questions about battery disconnect wiring
If going with an anlternator with internal regulator and single wire, crackedback's approach probably makes more sense.
The one here retains more original wiring layout and works with an external regulator. It only kills the big wire from the battery to starter from the kill switch in the trunk.
This is all factory wiring.
The wires in the center are joined by welded junction.
R6 is power from the alternator.\
Power to/from the battery goes through the ammeter.
J1 feeds the Key Switch
Q3 feeds the fuses that are always hot
L1 feeds the headlight portion of the headlight switch.
S2 triggers the starter relay
J2 powers the ignition when the key is in run. It also powers the alternator field, along with choke assist and carb solenoid if present.
Keeping it to the same drawing.
When the key is in RUN.
J2 is hot
As long as the master disconnect is closed, power flows through the 85 terminal to the 86 terminal causing the relay to close.
With the relay closed the ignition and field get power.
If either the key is off, or the master disconnect is off, then the relay is open. In either case power to run alternator and the ignition is cut.
(During start power for the ignition comes through the J3 wire not shown. '74 being a little more complicated because of the seat belt interlock)
The blue wire on the starter relay is a 16 gage fusible link, same as factory. That protects the 12 ga wires downstream of the battery if there is a short.
If you're actually going to go this route, there are some refinements I'd suggest depending on whether you want the ammeter to work.
But regardless the concept remains the same, as does the relay.
Basically this is an illustration of an approach that came out of discussion in a thread with @67Dart273.
If going with an anlternator with internal regulator and single wire, crackedback's approach probably makes more sense.
The one here retains more original wiring layout and works with an external regulator. It only kills the big wire from the battery to starter from the kill switch in the trunk.
yes. Headlight switch.
This is all factory wiring.
The wires in the center are joined by welded junction.
R6 is power from the alternator.\
Power to/from the battery goes through the ammeter.
J1 feeds the Key Switch
Q3 feeds the fuses that are always hot
L1 feeds the headlight portion of the headlight switch.
S2 triggers the starter relay
J2 powers the ignition when the key is in run. It also powers the alternator field, along with choke assist and carb solenoid if present.
This is the same type of relay as you might use for headlights. Its only going to carry 5 or 6 amps if using an older alternator and ignition, maybe as much as 12 amps at top rpm if using an MSD and a newer alternator with higher field draw.
Keeping it to the same drawing.
When the key is in RUN.
J2 is hot
As long as the master disconnect is closed, power flows through the 85 terminal to the 86 terminal causing the relay to close.
With the relay closed the ignition and field get power.
If either the key is off, or the master disconnect is off, then the relay is open. In either case power to run alternator and the ignition is cut.
(During start power for the ignition comes through the J3 wire not shown. '74 being a little more complicated because of the seat belt interlock)
The blue wire on the starter relay is a 16 gage fusible link, same as factory. That protects the 12 ga wires downstream of the battery if there is a short.
If you're actually going to go this route, there are some refinements I'd suggest depending on whether you want the ammeter to work.
But regardless the concept remains the same, as does the relay.
