Ok... first things first i have a fairly new optima red top and have replaced my alternator recently in my 71. But here is the whole story.

Quite a while back i had a "buddy" talk me into to taking out my old alternator and removing my external regualtor and going w/a one wire set up (i am calling it this, he was the "brains" behind this before i knew much about charging systems). This is where we removed the external regulator and bought an alternator out of say a 1979 camaro or something like that (this was a long time ago)

Well... it worked fine until my dad and i built my motor and i put 20% underdriven pulleys on the car. Now in idle the car isnt charging. If i have my head lights on and i come to a stop i can see them dim as the idle lopes. Thought i got a bad alternator but after replacing the first one it still does it. And forget if my electric fans are on! Well.... I do like the set up but i dont like the fact that at idle even w/out the headlights on i can see my voltage meter drop to around 12 v and bounce around if the directional is on.

After reading the brand new Chevy High Performance this morning, i am really thinking hard about getting Performance Distributors Mr. Amp alternator (the 130amp). Their set up seems great, you hook it to the battery w/the included thermal circuit breaker, then just hook wires up to the circuit breaker and then a switched 12 v source.

No radical stereo in my car, just elec. fans a heater and lights. Would this be the be solution for me? Thanks for the help guys, i always appreciate it!!

~Paul

I know this may be a dumb question but why did you install underdriven pulleys? Do you race this car; if not your not gaining that much by going with them. With alternators regardless if its stock or 140 amp if your not spinning the alt fast enough it's not going to charge correctly and in some instances it's bad for the alt/battery. I would change out the pulley's and go back to the ones you had on your car before the rebuild; why spend extra money on something that's not needed unless you are looking for every drop of HP? just my .02.

One wire alternators with electric fans are asking for trouble. You need an alternator witha remote sense (meaning the 3 wire set up)>

Ron

I see 2 probs-both already mentioned
1-under drive pulleys :noway:
2- this is debatable but I don't like one wire alternators especially with big current items-your Buddy almost did you a favor until he suggested the one wire version-A three wire int reg alternator is GREAT

What type of alternator is the 3 wire with an internal regulator?? How do i hook it up?? I found the web site my "buddy" got the instructions from, we did the 10SI conversion. (http://www.oldengine.org/unfaq/10si.htm) similar to this page i think. Mine has a 12 volt lug on the back, then the 2 prong plug one wire to "sense" and the other to "excite". Honestly i can only say i have a problem and i really notice it at idle that is it. Thanks for the input guys, if someone can point me in the direction of the 3 wire int regulated one I'd be content if that is what i need. Thanks again.

here are 2 links to the ones i found on line that sound like a good buy (not saying i would buy THESE ones but one like them)

-this is just the regular one (not sure how its regualted)
http://www.performancedistributors.com/alternators-mramp.htm

-this is their "one wire" alternator
http://www.performancedistributors.com/alternators-gm.htm

Find MAD Electrical. They have the right diagrams and even a kit to get it all correct.

Ron

Ron i just read all of the pages in the MAD electrical link (i knew i had heard about it before so i went looking). The more i think about it the more i think we were on the right track. B/c we hooked into the wires that were on the old ext voltage regulator. put a 2 prong plug on them and plugged it in. Then used the existing red wire to hook to the lug on the back of the alt. There isnt just1 wire there, its the heavy guage (12 prob) red wire and then the ones we hooked too and put the 2 prong plug on. Sound right?? B/c my idiot light still works and everything.

AND..... if anyone knows "what type" of alternator this is, can they let me know (like i said think its from a later (like 79 camaro or something of the sort). I would like to order a higher output one but not sure what style i will need. Thanks

Like I stated before if you go back to the larger pulleys your problem might go away; why not do something thats free first and then go from there? Just wondering....

I use a mid 80's Caddy alt
the one wire is the lesser of two evils-can the under drive pulleys-Even a three wire will have probs with under drive pulleys

I have tried swapping pulleys with no avail. I am just not happy with the output of the stock alternator at idle. i appreciate your concern but i really think for what i have i need a higher output at idle.

