Vetterodder

Years ago my `65 was overcharging. The problem turned out to be the ground wire to the regulator was broken inside the insulation. By time the problem was fixed the battery and alternator were toasted. The problem was found by running a jumper wire from the frame to the regulator. In my case, voltage dropped from almost 16 to just over 14.

plaidside

I have an article I wrote on theory and diagnosis of these charging systems.
Send me your email address and I will send a copy.
Joe

watson

Thanks everyone, I let the new battery charge on just the battery tender until it came up to a full charge. Now the charging voltage at 2500 RPM is 15.2 volts. That is a big improvement over what I saw with the old battery, but still a little high for me and I am still concerned about damaging the new battery. I may swap regulators with my 65 just to see if it changes.

dplotkin

15.2 volts is too high for most batteries. A conventional flooded cell battery will tolerate that but you will need to add water. That voltage is not great for light bulbs.

It is possible that you've got your hands on several bad regulators. I've noticed that the aftermarket mechanical Regulators sold in a Delco box consistently overcharge. I've also found electronic substitutes will work fine initially and then drift to overcharge. See if you can lay your hands on an NOS Delco regulator. Otherwise you'll have to keep installing Regulators until you find one that will hold your charging voltage to between 13.8 and 14.2 volts or thereabouts.

Dan

watson

OK, I believe that I have solved my problem. I went through the testing for the regulator and alternator, thanks to Joe Fisher, and discovered a possible issue with my alternator. To confirm everything, I took the alternator to a local shop that rebuilds them and had them test it. The guy said that it was OK. He also confirmed that almost all new regulators are junk and that they all over charge. My last one was better than the first, but it was showing 15.8 volts at 2,000 RPM. He suggested that I could switch to a new single wire alternator with the built in regulator. I decide to do that and I was able to leave the old regulator and wiring in the car so that things still look the same. I just disconnected the regulator plug and put it back a little lower than where it was so that the contacts do not connect. The back of the new alternator is slightly different, but very close. I fully expect to get grief from the local NCRS guys, but I am used to that. Now, the battery shows a charge of 14.7 volts at 2,000 RPM and life is good again. Thanks for all of the help.

jim lockwood

14.7 Volts is still too high. The goal is ~14.1 Volts.

scowser

I still think you should check it out with a regulator you know is working properly. Changing an unknown for another unknown gives an unknown diagnosis. See posts 19 and 20. At least I assume it is working properly but check the charging rate on your '65 first before you switch it.