1959VetteJan

Folks,

I recently bought a '59 vette which the seller claimed to be free of any issues (sigh). Anyway, it appears that the battery is not charging. Here are the symptoms:

1. The voltage gauge never shows the needle traveling into positive territory. At best, even when driving and all lights & accessories turned off, it stays slightly below zero. When I turn on the lights or step on the break pedal, the needle moves further into the negative (draw) zone.

2. The battery charges fine and appears to hold the charge when charged with an external battery charger.


3. While I have not looked inside the generator, both the voltage regulator and the generator appear to be fine visually (i know, i know).

Is there some easy way for me to determine, if the generator is ok?

Thanks for your help.

Jan

1snake

Drive to your nearest AutoZone/Flaps/Kragen etc. They can do a complete test of the battery, gen. & VR without removing anything.

Jim

1959VetteJan

Thanks Jim - weather permitting, that's what I will do. We had snow yesterday here in Michigan. I have a hand-held volt/amp meter at home. Would this work as well in the meantime? Where would I measure the output at the generator and regulator?

Thanks,

Jan

JohnZ

Put the leads on your meter (set at DC volts) on the battery terminals with the engine off - a fully-charged battery will show 12.4-12.6 volts. Start the engine and run it at about 1500 rpm and do the same test - you should show 13.8-14.4 volts across the battery terminals if the generator is charging.

Donald #31176

Set the meter to DC volts and connect the pos. lead to pos battery post. Connect the neg lead to the neg battery post. With the engine @ a fast idle (1500-2000 rpm) the meter should read 13.8-14.5 volts if the charging system is up to par.

Frankie the Fink

All the above checks are great advice. Fortunately there are still folks that will rebuild the old generators. You can check out the local starter/alternator rebuilders and there is usually some old f@rt around that still knows how to do it. I found three in the Orlando area.

I now keep a spare voltage regulator, generator, starter and fuel pump on the shelf so I'm not off the road for extended periods due to "high failure" rate items.

1959VetteJan

Ok, I went ahead and tested this out. The battery has a full charge and shows 12.4. When the engine is running at 2000rpm nothing...same thing, so it is not receiving a charge. I tested it right at the generator and it shows 12.2 or so at 2000rpm and makes it up to 12.6 at 3000. It appears that the generator is generating something. Are these values enough for the gen, or should it be more? The wiring is all new and does not appear to be the culprit. That would leave the regulator (which by its appearance seems to be brand new as well).

Thank you for any further guidance you are ale to provide.

Cheers,

Jan

Pilot Dan

The faster the Generator spins, the more juice it should produce. A good generator should be producing 14 Volts above 2000 RPM. Try running the engine at 2000 RPM's with the wiring disconnected and you will get the true output. My bet is a bad generator.
Pilot Dan

Frankie the Fink

There are some tests you can do to isolate the problem between generator and/or voltage regulator. Its best to follow the shop manual but you can 'pinch hit' with this technique if you feel confident: http://www.nls.net/mp/volks/htm/gen.htm. Some of these tests allow the generator to "float" unregulated and it can pump out 35V which can ruin components....so if you aren't comfortable with more troubleshooting get some help.

1snake

Since you have a volt meter, the test is easy. We have already determined that something is wrong since the battery voltage is not to spec. with the engine running.
Here's what you need to do - disconnect all the wires from the generator, hook a volt meter to the arm. terminal and start the car. You should have between 2-6 volts. Now ground the field terminal and you should get over 15 volts when you rev. the engine. If you do, you have a bad regulator. If you don't, you have a bad generator. Simple as that. One other thing to check is to make sure the V/R and the gen. are grounded or it will show as a bad V/R.

Jim

1959VetteJan

Thanks for the great advice and hints. Will check it out and revert back.

Thanks,

Jan

Steve59

Just as a wild *** suggestion, make sure your gauge is wired correctly and not reversed. The wiring diagram in the ST 12 is incorrect.