Charging System, Comments on my diagnosis please Options

[HarveyH]

Well, I've been having some charging problems. Cleaned all the battery connections. Checked the Voltage regulation and found it was regulating a bit low, 12.4 Volts. Also did a field test per various writeups on the site, voltage tracks RPM up to 16+ Volts at 3200 RPM.

Got a new electronic voltage regulator: it didn't regulate at all, voltage tracked RPM as with the field test above.

Got another new electronic regulator . Checked regulation and it's not stable up to about 3100 RPM when it levels out at about 14.5 Volts. During runup it goes as high as about 15.4V. I'm still getting an alternator light

Brand new battery installed. Continues as above.

Cleaned the contact points of the old mechanical regulator and adjusted the vibrator points tension to get it to regulate at 14.5V. Much more stable than the electronic regulation at lower RPM's. Still get the alternator light.

Bad diodes in the alternator????? (IMG:style_emoticons/default/headbang.gif) Thinking the poor stability of the regulation with the electronic VR is that it's more influenced by AC than the mechanical regulator.

Thanks,
Harvey

[HarveyH]

Bump (IMG:style_emoticons/default/icon_bump.gif)

[Spoke]

What tests did you do the field test?

Did you try shorting D+ to DF coming from the alternator? This will make the alternator produce full voltage. Does the GEN light come on during this test?

What is the voltage of the D+/DF pins when shorted compared to the battery voltage?

[HarveyH]

Did the field test. At idle the voltage came up about 0.2V from engine off baseline. As RPM increases voltage at battery increases, stopped increasing engine speed at about 3100/3200 RPM, at that RPM voltage at the battery ran about 16.2V.

Didn't try {D+ DF} to ground, I'll check it this evening

My DVM is a Sears autoranging unit with a single AC/DC Volts selection and I can get only get the DC component to show.

Harvey

[plas76targa]

Did the field test. At idle the voltage came up about 0.2V from engine off baseline. As RPM increases voltage at battery increases, stopped increasing engine speed at about 3100/3200 RPM, at that RPM voltage at the battery ran about 16.2V.

Didn't try {D+ DF} to ground, I'll check it this evening

My DVM is a Sears autoranging unit with a single AC/DC Volts selection and I can get only get the DC component to show.

Harvey

Check your ground strap to the transmission? I had similar problems several years ago shortly after purchasing my car. tried regulators, cleaned the grounds as best i could, pulled the alt and had it tested, no improvement. Some one here suggested replacing the relay board, I did and problem went away. clean the contacts on the relay board or replace. hope this helps.

[HarveyH]

OK,
Got a bad cold and didn’t feel like working on the car much. I did clean the Relay Board and solder all of the contacts. Transmission to body strap is good.

What I’ve found today:
D- to Ground: Less than 0.1 ohm. Tried with meter polarized in both directions to make sure there was no diode effect.

D+ jumpered to DF, engine at idle: 18V from jumper wire to Ground

There is a notable AC component on the output to the battery. The DVM I have isn’t able to give an accurate measurement, but there is a moving bar graph type display on the bottom of the screen and it goes up and down erratically. Seems to be fairly high peaks involved.