Voltage regulator sends a current to the alternator to tell alternator how much voltage to output.

Check the alternator and voltage regulator grounds.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Had a bit of time this morning, so first thing I did was test battery voltage 12.56V. Then pulled the green field wire off the alternator and started it. Tested voltage across battery terminals 11.85V, so no ground short in the alternator. Plugged green field wire back in and got almost 19V, then pulled Voltage Regulator wire, and Volts dropped back to 11.85V.

Cleaned the VR grounds but they all looked good and tight, so I went ahead and replaced the Voltage Regulator with the original. Started the car and now have 15.1V with fast idle. Still a bit high, but I will get a new VR and see how it goes.

Found this upon further inspection of relatively new Voltage Regulator:

Installed a new Voltage Regulator and get the same 15.1 V reading while engine is running.

I better start checking all the connections and negative grounds... Can the ballast resistor affect it at all?

If the battery is a bit low on charge or if not run long, 15.1 V may be OK. Top off the charge on the battery with a separate charger, or switch to another known good and fully charged battery, then check again. After starting engine, you may have let it run/charge for several min for the voltage to come down.

Lou

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Home of Slant6-powered fun machines since 1988

Where are you measuring the voltage? It is possible that the voltage right off the alternator may be higher than other places in the system.
Does the voltage skyrocket when you rev the engine? If not, then I agree with what Lou just said, it may be 'normal' on your car.
-Matt

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-MattMan
LEANED & MEAN

I tried two different batteries which were fully charged with a bosch smart charger, one battery a year old and the other brand new. Same reading for both across terminals when running, as well as from the positive alternator output terminal and various grounds.

The newest Voltage regulator is actually showing 15.36 V. Seems a bit high, won't high voltage roast all the gauges at some point? Maybe blow up the battery again...

Must be some resistance through a poor connection somewhere.

You have to check for a voltage drop between the batt. post on the starter relay, and the blue ign. regulated voltage wire that runs to the alt., ballast or (?) ign., and the reg............any of the connections from both bulkhead pass-throughs, ign. sw. & connectors etc. have to be checked for a drop. If the reg. is seeing 14V at the blue wire, but the batt. is at 16~18V, it's not going to stop charging at that rate.

First, my apologies for reopening an old thread, but I didn't want to start a new one...

“You can do it quickly and cheaply by running two 10ga wires with ring terminals at each end directly from the alternator's output terminal to the battery + terminal. Each of these 10ga wires must have two 50A fuses, one located within inches of the alternator output terminal and the other located within inches of the battery + terminal.”

Okay, this makes sense. Questions now... I’m finally ready to do this thing...

1) Ring terminals and fuses — any suggestions for specific parts (e.g. fuse holders)? I'm at a loss. For the fuse, are we talking about something like this?, with one lead at a ring terminal and the other connected to the 10 gauge cable? https://amzn.to/2LwEDVV or illustration 2) Any pics from someone who has done this?

3) Just confirming, the alternator terminal is the one that's marked "output" in this image... 4) How do you feel about this advice from Dan’s favorite maven [cough], Rick Ehrenberg? https://www.allpar.com/history/mopar/electrical.html #5 — “Connect a fusible link to the starter relay stud. Crimp-splice in a piece of suitable (heavy-gauge) wire, and connect the other end to the alternator stud. That’s it....firewall problems bypassed forever!” (I assume it's one end to the output stud above, and one end to the positive end of the starter relay. Guess the ignition switch still works by interrupting the ground?)

Is the Ehrenberg thing basically doing the same as Dan’s, only instead of going to the battery, you go to the starter and rely on the big heavy battery-to-starter cable for the rest of the way?

I used to be a lot more adventurous but not so much now...

Yep.
Yep.
For very little extra money and effort you can do a whole-assed job of it.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

My one big question then is how I connect to the battery terminal... what kind of fastener?

Ring terminal/nut.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Sorry for my long delay. I ended up getting the summer flu...

I can't figure out how the ring terminal/nut would attach to the battery terminal. The battery-to-starter cable doesn't have any attachment points at the battery. I can see why Rick E. thought it made sense to run from the alternator output to the starter — it avoids the problem of hooking up to the battery, and the wire is less noticeable (for those who raise their hood during shows).

Er…what's not to figure out? Look at your battery cables where they attach to the battery itself. See how they clamp onto the battery with a bolt and a nut? You remove the nut, put the ring terminal on the bolt, and replace the nut thus holding the ring terminal to the battery terminal.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

A photo would be worth 300 words, I suspect... oh, wait, I get it, I think. We attach to the nut and bolt that are used to tighten or loosen the battery cable "end clamp" ?

Yes.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.