Drove the '72 Cutlass to town Saturday night, parked it in the 'shop. Drank so much that I couldn't drive Sunday, so she was parked.

Now, Monday, she has about 5 v on the battery. Deduced that she was discharging somehow, and found that there was a connection between ground and the + terminal on my French aftermarked internally resistored genny. Took the generator apart and isolated it so that there's no longer any connection between the + terminal and ground. So far, so good. Then I measured if there was any connection between ground and the wire running to my genny idiot light.

Yup, about as good a connection to ground as you'd expect from a wire that size. Is this supposed to happen, or is that wire discharging my battery through my genny? I'm in the process of charging the battery now, so I can't start the car and see how well the genny charges yet.

 

Hi Seff, are you sure you wern't in a drunken stupor and left something on. If you unplug the lite wire from the gen with the key on the lite should go off. If it goes off the lite wire should be ok. Where did you find a connection between + and - in the gen? That would cause a drain.

 

I love to discharge my battery in the morning

 

Stellar: I parked it before drinking, I'm not THAT dumb. :P I measured the Junction Block against the ground lead, and there was a connection there, causing a drain. I then isolated the connection to the generator, where it turned out that it isn't the wire going from the alt to the junction block that's giving off power, but the generator itself.

Measuring the generator + terminal and the ground yielded the cause of the problem - the generator was draining power. I took the genny apart, isolated all the screws, and put it back together. Measuring ground against junction block showed no connection - excellent. But, now my genny isn't charging. I'll see if I can find a parts diagram of my type of generator, so I can tell you which screws I isolated.


805cut: Don't we all? Erm, I mean, no comment.

 

HAHA sorry i just had to..

 

Humor is the spice of life. :P

 

Your mistress told me you think it is a D cell, but really it is more like a AAA Sorry, i couldn't help it either.

 

Ahahaaha damm! Whatever i didnt like her that much anyways

 

I just looked at your august 12 post #6 and it all looks correct there.

 

Right, I already had a picture. Here we go:

btN27.jpg

Wire 1 is the plus lead on the back side of the gen. Wire 2 holds the ribbed diode housing thingy (ranging between 1 and 2) to the housing. Wire 3 is the lamp wire, running to the idiot light.

Due to the ribbed diode housing thingy being conductive and not isolated from the housing, and thus ground, it was draining (discharging, ho ho ho :P) the battery, since it was effectively connecting plus on that terminal to ground on the gen. I put tape under the ribbed diode housing thingy, as well as around wire 2, meaning that there's no connection between plus and ground on the generator itself. There's also no connection between plus and screw 3, the lamp screw.

Somehow it doesn't seem to be charging very well, though.

 

Stellar is the expert here, but I have to wonder whether you've got a short in your diode pack. It shouldn't be possible for it to leak to ground if properly installed, and low charging voltage can also suggest a bad diode.

- Eric

 

I agree with Eric. you probably have a shorted rectifier(diode pack). The rectifier has 2 plates. The positive one where the #1 battery post is and the second plate which is negative. The pos plate is insulated from ground with an insulator between the plate and the case. The negative plate and #2 bolt touch the case for a ground conection. Seff this plate and bolt should not be insulated from ground.

I would not say I am an exspurt as I am still spurting although at times a bit prematurely. Somewhat like a condenser or maybe a battery with little reserve capacity. Since my connection has been showing high resistance lately I think even disconnected my battery may soon start being self discharging.

 

As long as the discharge is useful, I'm happy.

Right, this means I'll ground plate 2 again, and see if we start charging again. Cross your fingers.

I'm just glad we identified a problem - leaves me less clueless.

 

Rectifier. Right.

I knew diode pack didn't sound right, but rectifier just wouldn't pop into my head.

Guess my battery must need a recharge...

- Eric

 

How to check the diode pack.

Anyone that has been in an older alternator might remember before the diode pack there were 6 individual diodes. A diode pack still has 6 diodes.

The way to check a diode with an ohm meter is to measure across the leads and then reverse the meter leads and measure again. You should see high resistance one direction and low resistance the other direction.

Remove the diode pack and under the 3 posts where the stator leads attach there are 2 tabs, one from each side. Lift the tabs to separate them. One bank goes to pos and the other goes to ground. When you determine which is pos and which is ground, measure the ohms to each of the 6 tabs and then reverse the leads. You should be able to isolate any bad diodes that way. You can't replace an individual diode like you could on the older style, but you can find out if you have a bad one.

Good luck and happy troubleshooting!

 

My diode pack checked out, and I assembled the alternator with both banks as the positive side, and the one serving as the positive bank being isolated from the case - in neither configuration did it seem to be making much power, having about 12.5 V at the battery and 13 V at the alt.

How exactly do I determine the positive bank?

EDIT: 12.74 and rising at the battery, 13.70 at the alt on the second start-up. I might just be okay. This is with everything off, mind you. Only HEI.

