VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Battery discharge question

Hello All,
On Sunday I had my 51 in a local car show. All went well starting the car in the morning. At the show I decided to not disconnect the battery (green knob) for the day and when I went to start the car to go home the battery was dead. I got a jump and drove home with no problem. When I got home and shut off the engine, I noticed that the ammeter was pegged dead left indicting a strong discharge. I opened the disconnect switch and the ammeter went to center. Closed the switch and it went to the left. There were no lights on and everything was normal except for the discharge. I took off the cover to the voltage regulator and found that the 2 contacts to the far right (passenger side- the one with 2 points) were closed. When my friend pulled the points away the discharge stopped and the gage returned to normal. I checked the point opening as per the service manual and it was .020". Now the points remain open as they should and, after charging the battery, it started fine.
Any thoughts as to why this happened? Suggestions for making sure it doesn't happen again? Any help is greatly appreciated.
Jeff

My best guess is that those points need to be cleaned with a point file. Then the gap should be reset. Hopefully that will solve the problem. If the one point is too pitted they will stick again.

Contact deterioration is a common issue in direct current systems. In a direct current system the spark always jumps the same direction when the points open and close. With each spark there is a very small amount of material transferred from one contact to the other. Over many cycles that material transfer becomes a projection on one contact and a pit on the other. The transferred material has some oxidation in it so it does not conduct electricity as well as the remaining surface of the contact. The remaining smaller contact surface has to conduct the same amount of electricity as the new contacts did. There is more current going through a smaller area so the contacts get hotter. That leads to them sticking.

This is the same reason that ignition points need to be replaced. It is also the reason that typically the voltage to the points in a 12 volt system is reduced to 6 or 7 volts. The lower voltage produces a smaller spark so less material is transferred ao the points last longer.

We do not have this problem in our homes with light switches because they are operating on alternating current at a fairly high frequency (60 hz for us here in North America). The spark when the contact open and close will jump in either direction based on the direction of the current at the instance they open or close.

I have never had good results "saving" a regulator once the contacts start sticking. It seems like once the points stick they are so deteriorated that they will always get too hot and stick again.

Sorry for the long answer to a simple question.

Rusty 37 Master,
Thank you so much for the LONG answer. I really appreciate the time you took to explain. I think I have the issue fixed. I actually did what you said about cleaning the points except that the ignition file I have is thicker than the .020 that the points are set at so I used some fine sand paper. I also had the battery tested and it was failing badly so I replaced it. Started right up and the ammeter went to neutral in a few seconds. I shut the car off and turned the battery switch to off and the ammeter stayed right at neutral.
I learned something very interesting about the battery and will post in a new thread.
Thanks again. for the quick response.
Jeff

Hi Jeff,

The ammeter should read neutral with the battery disconnected. The key is to keep an eye on it when you turn the engine off and the battery is connected. If it does not read neutral there is either something still taking power such as lights or a clock or the points are stuck closed.

It is hard on the generator when the points stay closed and the battery discharges through the field and armature coils. All the energy in the battery is converted to heat in the generator. In your case the bad battery might have saved the generator. There was not a lot of stored energy in it.

One other point is there have been many problems reported on the AACA site with those green knob battery cut off switches/ terminals. I went with a Cole Hersee battery switch.

Dave

I would suspect that the cut-out in the voltage regulator is acting up. If it were my car I would replace the voltage regulator.

Well I thought I had it fixed after installing the new battery, cleaning the points, and adjusting the gap but last night we went to the local A&W and when I shut of the car the ammeter was pegged left again. I guess it's time for a new VR. Can original VR's be rebuilt?
Jeff

Sorry to hear that your efforts were not as successful as you wanted. In general that has been my experience with voltage regulators.

The other limitation today is finding a good new regulator, 6 or 12 volt. Based on what I read there is lots of junk out there.

Check out this business.

Precision Power

Rusty, you're missing the : after the https. It comes up can't find the page.

Thanks Tiny!

Let’s try this link.

Precision Power

Thanks for this link! They claim on their site that they can rebuild an original VR and can convert to solid state. Either of these options would be good if the price is right. I contacted them and will see if I get a response.
Jeff

Jeff,
Not sure if you ever got a response back. I called this morning and asked about a solid state for my '41. Was quoted $350 and four weeks. Have to send a donor regulator in.

Thanks for asking! I had a great conversation with them on the phone. They said they could absolutely rebuild my VR but before I get it to them he advised that I do a few things , which he detailed, to maybe fix it myself. Since I'm in the Detroit area and they are in Lansing (about an hour away) I could bring it to them and, if it's only minor adjustments /repair, I could wait and take it home with me. After Carlisle I will address this again. I'll let yo know when I do.
Jeff