3 wire alternator nightmare

[frickenbored]

Hi everyone,

I haven't posted in a long while but the last time I was here I got so much great information from a lot of people. I've got another problem so I figured I'd ask for help here again. I have a Case 350 track loader with a case 188 4cyl diesel. It used to have a generator but it was replaced about 30 years ago with a delco si 3 wire alternator that was never hooked up correctly so it never charged, which wasn't a huge problem because it has 2 batteries and zero electronics, the headlights were broken a long time ago.

Well last weekend the vbelt broke so I figured while I was at it, I'd replace the alternator, wire it up to work, and wire some new led headlights. So I ordered a new GM SI internally regulated 63amp 3 wire alternator, some wire, a new ammeter, and an indicator light. I watched a ton of YouTube videos and studied a bunch of 3 wire alternator wiring diagrams.

I mounted the new alternator, ran a wire from a 12v key on circuit, to the idiot light, to pin 1 on the alternator for the excite circuit. Then I ran pin 2 directly to the battery output on the alternator. And finally I ran a thick wire from the batt output to the positive post on the starter solenoid. Following the attached diagram exactly. (I haven't hooked up the ammeter yet, I just wanted to make sure the alternator would charge)

I start the tractor and check across the battery terminals with my meter...nothing. 12.03v. The idiot light is on but dim. I hold a wrench up to the back of the alternator and I can feel a strong magnetic field. When I unhook the thick charging wire from the battery and check it with my meter I get 14v but as soon as I connect it back to the battery positive I get zero charging. I've tried running the charging cable to the starter and to the battery. I added a grounding cable from the alternator to the engine block and still nothing. No matter what I do I get 14v with the charge wire unhooked and 12v with no charging with the charge wire connected. Has anyone ever seen anything like this? I'm not sure where to go from here.

 

[willie59]

I'm no expert on alternators, but I think I'd toss that three wire system and simply put a Delco 1 wire on it. And I'm not fond of Amp meters at the instrument panel, that requires a heavy gauge wire from the Alt, to the gauge, then back to battery. A volt meter gives just as good information and only requires like a 16 gauge wire.

 

[Truck Shop]

What rpm, just checked at idle, some three wires need the rpm to hit 1000 plus before
it starts charging, have a forklift in the shop with a three wire that has to see some R's.

 

[willie59]

What rpm, just checked at idle, some three wires need the rpm to hit 1000 plus before
it starts charging, have a forklift in the shop with a three wire that has to see some R's.

I've seen that happen before. Had a customer that fitted an automotive (gas engine) alternator on a Deere 4239 diesel, wouldn't charge at idle. Fitted a slightly larger diameter pulley on the alternator and fixed the problem. Diesel engines run at a lower rpm than gas engines, generally speaking.

 

[ozarkag]

Not sure why the jumper to terminal 2. Should work without that. But definitely agree, go with the 1 wire. It will either work or not. . .

 

[frickenbored]

I actually tried a Delco 1 wire alternator first. I bought a 120amp, delco 10si, self exciting, low rpm turn on alternator. I ran an 8 gauge cable from the output terminal on the alt to the positive cable on the starter solenoid. Nothing. It wouldn't charge no matter how high I revved the engine. The paper that came with the alt said it turned on at 1400rpm. According to Google the case 188 engine has an rpm range from 600 to 2100 (the tach used to run off the generator so this tractor no longer has a tach). I figured the engine just didn't spin fast enough to start the one wire alternator so I bought a 3 wire alternator since the key on circuit is supposed to turn on the alternator regardless of rpm.

 

[willie59]

I actually tried a Delco 1 wire alternator first. I bought a 120amp, delco 10si, self exciting, low rpm turn on alternator. I ran an 8 gauge cable from the output terminal on the alt to the positive cable on the starter solenoid. Nothing. It wouldn't charge no matter how high I revved the engine. The paper that came with the alt said it turned on at 1400rpm. According to Google the case 188 engine has an rpm range from 600 to 2100 (the tach used to run off the generator so this tractor no longer has a tach). I figured the engine just didn't spin fast enough to start the one wire alternator so I bought a 3 wire alternator since the key on circuit is supposed to turn on the alternator regardless of rpm.

Have you got a ground wire going from the frame to the engine? If that engine doesn't have a good ground then nothing electrical will work as the engine is isolated on rubber mounts.