Can anyone tell me what kind of alternator i have int reg. w/ 3 wires. 10 si??? sound right?? I believe that was the conversion we did was called 10 si conversion and it has 3 wires going into it! Thanks

Thanks for all the help guys!!

I have a one wire Power Master 67294 140 amp alternator in my Camino running electric fans, MSD6la box, cd-ipod changer, and Dakota Digital gauge package. I've had no problems with charging at idle but I'm also running a redtop altma 34b with all new wiring, and March pulley's. It could be your battery that's causing the problem; what type of battery do you have in your car? Remember the more draw you have the more reserve you need in the battery to make up the difference. Do you have a good battery you could try?

I have an optima red top i thought i stated that before, thats my fault. I have electric guages, a DUI distributor, and cd player. I have already had the battery replaced once then i had this one tested. So you have a true "1 wire" alternator?? just a wire from the battery to the alternator? Hopefully my battery isnt the problem (dont see how it could be).

Also can anyone tell me if they think this alternator is probably a 10 or 12 SI?? If so does that matter. I know its an internally regulated delco model just not sure what kind. Thanks.

~P.S. I know it would help if i could look at the alternator but my car is at my parents house and i havent had time to get there to look. Thanks again

If you have the idiot light working then you are not using a single wire regulator. The 10 si alternators went to about 65 amps max as I remember (in a Caddy, not a Chevy) so you can switch to a 12si at 105 amps or a CS130 at up to 300A in after market form. I use a 12si at 105 amps with a number 8 wire from the alternator post (it's output) to the horn relay.

The under drive pulleys can cause a problem if the engine never reaches any rpm (like you were driving in stop and go traffic for a couple of hours and the electric fan kept coming on) but in normal usage (getting above 1800 rpm for more than 10 to 15 min) the alternator should put out enough power (current) to keep your battery charged.

You may have a bad fusible link going to the battery too. It is not open but too high a resistance to allow the battery to charge properly.

If you trace back from the fusible link you may find a bad connection at the terminal post behind the battery or at the horn relay. You can tell by using a voltmeter (DVM). The voltage at the horn relay should be 13.8 to 14.4V with the car running at idle. If it is not then the sense line or the idiot light line has a problem.

If it is 14 volts at the horn relay then go the the battery terminals and measure the voltage on the battery posts, it too should be 14V. If not the path from the horn relay to the battery has a problem.

If it is 14V then your battery is bad (not taking a charge).

Ron

The only reason that I am aware of to use undersized pulleys is to gain rear wheel horsepower by diverting it from charging the battery to driving the rear wheels. If your car is street/strip or mostly street I would suggest stock sized pulleys and a switch mounted on the dash someplace that allows you to turn off the field current to the alternator while racing.

Obviously you need to remember to turn it back on when you are not racing but your alternator light will remind you to do that.

Turning off the field current completely removes the parasitic power loss while charging the battery during the race. I imagine you might even gain one or two horsepower for your quarter mile journey.

With a fully charged battery there will be no downside to not charging your battery for that short trip.

Thanks for all of the help guys. I really appreciate it. Im gonna head to the parents house and tinker with the car for a while friday night and see if i cant try all the stuff you guys suggested before i go any further. What is the best way to test my fusible link from the horn relay back (not to the battery to the fuse block) if i know that my car is not putting out 13.8-14.4 volts at idle?!?!?!? Thanks again!! It's always a pleasure knowing i can count on you guys for help when i need it. Hopefully I can figure this out.

~Paul

Thanks for all of the help guys. I really appreciate it. Im gonna head to the parents house and tinker with the car for a while friday night and see if i cant try all the stuff you guys suggested before i go any further. What is the best way to test my fusible link from the horn relay back (not to the battery to the fuse block) if i know that my car is not putting out 13.8-14.4 volts at idle?!?!?!? Thanks again!! It's always a pleasure knowing i can count on you guys for help when i need it. Hopefully I can figure this out.

