One wire alt replacing a gen..wiring Q'ssss

[speed service]

Ok here is one for the "better than me at electrical group".... Have a buddy that replaced his stock gen in his Impala with a one wire alt....Now the gen light stays on.....How do we wire it to work with the alt !!
I told him to pull the bulb...I got a dirty look..thanks in advance for the help

Chuy

[joe_rocket45]

Re: One wire alt replacing a gen..wiring Q'ssss

good question, do you have a wiring diagram?

[CarPlayLB]

Re: One wire alt replacing a gen..wiring Q'ssss

Here is a long read that should clear this up for you

http://www.madelectrical.com/electricaltech/onewire-threewire.shtml

They make a lot of sense...and they don't sell alternators so they may be unbiased!

Did the car have the plastic plug with two wires going in to the old alternator? If so, plug it back in!

[squirrel]

Re: One wire alt replacing a gen..wiring Q'ssss

what type alternator did it have before? internal or external regulator?

and the whole point of the one wire alternator is that the idiot light gets disconnected and does not work.

so pull the bulb

[joe_rocket45]

Re: One wire alt replacing a gen..wiring Q'ssss

http://www.aaroncake.net/CIRCUITS/lowvolt.asp

[speed service]

Re: One wire alt replacing a gen..wiring Q'ssss

Squirrel....He's going from a gen to a 1 wire alt....Joe thanks for the info.. I said to use the light he would have to go three wire in my mind..After reading that deal from MAD makes me feel all smart and stuff....thanks for all the help guy's.. I have wired a ton of race cars over my life but have never really done the daily driver thing !

[squirrel]

Re: One wire alt replacing a gen..wiring Q'ssss

I use 3 wire alts on cars with idiot lights. I'm an idiot, though

[Eric68]

Re: One wire alt replacing a gen..wiring Q'ssss

It should be real simple, just make sure that the heavy red wire you use for the new alt is a major feed to the fuse box with nothing switching it (like a regulator)

Now if you use a 3 wire alternator you have to install a jumper in the external regulator plug on Chevy's to make it work. I don't think that applies to a one wire deal.

[squirrel]

Re: One wire alt replacing a gen..wiring Q'ssss

Now if you use a 3 wire alternator you have to install a jumper in the external regulator plug on Chevy's to make it work. I don't think that applies to a one wire deal.

that applies to the 62-72 style external regulator cars...it's slightly different on something older that came with a generator

[joe_rocket45]

Re: One wire alt replacing a gen..wiring Q'ssss

no problem, that schematic I posted should cost about $10 (or less) from radio shack for all the parts, they even have cool little plastic black boxes smaller than a pack of cigs it will fit in nicely. I think you could probably use a 324 fro the IC, pin #2 would go to the light and the other side of the light goes to a hot with key on (just remove that LED, it's resistor and the buzzer). R1 should be 1.2K ohm.
The R2 POT will adjust when it kicks on, the zener diode limits current like a regulator incase the alternator spikes or other interference in the system...

of course next time use a three wire and use the jumper wire for the Batt post to the field and the other wire to the light ;)

[Scott Liggett]

Re: One wire alt replacing a gen..wiring Q'ssss

I replaced the generator on the '58 Cadillac with an alternator. I'll have to go out and look what I did to keep the light from coming on. I believe I just left it unhooked.

[SuperBuickGuy]

Re: One wire alt replacing a gen..wiring Q'ssss

Just a question (or two), does the light stay on all the time? does it flicker?
One wire alternators don't generate enough voltage until the field is created - which requires ~1800 rpms to get the electrical field going....