Charging issues

So on my 61 ford falcon I just switched over from a generator to an alternator from a 70s chevy and I reran all my wires for it but it won't charge the battery but will keep the car running if I take the battery cable off so now I'm kinda stuck in a rut. I've been told to check my wiring and make sure that's right and it is but it still does the same thing any suggestions?


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Is it an internally regulated alternator, or external?

 

Don't disconnect the battery while it is running. There are three wires on that alternator. One is the big one, that runs back to the battery. Where did you attach the other two?

 

It is internally regulated . I have two wires on it from the little clip one of them goes to the back of the alternator labeled battery then on the same terminal I have it running to the positive on the battery and the other wire is running to the ignition switch


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Is it using a resistance wire to excite it?

 

I'm not sure I know what that is?


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And I'm not sure you got it wired correctly from your description either. But, assuming you do have it wired right, check your belt tension. It may be slipping.

Jack E/NJ

 

What is the voltage at the battery, running, and not running?

 

I Checked the belt tension that's fine so I don't know what's up with it I still have the old voltage regulator on it and can't figure out how to eliminate that and still have the car run


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Running its at 12.7 and same with when it's off but when I turn the lights on and put a draw on it it just drops and I watched it dropped till it got to 11 volts


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With the engine not running and the switch on, you should have battery voltage on the "battery" terminal where you have the wire connected directly to the battery, and on the smaller terminal farthest away from the "battery" terminal. The third wire, (guessing the one you have connnected to the ignition switch) needs to be less than battery voltage - somewhere between 4 and 8 volts will do. On some cars, this was done through the idiot light; other cars the actual wire itself is a resistor wire or there is a resistor somewhere in the circuit.

Some John Deere tractors (later 4020's that are 12V) used what they call an acorn resistor to accomplish the drop. One wire alternators have this resistor built in.

If you don't have the drop, it won't charge correctly.

And there's the obvious: Has the alternator been tested to verify that it works?

 

Okay I will have to look at that then cause there is no resistor on it do you know if they sell resistor wire and I can try that tomorrow


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It is not charging. Running, it should show over 13V. It is either not being properly excited, or it is broken.

 

I ran all new wires to hook it up and today I went to take the old regulator out and when I disconnected the wire that went to the starter selenoid it wouldn't turn over


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look here alt wiring
http://www.blert.net/comet/gen2alt/
http://www.wiring-wizard.com/Diagrams/gen2alt.jpg

 

Yours is like the upper half of the diagram.

The wire that went to the B terminal on your regulator should now go to the BAT terminal on your new alternator. Your horn wire attaches there too. If there are/were any other wires on the A terminal, they ALL need to go on the BAT terminal on the GM alternator. Connect the small yellow-black wire that was on the A terminal to the lead on the alternator plug that is NOT attached to the BAT terminal along with the fat wire back to the battery (terminal 1, closest to the BAT terminal.) Connect terminal 2 on the GM alternator to the BAT terminal. The rest of the wires in the original setup should be unnecessary.