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Wiring up a ford 1G alternator (ext reg)

10K views 14 replies 3 participants last post by  EOD Guy 
#1 ·
Hello - I built a portable battery charger/jump starter using a Honda GX160 engine and a 1G alternator & regulator from a mid 70's ford pinto. I have the unit functioning just fine, but it isn't right because the LED light i used (has a 600 something OHM resistor built into it) for the charge indicator doesn't shut off. The alternator is charging tho, because the battery only measures around 12.7 volts, and when the engine is started after I flip on the toggle switch i have installed, the indicator light comes on and the voltage comes up to 14.60 volts. The light does not go off, however, as it should after the alternator begins charging. Also, if I turn the toggle switch off, the alternator stops charging. I thought it would keep charging until the engine was stopped.. (as in, i thought it only needed switched 12v momentarily to "excite" the alternator). Heres how I have it wired:

Alternator "bat" terminal has 3 connections to it; a cable to the battery positive terminal, a wire to one side of my toggle switch, and a wire to the "A" terminal on the regulator.

The alternator "FLD" terminal is connected to the "F" terminal on the regulator.

The alternator "STA" terminal is not connected.

The alternator "GND" terminal is connected to the battery negative terminal with a jumper wire to one of the mounting bolt on the regulator.

The "I" terminal on the regulator is connected to the negative wire on the indicator light, and the positive wire on the indicator light is connected to the other side of the toggle switch.

The "S" terminal on the regulator is wired to the same terminal on the toggle switch that the indicator light is connected to (so they both get 12V when the switch is on).

I wired it this way thinking it was correct, but it must not be. Does anyone see where I messed up at??

Will post a pic of the wiring in a few minutes...
 
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#3 ·
LEDs won't work as a charge indicator light. They are polarized, I'm surprised you got it to light at all. You have to use an incandescent light.

When hooked up properly, one side of the bulb gets pos 12v from the ign side (key), the other side gets hooked to the #1 terminal on the alt (GM Alt).

With the key "on" and the alt is not spinning the #1 terminal is grounded internally in the alt and the idiot light illuminates.

With the key "on" and the alt is spinning, the internal ground is removed and pos 12v is applied. So now the light has 12v on both sides and can not illuminate because it lost it's ground.
 
#4 ·
Hook the s terminal to the sta terminal on the alt, the f to fld is fine like you have it. The bat post, the a reg terminal and one side of your switch go to the battery +. The I terminal on the reg should hook to the other side of your switch for ignition hot power so to speak. It doesn't need a light but if you want to use one you'll need a regular bulb not an LED and you'll want to run a resistor in parallel with it so if the bulb burns out it will still charge.

Sent from my XT1254 using Tapatalk
 
#5 ·
ah ha! thanks guys! The LED must be the problem. The LED has a resistor built in (not sure why, tho) and I knew that indicator circuit needed one, so I bought it and used it.

Initially I had the S terminal on the regulator wired to the STA terminal on the alternator, but the alternator didn't charge when it was wired that way. I will switch it back and try an incandescent light for the indicator...it isn't really necessary but due to my intended use i would like to have the light so that I know that its working. I have an ammeter I may use also.

Any idea what size resistor I need? Radioshack has tons of types, 1/2 watt, 1 watt, etc. in various ohms...I have no idea which one I need...
 
#7 ·
Ford had two wiring setups for the 1g alternator, the way I described was for cars or trucks with a warning light, the other way was for vehicles with a factory ammeter. You inadvertently wired it that way when you attached the s terminal to the switch and left the sta empty. That's why it started charging for you.

Whether you run an ammeter or not you can hook it up like I described in my first post and just stick your full current ammeter in the bat post to battery wire in the future. The factory ammeter vehicle were wired differently because Ford used a shunt style ammeter.

Sent from my XT1254 using Tapatalk
 
#8 ·
Ok. So far I haven't found a suitable light to use as an indicator, so for the time being I will wire it up without it. I can go ahead and use the ammeter tho, I have a couple of them sitting around in the package still.

What do I need to do to make it work without the light? I think the "I" terminal is unnecessary when there is no light installed so I should be able to remove that. I am guessing here.. that all I will need to do is just remove the LED (which has the red wire connected to the cold side of the toggle switch and the black wire connected to the "I" terminal on the regulator).

Do I need to move the wire from the "A" regulator terminal back to the "STA" terminal on the alternator, or is it correct where it is now (on the cold side of the toggle switch, only hot when the switch is on)?

Is the toggle switch even necessary? I built this as a portable unit, which has a 2,000 watt Winpower generator on it also. There is no battery (engine is not electric start right now), I have just taken 6ga cables and put clamps on one end and terminals on the other - the red clamp goes to the BAT terminal on the alternator and the black clamp to the GND terminal on the alternator. This means that the engine may be running sometimes with no battery connected to the alternator, and I think that would be ok, since it wouldnt have any way to excite itself - which is the same as having the toggle switch but leaving it in the OFF position...

Thanks so much for helping me out. I really appreciate it.
 
#9 ·
Don't put in a resistor, you don't need one. If you want to run a parallel switched 12 volt that'll work but why?

If you are going to put in a volt meter, you don't need an idiot light.

Just hook up a switched 12 volt to the exciter terminal and be done with it. I wouldn't use an ampere meter, I'd use a simple volt meter hooked up to your battery post clamp. Hook up the battery, volt meter reads "X", start the engine, volt meter should read 13 ish volts..... it's working
 
#10 ·
Hook it up just like my first post, f to fld, s to sta, a to battery and bat to battery +, I to switch to battery. If you don't use a light just hook I directly to the switch. Put the ammeter on the wire between battery and bat post.

I would use a switch because if it's hooked to a battery with the engine off the field current will drain the battery slowly.

Sent from my XT1254 using Tapatalk
 
#12 ·
Yes, after I wrote that last post I went back and ready the entire thread again and realized that you had already told me how it should be wired up. Sorry about that, I didnt reread everything again before posting.

As far as gauges go, I think EOD's idea about using a volt meter instead of ammeter is the way to go now that I think about it. I wanted the light so I knew the alternator was working, but that is ALL it will tell me. The volt meter will tell me the same thing, and if it is not charging, and the voltage level of the connected battery when the engine is off..

Does the volt meter just have a hot wire to the BAT terminal and a ground wire to the GND terminal? I dont think youd want the alternator to charge through the volt meter like it would do with an ammeter... These questions I could probably just look up, but id rather ask just to be sure...

I promise i'm not an idiot lol, this alternator and regulator came off my 74 pinto a few years ago after I swapped in a 91 mustang EFI engine, including its internally regulated alternator and I had only a little help from some wiring diagrams. (the alternator wiring was easy, I had the wiring from the mustang, all that I had to do was splice the indicator light wiring together) On this project tho, the wiring is all from scratch, I threw away the wiring from the pinto back when I did the engine swap in 2013.
 
#14 ·
Got it wired up and working. Good thing I kept the toggle switch, if you try to start the engine (recoil start only right now) with the switch on, its hard to start because of the load the alternator puts on it. You have to start it with the switch off and then turn it on. And it stays on this time, even with the switch turned back off. Once the engine is running and the alternator is switched on, it doesnt seem to be making the engine work hard... but it sure does make it tough to start if you switch it on before starting the engine.

Seems like everything is working correctly. I am highly impressed with this project. It looks pretty good and its very functional. A 2000 watt generator and a 65 amp battery charger (alternator) in one portable machine. Going to moiunt it on an old power washer cart next and put a regular automotive battery on it so it will work also as a portable jump starter as well.

Then add electric start to the engine....
 
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