Electrical Help

[DartGTDan]

My buddy has a '63 Dodge 440 with electrical issues. He believes he keeps "blowing" voltage regulators when he turns on the headlamps. Daytime driving he thinks it's all good.

He's replaced Voltage Regulators ~5 times that I am aware of (with both mechanical & electronic style). The alternator was replaced 2 years ago (O'Reillys).

Today the engine was warmed up and I made some voltage readings. Engine off the battery voltage was 12.5V. Engine idling in PARK battery was 12.25V, Alternator stud was 11.9ish Volts & the blue wire on the Voltage Regulator was 11.7ish Volts. Idling up the engine did not change the readings significantly.

He's got another alternator that will be going on tomorrow. But we're unsure where to begin. How do we know if a VR is "blown". Wouldn't a bad VR eventually kill (or boil) the battery? Wouldn't the alternator make the battery voltage increase, to 14V, when the car is running?

I'm at a loss.

 

[1969383S]

Check resistance on all the charging wires! Most likely an old old tired wire issue!

 

[Dana67Dart]

@Mattax has posted some really good diagrams lately that show the charging system and others. Just the other day some one posted about blowing VRs some of the info is in there

 

[Mattax]

My buddy has a '63 Dodge 440 with electrical issues. He believes he keeps "blowing" voltage regulators when he turns on the headlamps. Daytime driving he thinks it's all good.

He's replaced Voltage Regulators ~5 times that I am aware of (with both mechanical & electronic style). The alternator was replaced 2 years ago (O'Reillys).

Today the engine was warmed up and I made some voltage readings. Engine off the battery voltage was 12.5V. Engine idling in PARK battery was 12.25V, Alternator stud was 11.9ish Volts & the blue wire on the Voltage Regulator was 11.7ish Volts. Idling up the engine did not change the readings significantly.

He's got another alternator that will be going on tomorrow. But we're unsure where to begin. How do we know if a VR is "blown". Wouldn't a bad VR eventually kill (or boil) the battery? Wouldn't the alternator make the battery voltage increase, to 14V, when the car is running?

I'm at a loss.

You're thinking correctly. The alternator will bring bring system voltage up. All of those wires should be at the same voltage.
The regulator can fail a few different ways. it can fail open - then there's no charging or it could provide max current all the time - that would result in high voltage and yes could boil the battery etc.
You could use the Voltmeter to see if the regulator is allowing power through.
Or you can jumper the regulator feed and out terminals together to allow a direct connection to the rotor. If the alternator still doesn't produce power then the problem is in the alternator.

Seems like there's some resistance in the wiring, but that's not the charging issue.
If you can - recharge the battery on a slow charger before doing more tests.
Yes the recent thread about mechanical voltage regulator may help you get going. This booklet is really good for how the system works.
Alternators and Regulators (Session 228) from the Master Technician's Service Conference
Save all the old parts. Some may be fixable. And fixed they may be better than 'rebuilt'.
Alternator brushes are easy. Other stuff on Roundback alternators requires a bit more skill to fix but diagnoses can be done for open circuits pretty easy.
Some photos in here.
Alternator repair, a little show and tell.

 

[Oldmanmopar]

Check your engine to body ground. Also check the voltage regulator ground. If the car has been converted to electronic ignition there is a different VR needed.

I would change it over to dual field alt. The car will charge at idle and at RPM's the early style single field does not. That is the reason most 69 on back cars headlights go dim at idle and get brighter when on throttle. 70 on up dual field does not do that.