I think my alternator is dead?

[Larry Callahan]

I forgot my volt meter at work so I did a data log and noticed an odd trend. As the RPM goes up the voltage goes down. In a couple of days I will have my meter back and can check it then but, I'm pretty sure the voltage shouldn't drop to 10 volts at 6,000 rpm.

43078

[rrunner68]

Yeah, I'd trade that rattle trap in for a Mopar. As a matter of fact, I think you mentioned something about test driving a Road Runner, lol.

[JRouche]

I think its belt slip. The dives in voltage then the rise looks like a belt slipping for a small time period then gripping (voltage rise). I dont think its an electrical issue, it would be uniform in drop or rise. I actually havent seen electrical components act like that. Mechanical components YES.. Id check the tension of the belt. Is it an old style belt or a newer style belt with a belt tensioner. If newer Id check the tensioner to make sure the bearings on it are not fried.

If its an old style I would check the tension and the age of the belt. Rubber will get hard and slippy. And as time goes on and it slips more it will make for some grippy (yeah, thats a technical word LOL) sections, where it has slipped and cleaned off the hard outer surface. The cleaned surface will grip more. A simple test, but not a cure would be to use some belt dressing. I dont like to use it, I would rather use a new belt or a different kind of belt, there are differences in belts. But for a quick check to see if a belt is slipping its a simple check.

If yer belt is more than five years old and from an unknown source I would replace it. And when doing so check the pulleys and make sure they are clean and there isnt any issues with them. JR

Oh, its hard to see what the time period is for the drop in voltage. If its minutes then delete my response hahaha, a belt doesn't slide that long then grip. But if its in milliseconds or faster then I think belt. I couldnt see the time table.

Oh, and if it is in milliseconds you might think heck, that shouldnt drop my overall voltage down that much. But I think it can. You have to average it out over time. There are just as many drops (maybe a lil less) as there are peak voltage periods.

Oh, one other thing I was thinking about. Electronics dont care about speed, mechanical systems do. You seem to be dropping voltage at a higher RPM. 6000 RPM is slow for electrical systems. Mechanical systems will be affected with speed, electrical systems not so much, 6000 rpm is at a stand still for the electrical side of the whole deal.

[Larry Callahan]

Maybe I will warm it up tomorrow then remove the belt and run it for a couple of minutes and see what the voltage is like.

[CarlC]

Larry,

You may just want to remove the alternator and have it tested at NAPA or Pep Boys to be sure. An hour or two of work may be a good insurance policy.

[Vegas69]

Battery voltage shouldn't be affected that quickly. Even if the alternator quit working, system voltage should be 12.6 or so. I have to wonder if your program is accurate. The REAL QUESTION, did it cause any drivability problems? Why are you looking inot system voltage?

[MonzaRacer]

Another thought is that at higher rpms the brushes are bouncing due to the slip rings not being concentric AND weak springs or worn down brushes.
It can also cause odd reactions in electronics too, so a proper diagnosis is called for. Also dont forget to double check on AC with your meter if your getting more than 60 milliamps AC current at the battery terminals when you add a load to the system like flipping the on the high beams on and off. on older alternators and good battery you can live with it in the 60mA range, new alternators should be in the 0 to 40mA range.
As little as 100mA can cause electronics to foul up. I can even live with 80mA on older age alternators but eventually the battery wont take it and the diodes do not get better.

[SLO_Z28]

Absolutely check for AC voltage as stated, as little as 20ma can cause the computer to fail. Either that data logger is WAY off or your battery is completely dead. I doubt its that bad. What computer are you using, if its GM I have a ton of experience on it and could look at it.

What kind of alternator are you using, is it a CS144? CS130? What is your belt setup?

[Larry Callahan]

I will run it over to Pep Boys today and see if they can check it.

Below is a picture of it and the Power Master tag. It's mounted in a Vintage Air front runner system.

https://www.pro-touring.com/vintageair/144-4474_IMG.jpg

[CarlC]

You could bolt up a nice LS7 and cure that problem pronto.

[SLO_Z28]

Hard to tell from the pic but does the back look like:
https://static1.pt-content.com/images/pt/2010/12/71347861_2-1.jpg\
If it is then Pep Boys will need an application for a part number. 7901601 should work, thats from memory though, and ive been out of the parts business for some time now.

[Larry Callahan]

Can't tell what the back looks like. It's a one wire deal.

[kryptik]

Why are you running a one-wire Alternator?

