I have several tractors with Delco 1 and 3 wire alts on them. Question on the 3 wires- I finally found a nice red "idiot" light that will fit where I want one to go. This is the light that I understand runs from the #1 terminal, (closest to BATT stud on alt), to a switched stud on the ignition switch. My question is simple and rather dumb I suppose- 2 spades on the light, do they both get wired in the line (series?) or does one go in the line and one to a ground? For kicks I held one spade on the batt term of the alt while it was running and touched the #1 line to the other spade and it lit up, but didn't start charging, but did start charging when I held the wire to the stud directly. Maybe someone has addressed this but I missed it. It's all pretty much magic to me...
- Thread starter Bret4207
- Start date
old
Well-known Member
- Location
- Camdenton Missouri
The light is wired in line of the #1 wire NO ground.
<img src = "https://www.gondtc.com/~blweltin/Bob/AlternatorHarness.jpg">
Pretend the diode in the photo is your "idiot light". (They can be used interchangeably.)
The coiled red wire would go to the "switched side of the ignition switch.
I hope your little light isn't an LED, typically they don't pass enough current to "excite" the alternator.
Also, an incandescent "idiot light" with a tiny bulb may not pass enough current.
As an example, "194" lamps draw about .27 Amps, and work well for this use.
Pretend the diode in the photo is your "idiot light". (They can be used interchangeably.)
The coiled red wire would go to the "switched side of the ignition switch.
I hope your little light isn't an LED, typically they don't pass enough current to "excite" the alternator.
Also, an incandescent "idiot light" with a tiny bulb may not pass enough current.
As an example, "194" lamps draw about .27 Amps, and work well for this use.
john in la
Well-known Member
You need to have a light fixture that is isolated from ground.
If 1 of the spades hooks to ground (like a normal light fixture would be) it will not work.
One side of the bulb gets hooked to keyed power.
The other side gets hooked to the #1.
This excites the alternator and makes it start charging.
Before it starts charging or if it quits charging the light will be on as power flows threw the light.
With the alternator charging there is a equal amount of power coming from both wires so the light goes off.
If 1 of the spades hooks to ground (like a normal light fixture would be) it will not work.
One side of the bulb gets hooked to keyed power.
The other side gets hooked to the #1.
This excites the alternator and makes it start charging.
Before it starts charging or if it quits charging the light will be on as power flows threw the light.
With the alternator charging there is a equal amount of power coming from both wires so the light goes off.
Janicholson
Well-known Member
It is easy to make that dash light work to excite the alternator. Use a 10 to 20 ohm resistor in parallel with it. (across the
two spade terminals. this will decrease the resistance, but allow the light to remain functional. Jim
two spade terminals. this will decrease the resistance, but allow the light to remain functional. Jim
If your little light wont excite the alt. get a side marker light socket for the 194 bulb and wire it in. One wire on each side of 194 socket it will excite it then. Each lite wont know the other is even in circuit. I have 2 tractors wired this way and they work fine. However you will have 2 bulbs to keep burning. You can hide the 194 socket behind dash behind your little light.
Janicholson
Well-known Member
The dash light cannot draw 6 amps. It would be a melted cinder if it did. The alternator probably requires 150 to 250 milliamps.
(hundredths of an amp) to excite. The indicator lamp might draw 50 ma. not enough. Jim
(hundredths of an amp) to excite. The indicator lamp might draw 50 ma. not enough. Jim
I was thinking that was a lot. Maybe it's Chiwanese for this lamp will handle up to 6 amps? I dunno, the box clearly states "6 amps". It's busted anyway, I'll look for another alternative.
On another note, where does one find .5 amp 600v fuses for your mulitimeter? Last time I got some was at Radio Shack probably 15 years ago!
old
Well-known Member
- Location
- Camdenton Missouri
Good chance an auto parts tore will have the fuse you need. Or if that store that was once a Radio shack is still open just not radio shack it may have them. I know what radio sack went out the store that was there stayed open and pretty mush sells what they did before radio shack went under
old
Well-known Member
- Location
- Camdenton Missouri
As for another way to excite the alternator and yet be able to shut it down again one can use a ballast resister like the O'Reilly's part number VR-1 or VR-2. Or a diode or like my W Speed patrol is set up the light switch. You turn on the lights and it also excites the alternator at the same time. Then shut the lights off and they stay lite as long as the alternator is working. My Oliver S88 has the ballast resister set up. It was that way when I got it so I left it like it was since it works
I have one tractor that I just used a switch in the line. Start tractor, flip switch, ammeter stars showing a charge, shut switch off. Kind of a pain to remember and the switch has been known to get left on. A resistor is a good idea, a lamp just seems "traditional".
Hey, if nothing else, this finally got me to look up what all those little symbols on my digital MM mean. The old faithful analog I more or less get, but the new job has all sortsa little squiggly lines that I had no clue what they meant. The internet and You Tube are great for stuff like that. Lots clearer than the chiwanese booklet that came with the DMM that had little info I could decipher. Electricity is still magic, but it might be I can understand a little of it!
Janicholson
Well-known Member
Leaving out the decimal point .6 amps might be right. A normal round 12v headlight draws about 6 amps or about 72 watts. There
is no electrical way for a lamp, like your indicator, to allow 6 amps to get through it. It has no way to allow more current than
when it is connected directly to 12v. Jim
is no electrical way for a lamp, like your indicator, to allow 6 amps to get through it. It has no way to allow more current than
when it is connected directly to 12v. Jim
old
Well-known Member
- Location
- Camdenton Missouri
Thing is a light bulb can burn out and you not notice that is did not come on so then you are out suing the tractor you shut it off and then walk home due to the battery being discharged and it will not start. A resister is not likely to burn out.
As for the switch thing I used a 2 position switch one notch out tractor starts. 2 notches out head lights come on and alternator gets excited. That way one cannot forget to shut the switch off or you do not shut the tractor off
As for the switch thing I used a 2 position switch one notch out tractor starts. 2 notches out head lights come on and alternator gets excited. That way one cannot forget to shut the switch off or you do not shut the tractor off
old
Well-known Member
- Location
- Camdenton Missouri
That works if one has such a thing laying around but very few people do and fewer even know what one is. My self I have diodes laying around but I also have a lot of odd stuff on hand
teddy52food
Well-known Member
I have my H wired through an oil pressure switch. When the pressure closes the switch, the alt. starts charging.
Rich'sToys
Well-known Member
- Location
- Southern MN
I have three with alternators. I used a diode as shown in Bob's illustration. I had gotten a small package of diodes at Radio Shack. I've also seen them on Ebay.
The only thing I did different was instead of running that wire all the way back to the ignition switch I just ran it to the + side of the coil.
BarnyardEngineering
Well-known Member
- Location
- Rochester, NY
I've been using an LED "idiot light" on my H for years. Alternator excites fine.
I figured it's a light and a diode. Two birds with one stone.
I figured it's a light and a diode. Two birds with one stone.
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