 

[willie59]

On second thought, then the starter wouldn't work. I'm baffled.

 

[Delmer]

The engine pulley is quite a bit bigger than the alternator pulley, so it should have turned on the one wire when you revved it. Did you start with charged batteries? might be as simple as nearly dead batteries and not much amperage at idle. Is the idiot light an LED? might not flow enough amps to excite the alternator, but seems like it is, check the voltage at #1 terminal when hooked up and running. You could try anything conductive in the test hole to short the tab to the case, looks like the oblong hole just to the right of the shaft in that pic, that bypasses the voltage regulator and goes to full output. I'd run it an hour and then check the voltage again, might just need to charge the batteries to get the voltage up.

 

[MarcusZ1967]

Two batteries?
I'm not gonna assume so I'll ask.



12v or 24v?

 

[56wrench]

Willie59, didn’t you mean to say ‘smaller’ pulley on the alternator so it would turn a bit faster?

 

[frickenbored]

The engine pulley is quite a bit bigger than the alternator pulley, so it should have turned on the one wire when you revved it. Did you start with charged batteries? might be as simple as nearly dead batteries and not much amperage at idle. Is the idiot light an LED? might not flow enough amps to excite the alternator, but seems like it is, check the voltage at #1 terminal when hooked up and running. You could try anything conductive in the test hole to short the tab to the case, looks like the oblong hole just to the right of the shaft in that pic, that bypasses the voltage regulator and goes to full output. I'd run it an hour and then check the voltage again, might just need to charge the batteries to get the voltage up.

The idiot light is led, although I've bypassed it and ran a test wire directly from the battery to pin 1 with no change.

My batteries are not in the greatest shape and they're actually pretty dead at the moment, I've been using a jump box to start the tractor. I'll throw the charger on in the morning and see if full batteries make a difference.

Two batteries?
I'm not gonna assume so I'll ask.



12v or 24v?

Two 12v batteries hooked up in parallel for a total of 12v still.

 

[MarcusZ1967]

The idiot light is led, although I've bypassed it and ran a test wire directly from the battery to pin 1 with no change.

My batteries are not in the greatest shape and they're actually pretty dead at the moment, I've been using a jump box to start the tractor. I'll throw the charger on in the morning and see if full batteries make a difference.


Two 12v batteries hooked up in parallel for a total of 12v still.

Good on the 12v. Might ought to charge with a "good" charger, not one of the idiot box new ones....

 

[frickenbored]

Good on the 12v. Might ought to charge with a "good" charger, not one of the idiot box new on

I threw away all of those "smart chargers", worst things ever invented. Schumacher seems to be the only company that still makes reasonably priced manual battery chargers, I bought a couple of them.

 

[Coaldust]

10 ohm, 10w resistor or something like a #194 bub on the #1 indicator terminal, I recall. But, if you full field it with a paper clip and nothing happens, maybe the new alternator has a problem?

 

[Delmer]

Generally voltage is a better measure than amps, but you may have found the exception. If your batteries are completely dead, as in a dead cell in each, then they could show that low of voltage even though they're charging. Easiest to have a battery sitting at 12.7 then you know what's going on.

Another possibility is bad diodes, that could cause the alternator to show magnetism, but not put out amps and volts to specs.

 

[frickenbored]

Well I charged the batteries for a little over an hour, voltage showed 12.8V and the tractor started right up but still no charging. I took some pictures to show what I'm working with.

I just have everything hooked up temporarily, I wanna make sure I can get everything to work before I start installing stuff for good. My red indicator light is always on with the engine running. I have batt voltage going into the light but only 9.1v-10v going to pin 1. But even when I bypass the light and apply 12v to pin 1 it still doesn't charge. I have the wrench stuck on the back of the alternator to show that it is creating a magnetic field.

I dont know....maybe I'll take the brand new alternator out and have Autozone test it. It really seems like this setup should work.

 

[mekanik]

I put a 10si on a 310 John Deere last summer using the diagram below and it worked. I had to rev the engine up a fair bit to get it started. Where is the second wire from the charge light going at the left of the bottom picture? Also I think a LED may not have enough load for it to charge.

 

[Truck Shop]

One issue--the electrical parts end is terrible--the amount of poor quality is off the charts.

 

[Coaldust]

But, it says right on the unit, “ triple tested”.