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Discussion Starter #1
I have a 1968 that has been restored and I am just getting it back on the road. Everything was out of this car in the process except for interior/dash. I put the original wiring harness back in and the drive train set up was in the car before and running good. My problem is that my battery will not charge. With the car off I get 12.8 volts at the battery and with it running I get 12.4 volts at the battery. At the alternator I get 15-20 volts from the battery terminal..I assume it fluxuates due to my choppy idle/cam. I have replaced the regulator with no change. I cleaned all grounds and the two connections on the junction block behind the battery. The car runs great until the battery goes after a day or so . I have also swapped alternatores with no change in voltage. I have checked for leaks and found none. I am going on Power tour in 2 days and am at my wits end! Thanks.
 

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Voltage from the alternator is to high. Almost sounds like open circuit voltage (no load on the alternator) Bet ther is an open between the alternator output terminal and the main power feed terminal on the horn relay.

Is the red charging wire that runs across the radiator support from the terminal in front of the battery connected to the big terminal on the horn relay? What is the voltage at the horn relay end of the red wire? This is also where the Alternator output is connedcted so if it's not alternator voltage then then perhaps the fusible link is blown between the alternator output wire and the horn relay.
 

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Discussion Starter #3
I wish I were at home right now to answer this. Where is the fusable link located? Are these the black rubber cyliders that are visable very close to the horn relay and regulator or are they buried in the harness?
 

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Sounds like them, there is one near the horn relay with 3 red wires attached together, the one from the alternator, the one to the battery terminal, and one to the voltage regulator. On s 69 there are two of them, one is about 2" from the voltage regulator connector, the other is back a couple of inches buried under the tape.
 

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Discussion Starter #5
Well I had no luck in 6 hours of searching last night. I get battery voltage (12.5V) at the horn relay which I assume means the fusable links behind the battery and to the horn relay are good. For the fusable link that comes out of the passenger side terminal at the horn relay, I did a continuity test since I did not know where that ended up going. That test showed continuity...but can the fusable link still be bad since that is a very low voltage test?
I also have good continuity tests from the F and R connections at the alternator to the F and #2 plugs at the regulator. I have a good continuity test from the Bat. terminal at the alternator to the #3 plug at the regulator.
I ran a test that was outlined in a manual that involved putting the voltmeter between the alternator F teminal and the positive battery terminal and tuning the ignition on without starting the engine. I read 7.4 volts. It then said to clean all connections, which I did again and no change?? If I run the same test to the R terminal I get battery voltage.
LAst thing I did was to jump from the F alternator plug to the + batt terminal and I got the batt voltage to get up to 13.4 volts. By this time my battery probably did not have a full charge.
Can this be something due to the circut that goes to the ignition? Coincidentaly I have a gas gauge that just pegs at way over full? Can the horn relay go bad in any way? I am really grasping at straws at this point.
 

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just a suggestion but make sure the positive terminal of your battery is hooked to your starter and the neg. side goes to the engine. if reversed i don't think the alternator could charge through the zener(sp) diodes. because you would have a reverse polarity situation.
 

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Make sure the F connector on the alternator (closest to the passenger fender) has the blue wire connected to it, and the R connector (closest to the drivers side fender) has the white wire connected to it. The blue wire should also be on the voltage regulator terminal closest to the drivers fender, and the white wire (which gets spliced to an orange one) ends up on the second terminal on the voltage regulator right next to the blue wire.

When you got 12.5 Volts at the horn relay what was the voltage at the alternator output terminal (car has to be running)? If it wasn't 12.5 Volts plus a little then the wire that comes from the alternator to the horn relay terminal is open circuited.

The output wire from the alternator is spliced to the red wire that goes to the battery terminal, and the horn relay, as well as the main power feed to the fuse panel at a fusible link. It's possible that the fusible link blew and open circuited only the red wire from the alternator output terminal to the fusible link, while leaving the other three wires connected. Since you got voltage to increase to 13.4V by jumping the Field terminal to the battery, this wire shouldn't be open.

