.

That's why it is hard to figure out why some no bulb folks have run on and some don't. That's all I'm trying to figure out. You can be the answer. You are so close. If you could transfer that "ACC" wire to IGN ON, with blade in the socket, you could prove something. Then if it runs-on you could put bulb in and try that. All you need is an alligator clip on an existing wire to the coil positive or ballast resistor, so as to stop motor in case.

OR...........one of these days I will find someone with a 3 wire 10si, no bulb, with run-on who is willing to try a few things. Now that I'm obsessed.

It's all interesting. I will do some more checking tomorrow. Bear in mind that my harness is designed by me and is wired according to the instructions (written by me as well). Its a Painless fuse panel that I modified to suit but thats about as close to off-the-shelf as it gets.

Mark

Holy cow, thought you went to bed and I was still typing/editing, Sorry Mark.

OK I understand what you did. A person could be an electrical engineer or an electrician...... None of that helps much with old truck wiring. Well, maybe a little. Nice to see you getting deep. Super good.

I really hope you do it tomorrow. Be sure to make the test pure. Thank you very much.

In an effort to make the test a little more "pure" this is the procedure I used.

I removed my original idiot light bulb so my harness exciter wire is effectively not connected to the alternator.

A typical old truck wiring harness would have the ignition switch apply 12 volts directly to the ballast resistor. Not wanting to disrupt my harness, I just connected a temporary exciter wire between the 12 volt side of the ballast resistor and the alternator.

When that temporary exciter wire includes a 194 side marker type bulb in series, the system all worked as normal.

When I took the 194 bulb and socket out of the wire and connected the 12 volt side of the ballast resistor directly to the alternator with a plain wire, the engine continues to run after I turn off the ignition key.

Clearly an exciter wire needs to have either a resistor, an indicator lamp, a diode, or possibly a relay to prevent run-on after you turn off the ignition.

Mark

Here is my free detailed analysis and summary. ©

There are folks who have a direct wire from alternator blade terminal 1 to ignition and have no run on.
There are folks who fix the run-on with a resistor or bulb solution.

There are so many variables with harnesses kits, ignition switches, HEI, Pertronix.....Owner wiring and miswiring. . Some internet info and diagrams show no bulb. Just run a wire to ignition. These folks are the ones who have done it with no bulb and are OK. So they advise that way. We don't know anything about these cases. I want to figure out why some do, some don't have run-on.

Lets talk ballast resistor system/10si alternator 3 wire/12V conversion.
If that system has run-on, here is what must be happening:
If you attach the alternator exciter wire and the coil wire to the same terminal on the ignition switch, the switch operation has no effect. Does not matter if that ignition terminal is dead after switch is OFF. The wires are touching each other outside the switch. Which gives a straight thru path (feedback) for voltage/current from a spinning alternator to coil to keep the motor running. (run-on)

Remedy:
Attach the exciter wire direct or thru an indicator bulb to the ACC terminal, then when switch if OFF there would be no connection to the coil and motor will stop. When switch is on, both terminals provide voltage. The "ON" and the "ACC" are connected together internally when switch is on. Be sure "ACC" and "ON" do not have continuity when switch is off.

On foot stomp/push button systems, the 3 terminal ON/Off switch may be useable.

I'm getting ready to install my new alternator. I was thinking of doing the tests you did, but now I don't have to. Thanks.

Still, the difference between the light, a resistor, a diode or direct connection is interesting. If you replace the bulb with a resistor or diode and the resistance is nearly the same as the bulb's resistance, I don't see an issue. However, if the resistance is higher than the bulb, the alternator may "think" the battery is low and overcharge the battery. A direct connection (no resistance) may charge the battery at a lower rate.

Since I didn't want an idiot light on the 41, here is what I did:



Wiring a 3W alternator with a DA Plug

In my opinion an indicator light (idiot light) is a very necessary feature to have. My suggestion in a previous post here will allow alternators to be installed with or without an indicator light, no diode or resistor and no run on. With most ignition switches.

From what I understand, once your bulb goes belly up, you have a problem.
That's why I opted for keeping my amp-meter so I see what's going on.

Frank

Hey Bartamos, I thought this remedy was done back when I was doing the tests. Were you hoping I would do another different test?

I also demonstrated that the system works as it should if the exciter wire connects to the IGN side of the switch as long as the wire includes the indicator bulb. I like having the indicator "idiot light" bulb in the system.

I suspect the diode solution may present a slight problem because of the half volt voltage drop across the diode. Probably not something to worry about.