~Paul

Simple check of the fusible link: with the car running and the battery fully charged put a voltmeter across the fusible link (usually from the battery terminal to the post). If the voltage is more than 0.25V or so the link is questionable.

If it is bad, then something caused an over current condition to make it become defective or it got corroded from battery acid leakage. If it was an over current condition you may have a problem some where else.

Ron

So you have a true "1 wire" alternator?? just a wire from the battery to the alternator?
Correct. I've installed a Painless kit in my '67 Camino; its Part #10102 Universal Streetrod Harness (12 Circuit/Non-GM column). Because I'm running a 140 amp alt I had you use and extra Red 10 gauge wire and the 8 Gauge wire but they run off the same terminal. There are instruction in the manaul you can download with detailed pictures on page 7. The manaul is at: http://www.painlesswiring.com/Manuals/10102.pdf

From the Painless manual:

GM One-Wire Alternator.
7.2.4 Connect ENGINE SECTION wire #915 (red) to the Alternator Output lug (Bat). Insulate and stow ENGINE SECTION wire #914 (wht). Do not install jumper wire. No wires are connected to Alternator terminals 1 & 2. If alternator output is greater than 65 amps refer to Figure 7-2B and the caution on page 6. 7.2.5 When using a 1-wire alternator you must use a voltmeter or ammeter. A WARNING LIGHT CANNOT BE WIRED IN.
CAUTION: IF USING AN ALTERNATOR WITH AN OUTPUT LARGER THAN 65 AMPS, YOU WILL ALSO NEED TO USE THE RED 10 GAUGE WIRE #960 AND THE RED 8 GAUGE WIRE INCLUDED IN THE BOX. THE WIRE END WITH THE RING TERMINAL AND RUBBER BOOT WILL CONNECT TO THE ALTERNATOR OUTPUT LUG WITH #915. ROUTE THE OTHER END TO THE MAXI FUSE TERMINAL WITH WIRE #916. CUT THE WIRE AND CRIMP ON A RING TERMINAL. NOW INSTALL A RING TERMINAL ON THE REMAINING RED 8 GAUGE WIRE AND ATTACH IT TO THE STARTER SIDE TERMINAL OF THE MAXI FUSE. CUT THE 8 GAUGE RED WIRE TO LENGTH, CRIMP ON A RING TERMINAL AND ATTACH IT TO THE MAIN SOLENOID LUG WITH THE POSITIVE BATTERY CABLE. SEE FIGURE 7-2B.

Alright... Thanks for all the info guys!! I really do appreciate it. Hope all goes well.

~Paul

with an underdrive pulley the car WILL NOT CHARGE at idle because you are not spinning the alternator fast enough. i know this cuz i had an S-10 and have a 93 Z28 with underdrive pulleys. both charged fine at idle before install of the pulleys, after installing the pulleys neither charged at idle. just figured i would chime in and save you all the thinking about it. you might have to ditch the pulleys to run your fans and whatever else you are running. i know they are pretty but they can also be a pain in the a$$

I found out the perils of underdrive pulleys by accident. When I put the ProCharger on I used the spaced out alternator pulley they give you. I didn't even notice that it was 3.5" diameter vs. 2.2" on the stock one until my car would not start in the staging lanes. I put the stock pulley back on and wallah, battery charged. You really need to lose the underdrive pulleys.

If you put the stock pulleys back on and it still doesn't work then you know something is going bad. Could be the alternator, battery, wires.

Have you added any electrical accessories since the time it "used to work"? If so, are you using relays and pulling the power from the buss bar? If you are running the hot wire to the battery or the fuse box then there is another major issue you need to address.

You found the Madd electrical site. Keep reading. Go to the tech articles section and read 'em all. Everything you need to know is on that site including how to identify which alternator you have and what cars the 10 and 12SIs came on.

Thanks for all of the help guys. Everything else checked out. Out go the under drive pulleys i guess. Can anyone tell me where to get some "stock" pulleys that look good (that are not chrome)?? I like the look of the aluminum under drive pulleys i have. Thanks again guys!

