Voltage trouble

[71swngr]

The last time I was driving the car I noticed my voltage decreasing from 12-13 to around 10 by days end. I stopped and turned off the motor, short time later I tried to start the engine and it was dead. Got a jump and got it home ok. I changed the Voltage regulator a couple months ago, got a new battery and alternator (75 amp, 2 wire) installed them this weekend. The voltage is now back to 12-13 no higher, However when I put on the directional the gage fluctuates from 10-12 each time it blinks. When I turn on the headlights drops immediately to 10. The voltage gage is an Auto meter. Funny though the stock gage on the dash is consistent on the charge side and does not seem to be affected by the lights or directional. I'm thinking it bad wire, not sure, any thoughts would help.

Electric fuel pump
Electric Fan
MSD ignition
1971 340

 

[rrvolare]

What is amp output at alt battery cable with system loaded ( defogger, radio etc.... turned ON ) , at idle and at 2000 rpm ...

 

[71swngr]

I'll need to get a meter and check it out. Today voltage was 13-14, all seemed great. But again with the headlights on voltage was 10 at idle ~12 at a cruising speed.

 

[nothingbutdarts]

I'll need to get a meter and check it out. Today voltage was 13-14, all seemed great. But again with the headlights on voltage was 10 at idle ~12 at a cruising speed.

Contradicting yourself here a little. You are saying today it was 13v-14v with no load on the charging syst. other than the ign. system, then you turned on the headlights and it was down to 10v. @ idle & 12 volts cruising???

You might have a bad regulator still or a bad wire in the syst.

Voltage @ battery/charge wire on the alt. with the car not running?

Voltage @ one of the field terminals not running with key on?

Voltage @ the other field terminal not running with key on?

Do you have access to a 75a. to 100a ammeter? You should put it in series on the alt. output wire and run the engine & check the output however voltage will tell you if it's charging or not.

 

[srduster340]

On my '71 Duster I found rusty corroded connections on the alternator field wire plugs . I replaced the plugs and problem solved. The 2 field wires run to the voltage regulator if you didn't know.

 

[71swngr]

Yes, Today the Voltage fluctuated somewhat between 12-14v during normal driving. I have an electric fuel pump, electric fan and MSD ign. With the headlights on, same driving conditions, the voltage dropped to around 10-12v. Lower volts at lower rpm and higher volts at higher rpm. Is this normal fluctuation?

 

[71swngr]

On my '71 Duster I found rusty corroded connections on the alternator field wire plugs . I replaced the plugs and problem solved. The 2 field wires run to the voltage regulator if you didn't know.

Conections were pretty rusted. I replaced the connectors when I did the alternator.