Mark

I want to give much credit to "59Fleet" (Mark). He is the one who "sparked" my mind to explain run on. He did an experiment where he attached the exciter to ACC, which was isolated from "ign on" and all was well. Then on 1/23/22 he disproved his own result. I believe this second "more pure" test was in error. Disregarding that second test, He did prove that what I'm saying about wiring exciter to the ACC terminal on the ignition switch is the answer.

As far as bulb burning out, if everybody is such a gauge reader, surely they will notice, during the "bulb check" phase of key on, that the bulb did not come on.
Even if not noticed, the alternator will start charging at higher RPM due to residual magnetism. It is a very good idea to have a indicator light with your ammeter or volt meter.

Mark, the point I am making is that I believe their is no relation to the bulb and motor "run on". The "run on" is cause by not isolating the coil power from the alternator exciter power.

Your last test with ballast resistor and all that does not match the earlier test when you "shunt" bypassed the bulb and motor stopped as normal. This was done with a isolated ACC power supplied to alternator. In that same post you also confirmed that the alternator will charge without a exciter....with RPM increase.

You got me thinking and I have explained how to eliminate run on by isolating the exciter wire by using the ignition switch ACC terminal for the exciter wire. This is due to one of your experiments. Then you confused by saying you do need a bulb in subsequent posts.

If I read all that correctly. Please read your post and tell me if I'm correct.

Commentary:
I hope we can finally get this issue solved. Diodes, resistors, bulbs, run on..........exciter wire. It seems real easy.
The bulb was never meant to provide anti-run on resistance. It was used as an indicator. The myth has been perpetuated for 40 years.

ISOLATE THE WIRES FROM EACH OTHER!

I probably was not clear. The second (pure) test was done with the exciter wire connected to the ballast resistor which is connected to the IGN side of the switch. If when connected to the IGN the exciter wire includes a bulb the alternator works as it should and the motor does not run on. When it does not include the bulb the motor does run on after the switch is turned off. If you have a proper resistor or idiot light in the exciter wire it does not matter whether it is attached to the IGN or the ACC of the ignition switch.

Mark

I will repeat what I said in a simpler way. If the exciter wire is attached to the ACC terminal of the ignition switch and the ACC terminal is not connected internally to the Ign "ON" terminal of the ignition switch, the motor will turn off. No bulb required. No resistor required. There will be NO BACKFEED PATH from the alternator to the coil. The exciter wire will be dead ended. You proved this but don't know it.

What is "not clear" about your statements?

"Then I bypassed the bulb with a shunt which would be the same as a straight wire from the ACC side of the switch to the alternator. The alternator began to charge immediately when the engine fired up. When I turned off the ignition the engine died just like normal. I repeated this exercise several times and the engine never ran on after the ignition was turned off, no different than with the indicator lamp in the circuit."

"Bulb removed, inserted a metal blade in its place."

Oh By the way, if anyone is trying to contact me, I've moved recently..........

Traded up to a Ford, I see.

Had to pull it out with a Chevy truck. Got it started then.

The Sheriff pulled me over and just gave me a warning. "If you get back in that and drive it, you are going to jail"

Bartamos sounds like a real duce...

Good one.

Back on topic.

There is another possible issue with simply connecting the exciter wire to the ACC terminal. If you switch to ACC to listen to the radio or charge your phone, you will also be exciting the alternator. This may run down the battery faster than expected. I hope to finish the install today - I will see what happens.

You won't switch to ACC when the truck is running. The alternator won't be spinning. Won't be "drawing" any battery power. The phone charging would be on a unswitched source.

LeeD You know when the Delco engineers woke-up to the fact that it's hard to run amps thru brushes that is when they turned the system around and ran the CONTROL system thru brushes. That is when the alternator was born ! I would listen to drdoug !! When a 6-volt truck comes to me (about 30 so far) my first move is go to alt and 12 volt.

JW51 In about 1983 an old guy who started re-winding generators in 1936 came to me ,eventually we became alternator re-build partners,now he really knew a lot about a delcotron. He showed me how to build alternators that would prime at a low RPM like bolters need for their trucks. My local junkyard guy saved me several delcotrons that now wait for truck service or are repair parts,HEI,s too.

Interesting how a post asking about brackets gets so far off. Me included.

To summarize on topic. Brackets are available as posted. DIY brackets are fairly easy to design and build.

It is unarguable to stay with 6V/generator except for nostalgia.
Not cheaper, not more reliable, more hassle to find parts. More wiring. More voltage drop. Less output.

Thanks Bartamos, I'll lock this since it has wandered well off the original track.

If Y'all want to continue the conversation, take it to the 'spoon, or start a new topic.

Thanks