Need wiring info for installing a duel field alt.

[DaytonaJim]

I installed a duel field alt years ago when I put electronic ignition in my Daytona. I ran the second field terminal to the 12V side of the ballast resistor. Now I'm told that is not the way to do it. Any wiring diagrams out there?

[elacruze]

I'm sure somebody will come up with the 'stock' wiring diagram.

If you're only concerned with function, then theoretically the field should be attached as directly to the battery as possible. Of course, the power must be switched to avoid a possible drain while not running. The battery is the requirement for voltage; to charge a 12v battery you need about 14.5 volts. The other components in the system can use a range of voltage, usually from 9-18v without damage. This is only important when you have poor connections between the alternator field and battery; every drop in voltage reports back to the regulator. If the regulator sees battery voltage minus 1 volt, it will eventually attempt to charge the battery higher by 1 volt, which will lead to boiling the battery.
It's not critical where you source power from, only that it's switched and that the voltage shown to the regulator is closer than 1/2volt to the actual battery voltage.

If that's not clear, let me know.

[Chryco Psycho]

are you running the 70 up electronic regulator ? you have to with the dual field .
!2v power from the ballast is is fine you need 12v to the field terminal & the voltage reg then connect a wire [green from the factory ] between the second field terminal & the second terminal on the regulator . The feild is grounded through the regulator to ground , up to 69 they switched the power to the field not the ground

[Nacho-RT74]

it is how you did, HOWEVER, being more specifical to let you know what are you doing with that job:

"single" to "dual" field conversion diagram

( and one quote of another thread I posted about how they work )

earlier alts setups got one brush directly bolted to chassis ( grounded ) and one isolated. Which ever brush you test for continuity, will test CONTINUITY with chassis, even the isolated one due is being allways making contact with the non isolated one throught the rotor. True, won't give you 0 ohms, but maybe 8 to 12 ohms which is the rotor resistance.

earliers setups alts ( with mech regs, or same setup with modern electronics inside ) gets constant ground through the grounded brush, and the isolated brush will get a positive pulsating signal ( produced by the mech reg, like a relay ) or "regulated" which is what changes the magnetic field intensity inside changing of course the output from alt as required.

Lates setup is a diff story. They get positive constant from the key, and regulated negative or ground from regulator. Thats why on lates they get both brushes isolated. Positive brush needing of course to be isolated from ground, and negative brush needing also to be isolated being this now the regulated source.

On both setups the GREEN WIRE is the regulated source, positive en earliers, and negative on laters

If you full fill both brushes fields with each signal ( which means bypassing reg ), you should get full juice from alt

[Nacho-RT74]

on a "wider" view