Low Charging Voltage

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terry

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Hi Folks Car Has Run Great For 4 Years And Volts Gauge Held Steady At 13.5 Volts,
Then About A Month Ago The Volt Gauge Started To Bounce Between 12 And 14 Volts. Then It Stablized At About 12 And Stayed. I Have Replace The Alternator 3 Times And Voltage Reulator Twice.no Help Either Time.
This Is On A 68 Barracuda With The Upgraded Electronics. My Battery Is In The Trunk And When The Car Is Running I Measure 11.7 Volts. The Battery Was Tested Today By My Local Autozone And Proved To Be Good. There Are Times When It Won't Start But If I Put On A New Voltage Regulator It Will Fire Right Up.but Stll 11.7 Volts.about The Only Thing I See Unusual Is When I Try To Start The Car The Volt Gauge Goes To Zero. I Have Gounded Everything Twice. Ballest Resister Maybe?
Any Idea's?
Thanks Terry
 
Terry,

How about the ground for the voltage regulator? They ground through the case and corrosion or paint can cause low voltage problems.
 
Ramcharger
I Have Ground Off The Paint On Both The Firewall And Any Of The Regulators I Have Tried. I Have Even Run A Braided Ground Wire From One Of The Attaching Screws To The Master Cylinder Bolts
Terry
 
hi terry, check the voltage on the field terminals on the back of the alternator. one should be about 12 volts and the other should be less say 4-5 volts. If you have zero volts on one or more of the terminals you will want to make sure that you have +12v to the "I" terminal of the regualtor. here is a pic to help you along

latecharge-1.gif
 
Sedan
Ok , With The Car Off And Ign. Switch On I Measured The Blue Wire To The Alt.field And Got 11.11 Volts, The Green Field Wire 1.32 Volts. I Again Measured The Blue Wire Which Goes To The I At The Regulator And Measured 12.04 Volts.
???????
Terry
 
Welcome to my hell. Trying to find a good regulator has been like looking for a needle in a haystack.
 
If you remove the green wire on the alternator and short that alternator terminal to ground the voltage across the battery should go to 15+ volts and higher as the rpm increases. If that happens then you have a good alternator. If it doesn't then make the same measurement to ground from the output terminal of the alternator if you get the 15+ there then you have bad connections between the alternator and the battery. If you don't then the alternator is bad.

The blue wire on the alternator when removed from the field terminal and the key in the run position should measure within 1/2 a volt of what the battery voltage reads. If it doesn't you have bad connections some where. The green wire on the alternator makes a connection to ground through the regulator body. With the key in the run position and the engine not running the resistance from the terminal on the wire at the alternator to ground should be within an ohm of zero. If its not you have a bad ground connection at the regulator or a bad regulator.

I would make sure all your ground connections are good. If you don't have them I would add a ground strap or two between the block and the body. I would also use toothed star washers under the fasteners holding the regulator and ground cables.
 
thanks for all your help folks. problem fixed ! turned out to be my moroso battery switch i have located by my tail light. it was the terminal in which the wire runs to my alternator. i had noticed that the wire was loose a week ago so i just tightened it up. but once i finally ran out of idea's i disconnected the wire off the battery terminal on the alternator that runs to the switch and connected the orginal wire in the harness back up to it and bang. 13.5 volts. i tried a jumper wire hopping it was the wire and not the switch but same bad results.
terry
 
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