Sudden electrical spike, burning smell

[ChargerChad]

Driving my daughter to practice and very suddenly my ammeter spiked all the way past the “C” and we got a slight burning smell. Turned around and came back and my multimeter is showing 13.6 volts at the battery at idle and almost 17 volts at about 2000 rpm. Ammeter drops slightly at idle but pegs again with any rpm. I’m thinking my voltage regulator just sh*t the bed, but I’m no electrical guru so I wanted to bounce it off you guys first.

 

[threewood]

That's the first place I would look for an overcharge condition. What year car?

 

[fine69]

Did your daughter make it to practice?

 

[R413]

regulator needs a ground or it will go full Charge.

 

[beanhead]

Sounds like the regulator to me too. 'If it was me' just to be safe I'd crawl under the dash with a flashlight and do a good inspection of the wiring, especially at the bulkhead and ammeter terminal area. If you smelled it in the cabin, something got hot and could possibly have melted a little insulation which could put you at risk of a short in the future.

 

[Dave6T4]

Check the red and black wires to the ammeter.

 

[dadsbee]

Single field alternator... regulator points stuck.

Dual field .. blue wire off / broken.

 

[Fran Blacker]

I agree all said beanhead about looking at bulkhead and ammeter. I had ammeter burnout lucky it was at work and was cold. When inside went into maintenance dept. got wires and alligator chips hot wire car. Thought bulk connector took it out butt solder all the wires NOPE. Took dash apart (my first time)Ammeter terminal melted and was hanging in the breeze. Really check that!

 

[ChargerChad]

That's the first place I would look for an overcharge condition. What year car?

Sorry, 1971 Charger SE with 383. Original wiring.

 

[ChargerChad]

Did your daughter make it to practice?

Yeah, wife had to take her though

 

[RJRENTON]

regulator needs a ground or it will go full Charge.

INCORRECT......the Mopar electronic voltage regulator looses ground, the alternator will not charge, as it needs the ground to complete the internal switching transistor's circuit to ground. The alternator's field voltage varies from zero to ~ 6 volts DC, as controlled by the voltage regulator. The same applies to the old mechanical voltage regulator, it needs the ground to function, losing the ground results in a no charge condition.
BOB RENTON

 

[ChargerChad]

INCORRECT......the Mopar electronic voltage regulator looses ground, the alternator will not charge, as it needs the ground to complete the internal switching transistor's circuit to ground. The alternator's field voltage varies from zero to ~ 6 volts DC, as controlled by the voltage regulator. The same applies to the old mechanical voltage regulator, it needs the ground to function, losing the ground results in a no charge condition.
BOB RENTON

INCORRECT......the Mopar electronic voltage regulator looses ground, the alternator will not charge, as it needs the ground to complete the internal switching transistor's circuit to ground. The alternator's field voltage varies from zero to ~ 6 volts DC, as controlled by the voltage regulator. The same applies to the old mechanical voltage regulator, it needs the ground to function, losing the ground results in a no charge condition.
BOB RENTON

makes sense. I cleaned up the ground anyway and started it up. At first it seemed to be okay, showing 13.4 at the battery but then the engine pulled down like it was under a load and voltage spiked up up to 16.8 again. I ordered a new regulator from NAPA for pickup tomorrow. More to follow…

 

[ChargerChad]

Turns out NAPA had the regulator in stock. Plugged it in and at first seemed to be fixed then the voltage at the battery jumped to almost 18. I went to move my work light and saw sparks behind the alternator. Turns out the green field wire was shorting out. Took this piece out and butt-spliced and heat shrinked a new end in and problem solved:

 

[dadsbee]

That'll do it. Told ya to check the blue wire. Blue off = full charge. Green grounded out= full charge.

 

[ChargerChad]

That'll do it. Told ya to check the blue wire. Blue off = full charge. Green grounded out= full charge.

You were right!