12v wiring diagram

D

dbrist

Junior Member
I've been searching these threads for a while and I might have missed it, but I was wondering if anyone had a 12v negative ground wiring diagram
 
No but in the Model A For Mechanics Handbook Vol. 2 shows it all.
 

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Only difference between 6V positive ground schematic and 12V negative ground schematic is the polarity of the battery. Just have to repolarize the generator after changing the battery connections if you are going to use the same generator. Make sure you have negative ground alternator if using an alternator. The electrons do not care which way they travel. They just move from negative to positive.
 
dbrist said:
I've been searching these threads for a while and I might have missed it, but I was wondering if anyone had a 12v negative ground wiring diagram
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One only has to swap the wires on the ammeter and the coil to change the polarity.

To increase the voltage:

The coil needs to be changed or a ballast resistor added.
The horn needs a resistor or needs to be rewound.
Here is where we can get into a debate, one camp says leave the starter alone and the other says to have it converted to 12 volts. Take your pick.
Of course the bulbs have to be replaced.
 
Points are wired same as the battery. Whichever wire goes to ground from the battery goes to the points from the coil.
 
I just made a 12v Negative Ground diagram after rewiring mine. This is a tried and tested diagram. Here is how you wire the ignition system. This diagram does not include lighting and horn.

NOTE: The Aftermarket "pop-out" style ignition cable connects to the "ON" position of the key switch. The "OFF" Position of the key switch connects to the NEG side of the coil. The key switch simply completes that circuit. DO NOT supply the "pop out" cable with 12v+!! Also in this diagram, you are looking at the BACK of the Ammeter where the studs are located. This diagram shows a GM 10Si one wire alternator, which self excites. Make sure you have a alternator that excites at LOW Rpm or it will not charge at idle. If you run a 3-wire alternator, DO NOT supply 12v constant to the exciter while the car is off. It WILL burn up!
 

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30AModel,

You need to check your diagram as the ammeter is not connected and the alternator connects directly to the battery.

Marc
 
The ammeter is connected to the distribution block and the main alternator lead connects to the Positive post on the starter, which in turn feeds back to the battery.
 
Ammeter originally was wired to show only battery current in/out. 30AModel moved it to the load side; it shows only "charge" of the entire load (minus coil) from alternator and/or battery. (I suggest moving coil to other side of block so its current will register also.)
 
Am I wrong?? The ampmeter has to have current flowing through it, or else how would it register current? If one side isn’t connected to anything, I fail to see how it would measure the current.
 
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