Maybe it's just a bad voltage regulator, or the voltage regulator isn't grounded. Make sure you get a good ground from the radiator support to the case of the regulator.
 

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Discussion Starter #8
With the car running the output at the battery terminal on the back of the alternator was 15-17 volts, but only 12.5 at the horn relay. I have used two regulators and two alternators with good ground with no change.
I just got off the phone with Mark at MADelectrical.com and he thinks I likely have a burned wire between the alternator output and the horn relay due to the condition mentioned above. My harness has likely been manipulated since I have a passenger side alternator. Could I jump the alternator output voltage to the horn relay or somewhere else for diagnostic purposes and for a tempoary fix?
 

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Yes, just run a Red number 10 AWG wire from the alternator to the same terminal on the Horn relay as the red wire from the positive battery terminal lands on. If your worried about the loss of the fusible link either buy one at NAPA rated at about 150% of your alternator rating (37A alternator = 50-55Amp fuseable link) or splice in a short length of #14AWG wire. Use a good heavyduty ring tongue terminal on the alternator end and a fork terminal on the horn relay end.

If you don't have the console mounted gauge setup you could actually land the #10 wire onto the terminal block infront of the battery. If you have the guages the ammeter will not work correctly unless you run the alternator output directly to the horn relay terminal.
 

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Wow, good info Mark.

I had converted to a one wire alternator a few years ago. My amp meter never works right . I have the typical setup with one wire from alternator to the block in front of the battery. Then a wire from there to the horn relay. I'll add a single wire directly from the alternator to the horn relay. How does the 'multi-stage' setup interfere with the gauge workings?

Thanks.
 

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Try these two links:

http://www.camaros.net/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=10;t=001606

http://www.camaros.net/cgi-bin/forum/ultimatebb.cgi?ubb=get_topic;f=10;t=001615

The ammeter is nothing but a millivolt meter that measures the voltage drop across the 10AWG charging wire that runs across the front of the radiator support between the horn relay and the terminal block infront of the battery. All it indicates is if the battery is being charged, or discharged, not what the alternator puts out.
 

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Good reading. I don't understand your earlier comment, though, about console gauge workings and needing to run one wire from the alternator to the horn relay for proper function.
 

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Discussion Starter #13
Follow up...
On a whim I bought a second regulator on my way home and hooked it up before I went any further. Fixed the problem. The first regulator was bad out of the box. It is hard to keep that in mind somentimes that new parts don't always mean good parts.
Anyway, Thanks for all the help and Power tour was a blast, despite some rain at the end.
 

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Originally posted by RickD:
Good reading. I don't understand your earlier comment, though, about console gauge workings and needing to run one wire from the alternator to the horn relay for proper function.
Because the ammeter (millivolt meter) uses the red wire (charging wire) that runs from the horn relay to the battery as an external meter shunt. It measures the voltage drop and polarity of that drop to determine if the battery is being charged or discharged. If the voltage is higher on the horn relay end of the wire then the battery is being charged, and the meter will deflect to the right of center. If the battery end of the cable has a higher voltage then the battery is being discharged and the meter will deflect to the left of center.

Normally the alternator output is sent to the same terminal on the horn relay that the charging wire lands on. But there is also the main power feed for the whole car on this terminal. The alternator provides all the power to the rest of the car, and if any is left over it flows thru the red charging wire and recharges the battery. If you run the alternator output directly to the battery, or to the starter terminal then the only way current can flow is from the battery to the rest of the car. You've essentiall wired the battery in series with the alternator output instead of in parallel to it as the original design called for. The battery voltage will always be higher than anyother point in the car (except at the output of the alternator) and the meter will always indicate a discharge.

Remember, the ammeter does not indicate how much current the alternator is putting out, but how much is being put into, or taken out of the battery. Alternator output is not important, it's either sufficient to supply your needs or not. Battery output is very important because if you always draw from the battery, someday it will be dead.
 

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Thanks, Mark!
 
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