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Old 04-19-2008, 04:42 PM
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3 wire alternator hookup

I searched all the threads and while all are helpful. I still have a few questions before I hookup the 3 wire Powermaster 100 Amp Alt on my '62 Corvette.

Basically this is what I understand. From the main Bat connector on the alternator I am going to use an 8 gauge wire to a junction box. From the junction box I run a fused link and 10 gauge wire to the starter battery terminal. The red wire from the plug on the alternator goes to the junction box. From the junction box I then run a 12 gauge power-up wire with a fusible link to the ign switch. The other wire from the alternator plug goes an "idiot light" which its other end goes to ?

When I get around to installing relays for the headlight, do I run another 12 gauge red wire to the relays, then procede with the regular headlight wiring from the relays?

Is this all correct ? or do I need to do something different. The car has an HEI dist and I need to get full voltage to it. Currently the one-wire Alt is only delivering about 12 volts (anyone want to buy an almost new chrome Proform 100 amp, 1 wire Alt - cheap !).
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Old 04-19-2008, 05:34 PM
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This might help you
or maybe this one...joe
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Old 04-19-2008, 06:02 PM
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gcd,
here's a link from the "Knowledge Base" link at the top of the page under "electrical"....

100's of excellent articles broken down by car part and/or specific car

http://www.madelectrical.com/electri...evymain1.shtml

I do perfer a 3 wire but did you have the one wire tested for free at a local parts store?....
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Old 04-19-2008, 06:21 PM
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Red - Thanks, I have that info from MAD, but what is not shown in the "new system" diagram are the two plug-in wires. I believe the red #12 goes to the junction box, and the other is for the warning light. My car never had a warning light (shows it's charging) so I need to know where the wire(s) attach too..

p.s. I finally got the carb ironed out and it seems to be responding correctly. I now need to get the full voltage to the HEI as the one wire only gets to about 12 volts to the unit. The one-wire alt is fine, but it can't sense the need for the increased voltage
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Old 04-20-2008, 07:11 AM
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GCD,
(I'm still in a fog for what your asking)

purpose of the regulator "idiot light" wire is to feed power from the batt direct ign switch wire to the external regulator only when the ign switch is turned on to turn on the regulator...

maybe this external regulator (ford) diagram will help...they all work the same

diagram footnote:
"if" the alt isn't putting out enough volts to over power the parallel wired idiot light resistor then the lamp will light indicating no alt charge
....................................
???"check simple first"=the alt belt must be tight enough for NO slippage=make sure you are not up against the belt tightening adjustment limit= a mega amps alt puts alot of drag on the belt

??? a one wire alt turns itself on with just with rpms...
the rpms make a magnetic field strong enough to switch on the internal regulator if the alt is ok so why is yours not working at all = your guage may be dead?...test at the alt with a DVM at 2k to know for sure the alt is dead = if the alt is putting out it may well be voltage drop in the harness to the guage (AND the ign)...wires do wear out and gain resistance

??? most/alot of one wire alt do have a second terminal so you can have voltage sensing instead of rpms (only shows charge while driving) based volts regulation

I'm not comprehending something...I'll ask T-bucket to have a look at this thread
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Old 04-20-2008, 03:01 PM
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I dont understant the question, on a 3 wire Gm 10 or 12 SI style alternator, you need a battery feed to the large stud, this is live all the time, of the 2 small terminals 1 goes to the light ( I think it is terminal 2) and the other goes to a live with key on spot in the harness for voltage sense. If this voltage sense has no voltage the alternator wont work. Some people will just run a jumper from the large stud on the alternator to the sense terminal , this works but is not the best for 2 reasons, 1 you are not getting a true voltage sense reading and 2 it is not switched so effectivly the electronics in the alternator are always on.
You can convert that 1 wire to a 3 wire by changing the regulator.
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Old 04-20-2008, 05:45 PM
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To clarify - The one wire alternator on the car - a '62 Corvette with HEI dist - is working, but it only puts out 12 volts max with the one wire hookup. This is confirmed by checking the output both at the batt term on the alternator and at the connection to the HEI unit. The reason to go to the 3 wire is to get the higher voltage to the HEI (and other parts). I hooked up the 3 wire alternator today with an 8 gauge from alternator to junction, 12 gauge from junction to starter/battery terminal. I ran a 12 gauge wire from the #2 plug on the alternator to the junction. Started the car, the volt meter now reads a consistent 14 volts, and I am getting 14 volts at the terminal to the HEI. I did not connect the other wire from the alternator plug. This wire, as I understand, is for the "idiot light" top indicate if the battery is charging. '62 Corvettes never had the light, but I am looking to hook one up. I need to know what wires are need and where they hookup from the plug in terminal on the alternator. I have an the light, an led indicator light from Jegs and want to know exactly what wires hook to from the alt. terminal plug, to the light and whatever else.
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Old 04-21-2008, 08:54 AM
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GCD,
(I'm scratchin' my head...)

you have a volts guage on the dash right?
that's your "idiot light"....
shows only 12V at 1500+rpms= alt is dead

if you don't have a volts guage in the car...
DO buy one because it can/will indicate many many other electrical gremlins...
(anything/everything from a faulty headlights ground to a blower motor close to dieing to a worn brake lights switch etc etc etc....because the needle will "twitch" and show less volts when any device is operated)
very simple to add a volts guage and 100's of styles and types to choose from to look purdy

???? the only thing you will gain by adding a idiot light... (with a volts guage in the car).... is it will remind/warn you that you left the keys in the ign and the ign on....aka buzzer/bonger alarm on new cars....

contact Powermaster and Jegs for instructions for how to add a idiot light...because the parallel ohms resistor value must be correct for the lamp watts and circuit or it won't work correct
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Old 04-21-2008, 09:23 AM
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GCD,
if I read your last post correct...

you have the sensing wire connected to the "batt direct" junction...(same as T buckets "jumper" wire post above just further away)....

that means there is always power to the regulator even with the key off...

and the alt is sensing and adjusting the batt volts hooked to the junction...not the actual ign volts

voltage sensing needs to be on a "only power" when the ign is on feed from the ign switch....

CAUTION this is a extreme example)
on my car, the sensing wire is connected to the dist ign module power feed wire,...that way the alt is reading/sensing the actual volts at "the end of the line" after going thru all of the old harnesses and connections resistance....
CAUTION BECAUSE you don't want to feed more than 14.5V to the batt from the alt or it can EXPLODE!!!!
which if you do have a major voltage drop in the harness the alt will do!!!!!

money well spent=buy a vette wiring diagrams book....
I'd wire it all original with a SS external regulator and about a 60-70amps alt...you don't need 100 amps unless you have a mega watts radio/electric windows/seats/etc....the stock wiring sizes isn't designed for that many amps

Last edited by red65mustang; 04-21-2008 at 10:13 AM.
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Old 04-21-2008, 08:19 PM
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I agree with Red, if you have 12v at 1500rpm, your alt is dead regardless if it's a one wire or traditional .

Vince
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Old 04-21-2008, 08:29 PM
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hot alternator

hey guys when you jump the field winding blade (1) down to the battery terminal of the alternator you have the field windings always energized. this will produce lots of heat this should be wired to switched ignition! it will also result in a dead battery if the car sits long enough. look on a factory set up it is never jumped directly to the battery.

this way when the car is off the field windings are not energized! blade to can run an amp meter also i am told.
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