~Paul

Hey guys wanted to let ya know i got the prob. figured out. Re-did some wiring (just to make a few better connections. Then got rid of the under drive pulleys. Works a lot better (never drops below 12 volts at idle).

Could someone maybe tell me (im pretty sure i have an idea) why when everything is on (e-fans, heater blower motor, radio and turn signal) i dont drop below 13.5 volts but then i turn on my head lights and i drop right down around 12.5 or so. Im assuming that it's because it turns on head lights, marker lights, tail lights and side markers, along with the dash lights. Is that a fair assumption, i didnt get a chance to drive it; i let it warm up in the driveway and tried reving it and the volts climb up when i do that. So im just assuming it might be because i had just about every electrical component on when its idling w/the lights on. Thanks for all of the help guys!!! Greatly appreciated!

~Paul

Hey guys wanted to let ya know i got the prob. figured out. Re-did some wiring (just to make a few better connections. Then got rid of the under drive pulleys. Works a lot better (never drops below 12 volts at idle).

Could someone maybe tell me (im pretty sure i have an idea) why when everything is on (e-fans, heater blower motor, radio and turn signal) i dont drop below 13.5 volts but then i turn on my head lights and i drop right down around 12.5 or so. Im assuming that it's because it turns on head lights, marker lights, tail lights and side markers, along with the dash lights. Is that a fair assumption, i didnt get a chance to drive it; i let it warm up in the driveway and tried reving it and the volts climb up when i do that. So im just assuming it might be because i had just about every electrical component on when its idling w/the lights on. Thanks for all of the help guys!!! Greatly appreciated!

~Paul

I assume you are measuring at the voltage at the point of regulation (usually the horn relay) but if you rewired it that might not be the case.

12.5V is too low, the alternator does not have enough output at low rpm; meaning that during this time you are draining the battery.That is why when you turn on the lights the voltage drops; you are at the limit of the alternators ability to put out current at that rpm.

The chances of this being a normal operating condition (everything is on is a very rare event) are small however. You would have to sit at idle with everything on for hours to actually drain the battery.

You also state that if you rev it up the voltage climbs. What does it climb to? If it is above 13.8V at 1200 rpm you are fine.

Ron

Ya ron that was what i was trying to convey (i need to do a better job of explaining myself). It will sit anywhere between 13.8 and a little over 14 at idle w/nothing on. In gear with everything on it will be aroudnd 12.5 or so (which would be all i mentioned being turned on sitting at say a stop light). But when i rev it up in park (with everything on) it will climb right around the 13.8 mark. I am pretty happy with it. I was just trying to give myself a little piece of mind about why it drops voltage so much when i turn the head lights on (its fine with everything else on, only drops say .5 volts at idle, but drops significantly when i turn the head lights on). I will have to take it out and drive it for a while to let ya know the complete run down. But my only slight concern was why the voltage drops so significantly when i turn the lights on?? Thanks

~Paul

Ya ron that was what i was trying to convey (i need to do a better job of explaining myself). It will sit anywhere between 13.8 and a little over 14 at idle w/nothing on. In gear with everything on it will be aroudnd 12.5 or so (which would be all i mentioned being turned on sitting at say a stop light). But when i rev it up in park (with everything on) it will climb right around the 13.8 mark. I am pretty happy with it. I was just trying to give myself a little piece of mind about why it drops voltage so much when i turn the head lights on (its fine with everything else on, only drops say .5 volts at idle, but drops significantly when i turn the head lights on). I will have to take it out and drive it for a while to let ya know the complete run down. But my only slight concern was why the voltage drops so significantly when i turn the lights on?? Thanks

~Paul

Paul, to be clear:
When you turn the lights on at idle the alternator can't keep up, it is still putting out current but the alternators output voltage has dropped and now the battery is making up what the alternator can't do.

With everything else on the lights are pushing it over the edge. Nothing wrong with this provided you don't sit at a light with everything on for a few hours.

Ron

Thanks again ron. That is what i figured i just wanted to make sure i didnt have to chase any other "problems" down. Thanks a lot!