HELP! charging system BLUES

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dazedduster

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73 Duster 360, At Idle The Charging System Shows 10 Volts And The Amp Gauge Shos In The Negitive When Driving It Shows 14 Volts And Positive In The Amp Guage. It Has New Alternator, Battery And Voltage Regulator.

Any Idea How To Fix It. You Can See The Lights Dim And The Windshield Wipers Will Stop Working At Idle Give It Some Gas And All Is Fine

Help
Thanks
 
Sounds like you have massiver resistance in a ground somewhere. Check ALL of your ground connections, as well as your primary charging connections. Where is your 10 volts being measured from?
 
What rpm is your idle? Sounds like you just have an alternator that is not putting out much at that rpm. Some are better than others at low rpm.
 
dont know rpm at idle but this is the 3rd altenator that done it(i had extras to try)
the 10 volt is measured off the iginition i belive, i'll double check the guage to make sure have to wait for a brake in the rain though
 
I would also check the terminal in the bulk head connector and make sure that they aren't corroded(sp). One thing that I would also do is bypass the ammeter. You will not be sorry for doing it. One day it will leave you stranded and that is the last thing you want to have to deal with on the side of the road.
 
Sounds normal for a Mopar- Idle speed does have a direct bearing on the amount of voltage to the system. Usually a smaller pully on the alt helps, up the idle speed a bit.

the old alt's only put out power starting around 1200 RPM's below that it can't put out a charge. some of the later alt's- smaller ones off 90's with arounds 75-90 amps with the smaller pully work well- but with 90 amps you better beef up the main power wiring and connectors!!!!!
 
Your battery should have a static charge of 12-12.5 volts so if you are seeing 10v anywhere in the system YOU HAVE A PROBLEM!!! A 2v drop between the battery and the ignition switch is way too much. You are just turning that current into heat somewhere. I agree that you had better take a look at your firewall connector. Also clean both ends of the positive battery cable, body ground, battery to block cable and engine to body ground points.

Now, with the engine running at fast idle, you should be getting 13.5v at the back of the alternator. You should be getting close to that at the battery as well. If you do bypass the ammeter (not a bad idea) you might want to consider bypassing its wiring through the firewall connector. Running at least a 10AWG wire from the alternator output post directly to the positive battery cable on the starter will suffice. If you plan to add high power headlights or a monster amplifier, you want to drive them from here too so their current does not have to go through the dash
 
10v at the coil should be about right due to the ballast resistor, assuming thats what you meant when you said you measured off the "ignition".
 
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