Weird overcharging issue

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Belvedere66

Belvedere66

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Hey all, I have suspected my regulator box is bad but I wanted to get some opinions before I start buying things. About a month ago my car started acting funny.....every couple cold starts (not every time) my voltage gauge would read excessive charging and then after a bit would go to normal. Twice now in this past month I have been driving and randomly my radio fuse blows due to a excessive charge spike. The alternator is less than a year old but I haven't really touched any of the other components because why replace what isn't broken, right? Since this is a recent issue I suspect something is just wearing out. It only spikes when the RPMs are increased as well, at idle it isn't really noticeable.
 
Sounds like it is going full field. However more info is needed. Style of alternator and regulator, current wiring configuration and any upgrades to it? Engine and chassis grounds etc...
 
What are we working on, and what do you have for a regulator? If this is the old mechanical (69 and earlier) I'd replace it.

If it's 70 / later (isolated field) you might have the green connected brush holder grounding intermittently, or the green wire might be going to ground some place in the harness. And, certainly could be a bad regulator

However, is it actually OVER voltage or just showing a lot of charge on the ammeter? Could be that it's been "dropping out" and then suddenly cuts in and tries to make up. Put a voltmeter on it and see what it's actually doing.
 
The giveaway on over charging is a boiling battery that stinks of hydrogen gas. That is usually a sign you are a bit late in detecting the problem and the battery is toast though.....
 
It's a 71 Dart, bone stock wiring and charging system. Engine is a '75 block 360 but all components in the electrical system are the original style.

Yeah it is showing it on the ammeter, it doesn't show any drop that's measurable, it hasn't done it in probably a week now. I will check the path of the green wire and see if anything is out of the ordinary. Since it is so intermittent I want to lean towards something grounding out.
 
If there is a voltage drop from battery to blue wire at regulator IGN, voltage will be high at battery. That usually happens with poor bulkhead connection. However since you are reading ammeter, not battery voltage, and IGN voltage, nobody will know for sure. The other possibility is poor ground at regulator mount. A poor connection at green wire will result in under voltage, not over voltage. The early regulator momentarily switches the green wire to energize the alternator field. If the regulator contacts are stuck, or green wire is shorted to 12V, then full field and over voltage will result.
 
if it is the '70 up system (no wire would resistors on bottom of reg) then (1) check that the reg is grounded to the firewall (pull it & scuff both reg/firewall) and (2) check the brushes in the alt for looseness/anything improperly touching that you can see (30 what Del said, the green field wire needs no loose connections/terminals on either end of it (as he said might be going open/closed). It ain't the reg (if it is electronic (no resistors) cuz when they go bad (open or FF) they stay that way. if its a wire wound "box" reg definitely replace it ASAP. As you know FF will fry stuff fast/does alot of system damage. also might be a part time open in the alt. EDIT clean bulkhead also
 
In addition to above, as I eluded to earlier, you want to try to determine if it is working "somewhat normally" and then suddenly overcharging, or is it dropping off, allowing the battery to go down some, and then suddenly "kicking back in?"

Some other things.......

Remove VR, scrape around the mounting and remount. Make CERTAIN it is grounded, and mounted tight

Remove and inspect the VR connector. "Work" it in and out several times to scrub the terminals clean and to "feel" for tightness

Might be brushes are worn, sticky, dirty, cutting in / out

'Rig' a voltmeter in the car so you can monitor voltage, both when seemingly normal and during the "high" spike.

Read the MAD article, even if you don't do that modification. It gives a great overview of how the system works and problems inherent in these girls

http://www.madelectrical.com/electricaltech/amp-gauges.shtml

Check the belt condition and tightness

I would remove the bulkhead connector plug sections and inspect them after reading the article above
 
Just had this problem on 70 duster.It was a bad connection at the bulk head blue wire going to alt.Look inside the car at the back of the bulk head connector and see if you have any melted wires.Have someone get on the other side and push the connectors together to get better connections.You may have to splice the wiring and bypass the bulk head connector.
 
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