What year did Mopar switch to dual field alternators

[Ghoste]

And what happens if you only hook up one field, undercharging correct?

[Nacho-RT74]

69s was a crossover year, being available on lates C bodies

then 70s gots dual fields but still roundbacks, up to 71.

72 was the first year for squarebacks


if you hook the only field from earlier installations on dual field alt, will need just to ground the field you are not wiring

couple of solutions for these.

-terminal and a wire to ground
-replace the isolation washer on brush prong for a metallic washer. This makes a cleaner view on engine bay... Advice: cut the prong you are grounding to not hook the wire there by mistake, or will short out the system when ign key in RUN

[Ghoste]

Other way around, if the wiring harness and  charging system call for a dual field but you install a single field alternator, then it undercharges?  Sorry I wasn`t clear there.

[Nacho-RT74]

Depending of alt.

Some "single fields" alts are disposed to set it in both situations ( ie, last 69s and 70s ) with just the propper brush and isolators intallation.

IF NOT, you can drill a hole of the size of the isolator on the blank space of brushes location ( opposite to the grounded brush mounted directly to housing ) and bolt there the isolator and brush

[Nacho-RT74]

here is the process of how to modify an originally designed single field to convert it on a dual field

these are pics I have collected allong the years, notes added by me.

I personally bought an originally born single field converted to dual field once maybe by some dealer or rebuilt shop locally

[Ghoste]

Okay thanks.  But if they are running a single field alternator in a car that is wired for a dual, it will be undercharging right

[Nacho-RT74]

you can make it work, feeding the single prong with blue wire BUT WILL GET MAX OUTPUT, NON REGULATED... you'll be full feeding the alt.


this is how it works both systems:

lates charges regulating negative ( green ) and positive being constant ( blue )

earliers charge with negative being constant ( grounded brush ) and positive being regulated ( green )

In both setups, green is regulated source BUT different pole/field

here is an exaple of an alt served from factory to dual purpouse

[Ghoste]

Okay, sorry for the confusion.  I`m trying to help somebody else with this.  What they are seeing as a low charge is in actuality no charge at all but on the ammeter in the dash it all looks the same so that makes sense now.

[Nacho-RT74]

if there is not difference on ammeter reading with engine off and engine on on charge status, it is definitelly a NON CHARGE status.

if the needle moves a little bit to center on a discharge reading, from engine off to engine on, then you have a LOW CHARGE status.

EVERYTHING OF THESE IS FOR REAL, if you have the sources being feeded from the RIGHT side of the amm ( no one accesory being feeded from batt )

you won't have any ammeter reading ( nor charge or discharge ) if feeding from batt any accesory with engine off. With engine on, you can get a charge reading which is not actuallt a charge readin, like really the alternator feeding teh accesories on batt side of the system ( another reason why ammeter are being stressed unnecesarily )

sorry all the extra info, but if you understand how to read the ammeter, will understand everything

[Ghoste]

I'm probably just misunderstanding you (sorry I'm slow with electrical) but on my car if the engine is on, the needle will be slightly right of center.  If the engine is off, my car will have it centered.  If the engine is off and I use any accesory whatsoever, even just opening the door and triggering the courtesy lights, the meter moves to the left.

[Nacho-RT74]

the more centered the needle is ( and keeps ) with engine on, more healthy your charging system is. Normally if you get, have after crank the engine and get it running, the needle toward to right, will be recharging what batt lost on cranking process, untill get it centered alone. Depending on alternator capacity, engine RPMs and the car use, can take afew seconds, afew minutes or all day long LOL.

Engine off, and open doors will read discharge by dome and courtesy lights, put the key in RUN will get more discharge by the ignition system, choke, etc... If reading remains exactly the same after start the engine, Alt is not charging. If reading moves to center, no matter if still slightly on discharge side or right onto the center, or fully moves to charge side, is obviouslly charging. Maybe low charge but charging. Will depend of alt output capacity &/or conditions and RPMs.

more here:

http://www.dodgecharger.com/forum/index.php/topic,33574.0.html

[Ghoste]

My own is fine, get this other guy sorted out and all will be well.  Thanks.

[grizparker]

if you hook the only field from earlier installations on dual field alt, will need just to ground the field you are not wiring

couple of solutions for these.

-terminal and a wire to ground
-replace the isolation washer on brush prong for a metallic washer. This makes a cleaner view on engine bay... Advice: cut the prong you are grounding to not hook the wire there by mistake, or will short out the system when ign key in RUN

So, I've got a dual field alt 65 Amp.  Right now I've got the a cable on the battery post and on one of the FLD tabs.  The other FLD tab is sitting there empty.  I measured my voltage this morning, and I'm only getting from the alternator 11.8 volts when at idle.  Should I be doing something with that secondary FLD tab?  I thought I've read somewhere to loop it back to the Battery post on the alt to get full power.  Not sure though...

[Nacho-RT74]

ground it as I explained on what you quoted from me. Actually you are measuring the batt voltage at alt post, not really any alt output