Packard Forum Index » Post-War (1946-54)

It's called belt and suspenders:

ground strap engine to frame, ground strap engine to body. ground strap battery to engine. That covers it all.

If not a grounding problem then u have a regulator problem. How did it work with the OLD regulator????? Maybe put the OLD regulator back on to see if the problem stops.

Hello, all,

Thanks for all the great suggestions. I read them with interest.

I've given this thread some thought and now realize the system either charges the battery or it doesn't. I noticed it NOT charging when the headlights were on because that was when I had the biggest draw. With no electrical accessories running, but with the engine operating, the ammeter needle leans very slightly to the left (discharge) side.

A short time ago Jerry, my mechanic, got under the hood. I'd started the car and turned on the headlights. The ammeter needle was swung hard to the left.

Jerry started probing and testing. He had me rev the engine while he tested the generator and other electrical components.

Then he used a jumper wire. He jumped from the 'hot' (positive) wire on the generator directly to the positive terminal on the battery.

The problem instantly corrected itself. After he pulled away the jumper wire the correction remained. In other words, the simple jump seemed to fix the problem, at least for the moment.

He and I have no idea why this was. It seems either the charging system works perfectly or it doesn't work at all. Does anyone have any thoughts about why this is?

Thanks much,

Mark

I would think the needle should be to the right if generator is working and engine at more than idle speed. Curious how the battery is being kept charged if showing a discharge--unless the ammeter is not reading quite right.

On the other, it sounds as if your cut out relay in the regulator is dropping out for some reason when you turn on the lights. A surge when turning on perhaps? Jumpering connects voltage to the generator which energizes field coils and pulls in the cut out relay again. Is the regulator the correct one for the generator and car and properly adjusted for recommended cut out voltage? You might try the polarizing procedure. Doing it now won't hurt anything and might help. Essentially that's what was done with the jumper to battery -- except that with the generator running, couldn't get the full benefit. I would be tempted to add that ground strap or verify one is present since Tim says there may be one under the car next to transmission.

A quote from YOUR very first post of this thread:
"Some background: I've recently replaced the generator (rebuilt) and voltage regulator (brand new aftermarket supplier). "

REmove the NEW regulator and put the OLD regulator back on for a test. If problem stops then u know it has something to do with the NEW regulator.

I'm no expert, but it seems like we're chasing our tails on this one - really shouldn't be this hard.

Cap'n, has your mechanic hooked up an ammeter (like a Sun VAT unit) at the generator and compared its reading to the dash unit during the observed deep discharge event? That would show whether or not this is an instrumentation problem.

Also, test your ground connections for the generator and regulator to make sure that any shiny new paint isn't causing a problem. If ground isn't found where "expected", electricity will try to find it some other way - and funny things can happen. IIRC, you have the full diagram on the AEA chart.

Speaking of ground, you wrote:

Quote:
Are you trying to say that your mechanic jumpered the generator's ground (G) terminal directly to the battery's ground (+) terminal and solved the problem. That would indicate a deficient ground for the generator.

I'd do two very simple tests, and I'm assuming the ammeter is functioning properly.

First, I'd do the old standard test of momentarily grounding the field wire at the regulator. If things return to normal, it would confirm a functional generator.

Second, I'd remove the regulator cover, identify the cutout relay within the regulator, and put on the headlights, run the engine at a fast idle, and see if the cutout relay has closed. If not, I'd push it closed with my finger and see if the situation corrects itself. If so, you've got a bad cutout function on the regulator.

Hi,

The problem started when I had the old regulator in the car. It only seemed to grow worse when I installed the new one. Quote:

Quote:
Are you trying to say that your mechanic jumpered the generator's ground (G) terminal directly to the battery's ground (+) terminal and solved the problem. That would indicate a deficient ground for the generator.[/quote]


Sorry, gentlemen, I misspoke (miswrote?).

What Jerry did was to jump from the hot wire on the generator to the negative (-) terminal on the battery. This 6-volt, positive ground business tends to get me confused.

Anyway...on my car the terminal marked (-) is the terminal closest to the headlights. The terminal marked (+) is toward the firewall. Jerry's jumper went to the (-) terminal. He indicated the wire on the generator that he jumped from was the wire that carried away the juice the generator produces.

I hope this makes sense to those of you who understand these things.

Sure it makes sense, what he did was to bypass the regulator cutout. See my post above where I suggested you subject the cutout to a simple test.

There are 3 units within your regulator, one controls voltage, one amperage, and one connects (when the engine is running) and disconnects (when you turn off the engine) the generator from the battery; this one is the cutout. I suspect it is not functioning. Do you need help to identify which unit within the regulator is the cutout? It's the one with the largest, heaviest windings on the core, and adjacent to the BAT terminal. Why do you need the cutout? Because without it the battery would dicharge back thru the generator if they stayed connected when the car wasn't running. And in short order it would probably "cook" the generator.

Are you sure both the old and "new" regulator are the correct ones for your system? What year and model is this Packard? Delco or AutoLite system?

No reason to get confused by + ground. System ground is the polarity of the battery terminal connected to the engine block.

I don't completely understand these old charging systems, but have found that if I generally just follow the shop manual tests, the problem reveals itself in comparatively short order.

IIRC, we're working on a 1950 Standard Eight, but the 46-50 shop manual is rather scant on electrical service. However, I believe the Cap'n has both the 1950 AEA Tune-Up System Chart with complete vehicle wiring digram (on reverse) and the Serviceman's Training Booklet on Scientific Diagnosis, which covers the "Charging Circuit" (starting p. 12). Though that training book was published in 1951 (featuring the new 24th Series), surely the basics still apply - as the steps are written without regard to AutoLite vs. Delco. (Just be sure to follow the two-column format of each full page - lest ye skip a step.)

If the voltage regulator cutout relay was not functioning at all, I'd expect a discharge reading on the ammeter at all times that the engine was running, rather than intermittently - that is, only under conditions of high demand. In that case, the vehicle would be running off of the battery at all times (in sufficient for on any long trips), and would need to be recharged using an external charger.

While the generator and voltage regulator have both been replaced in this car, the problem continues and seems to be getting worse. Now, it's possible to have a new or rebuilt unit that's defective right out of the box, but there are other factors to consider.

Have the circuits between ALL components in the charging system and their connections been checked for excessive resistance? I'm still suspicious of a ground problem.