 

If the battery is very low, the voltage will start lower and rise slowly as the battery is charged.

If you could connect an ammeter in series with the big red wire, you would see whether it is putting out its full rated current.

- Eric

 

In the picture #1 is connected to the pos bank and #2 is connected to the negative bank. It looks like it is charging, but the battery may still be low. Recharge the battery full and retest. Can you have the battery tested?

 

On subsequent tests it's charging like it should, and voltage is as it should be. I'll test it tomorrow, to see if anything changes overnight.

Glad to know that I got the positive and negative banks right in the alt. The original problem was caused by the positive bank not being isolated from the case, making it drain the battery overnight, but still charging.

 

Damned French.

- Eric

 

I'd just as quickly blame the PO. You'd get nightmares looking at the wiring in this car.

 

I am suprised you didn't have big sparks and melted wires with the alt positive post grounded. Good that all is working now.

 

This is a French alternator, it's designed to go behind your back and screw you while you're sleeping it off. Sneaky snail-eaters!

Thanks for the help, guys.

 

Due to having too much time at the workshop, I decided to clean up my battery connectors, and generally tighten everything down - torqued my spark plugs to 15 when installing, and the CSM says 35, so I corrected that (entire driver's side bank were loose), checked fluids (burns too much oil, I think), and tightened the BAT wire on the alt. Afterwards, as I was reattaching my bat plus terminal, sparks. Well, ****.

You guessed it, the alt. Seems that tightening the screw caused my isolation tape to slip, making for an even better short circuit! So, I took the alternator apart, again, and isolated it with a piece of plastic. At that point it didn't charge, so I took it apart, once more, to see what was going on. Everything was assembled correctly (or rather, I noticed no mistakes), so I cleaned all conducting surfaces, and reattached it. 14.60 V! The car runs unaffected without the battery connected, so I'm a happy kid. Crossing my fingers for it being the last time I have to take that sucker apart.

 

I went to the workshop to help dad put up a wall, with a detour to the pizza place. Couldn't start once I'd fetched dinner. Twice now I've been able to measure the voltage over the alt as nothing after a start, but when I rev the engine a fair amount, it jumps to supplying 14.4-5 V.

Is it normal behavior for the alt not to start working until the engine's been revved? I'll measure the approx. amount of revs needed to "wake it up" tomorrow.

 

It sounds like the small wire is not activating the alt. The small post next to the battery post should be hot with the key in the run position and dead when the key is off. This wire is a resisted wire. If you start it and it does not charge, try putting a test lite between the 2 posts on the back of the alt. It should kick in right away when you do that.

 

That wire runs to the gen idiot light, yes? It has a connection to ground, and is not currently connected to the alt. I'll fix that, and see if it doesn't make the alt activate when I start the car.

Man, I'm learning new stuff all the time.

 

If that wire is grounded the lite will be on all the time when the key is on even if it is not connected to the alt. Is this what is happening?

 

No, right now the light isn't on because the blue wire isn't connected to the wire from the light. When those two ARE connected, the light comes on at the same times as the oil lamp, and only then.

 

hook it up and see if it charges at idle.

 

Hooked it up. The light doesn't come on when I turn the key to run.

EDIT: And no, I have to rev it to get it to charge. Hm. I'll see if it's hooked up to the lamp properly.

 

Disconnect that wire from the alt and ground it. With the key on in run position it should lite the idiot lite. If it does lite,the wiring and bulb are ok.

 

Light and wire are OK. Secured the connection to the alt, still nothing.

 

I'm gonna sleep on this I have to get up in 3 hours. With the engine running and the gen charging after being reved up, is there any voltage at the small post on the alt? Good nite. I'll get back later today.

 

The voltage at the small terminal (the lamp post, hah hah) is very close or the same as at the big post. 14.4-14.8 V

 

This looks like the alt is working the way it should. Do you have a volt meter? There should be 12 volts at the light wire with the key on and wire disconnected from lamp post. If you ground this wire with the key on the idiot lite should come on.

 

I have a multimeter, so I can measure ohms, volts, amps and whether there's connection between elements or not.

I'll try that. Can this have something to do with my alt not having a capacitor/transistor/the little round devil?

 

I swapped my Alt. to a single-wire, high amp flavor. It's gleams with a bonus chrome case. For $120 new, it would be what I consider cheap. Maybe your French bugger should be retired as a monument of frustration?

 

Quite possibly. I can work for six hours on this thing before it'd be cheaper to buy a new one, and that's only if I get money for my free time. Plus, it frustrates me more that I can't find the fault than it does to spend time on it. :P

 

Alright, I took the alt apart again. I'd switched the lamp post and the negative bank fastening post around, meaning that the screw in the lamp position wasn't connected to the regulator. Easy fix. My idiot light now comes on, and my alt charges at 14-15 V, and wakes up immediately.

Now all that's left is the radio noise from the alt. :P