[MonzaRacer]

CSI alternators are not one wire as far as I know. As for the system specs 40mA is max testing spec on new alternators. Unless your battery is a complete POS 20mA will never effect the car.
Again anything at or under 40mA is ok, steady AC output is not eve if under 40mA, its indicative of a weak diode.
And I can tell you the Midtronics setup at Pep Boys may not catch a weak diode, I like using the multimeter feature, and then flip the high beams on and off. you will see if the diodes clamp good or not.
Remember 40mA or less on new alts
60mA max on older units with miles and if it spikes over that the bare minimum and still be able to drive without damage would be 80mA. If it spikes over that or has steady ac voltage output its got bad diodes.

[SLO_Z28]

Unless your battery is a complete POS 20mA will never effect the car.

Tell that to the Dodge and Chevy trucks that have major issues with 25ma of AC. The dodge flat out wouldn't shift right with that voltage. To be fair that truck has to power 150 amps of police equipment with the stock battery and alternator.

Also dump that 1 wire alternator and get something worth having. That car is too nice for a one wire.

[Larry Callahan]

I never knew there was an issue with a one wire. That's what came with the system so I used it. I had always thought that was the hot ticket. Earlier today I read up a bit and it looks like a lot of people don't care for them.

It also looks like my alternator might work wired either way? Power Master talks about a plastic cover I could remove and wire it differently. I will call them on Monday to talk about it.

[JRouche]

I never knew there was an issue with a one wire. That's what came with the system so I used it. I had always thought that was the hot ticket. Earlier today I read up a bit and it looks like a lot of people don't care for them.



Hmm, Im in the same boat, I thought the one wire alt was the ticket. Are folks having issues with them. I have an inexpensive powermaster one wire 100amp alt and dont have any probs. What are some of the probs you have read about? Maybe something I should look out for, so far so good, but you never know. JR

[Larry Callahan]

Hmm, Im in the same boat, I thought the one wire alt was the ticket. Are folks having issues with them. I have an inexpensive powermaster one wire 100amp alt and dont have any probs. What are some of the probs you have read about? Maybe something I should look out for, so far so good, but you never know. JR

I'm now sold on a 3 wire. After reading this article http://www.madelectrical.com/electricaltech/onewire-threewire.shtml I will look into changing it out after the holidays.

[kryptik]

The three-wire's most beneficial feature is remote voltage sensing. Remote voltage sensing allows the alternator to "know" the amount of voltage at a particular point in the electrical system; this can be anywhere, but usually the main junction/fuseblock under the dash. Contrarily, a one-wire only senses the voltage from it's charging post. Let me give you an example:

Say the one-wire alternator is happily producing 14.4V at the back post. This is great until you factor in the amount of voltage drop through your electrical system (especially if there are many crimped connections). By the time you read voltage at the fuse block it can be much lower (hypothetically 12.6V). A three-wire alternator employs a positive wire which comes from the fuseblock; the voltage regulator will increase voltage until THAT wire is showing ~14 volts...not the back of the alternator (which now may be ~16 volts).

Sensitive automotive electronics work best when fed the voltage they were designed for...~14 volts.

[Larry Callahan]

The three-wire's most beneficial feature is remote voltage sensing. Remote voltage sensing allows the alternator to "know" the amount of voltage at a particular point in the electrical system; this can be anywhere, but usually the main junction/fuseblock under the dash. Contrarily, a one-wire only senses the voltage from it's charging post. Let me give you an example:

Say the one-wire alternator is happily producing 14.4V at the back post. This is great until you factor in the amount of voltage drop through your electrical system (especially if there are many crimped connections). By the time you read voltage at the fuse block it can be much lower (hypothetically 12.6V). A three-wire alternator employs a positive wire which comes from the fuseblock; the voltage regulator will increase voltage until THAT wire is showing ~14 volts...not the back of the alternator (which now may be ~16 volts).

Sensitive automotive electronics work best when fed the voltage they were designed for...~14 volts.


And with lots of junk drawing power and my batteries in the trunk I think a three wire is the way to go.

[Larry Callahan]

O.k.. This is embarrassing. I have determined that I do in fact have a three wire model. I for some dumb reason wired it as a one wire. I wired a lot of the car before I sent it to Prodigy Customs and that was one of the items I wired.

I'm such an idiot. I hacked up the wire harness and removed the extra wires to run a one wire that I never had. Where I got the info or why I thought I had a one wire is beyond me.:hand:

[PhillipM]

Doh!

[Larry Callahan]

Well, it now gets more confusing.

The Power Master http://www.summitracing.com/parts/PWM-47861/ is not actually a three wire. They say all I need is the large main wire to the starter post and a single switched energizing wire.

So what? It's a two wire with an internal voltage sensing? Sounds a lot like a one wire with with an on switch.

[kryptik]

That's strange...

Give National Quickstart a call (or check out their site HERE (http://www.alternatorparts.com/category_cs144.html)). They'll hook you up with a quality OEM 3-wire CS144 and 12Si->CS adapter harness for a good price. They'll even install any type of pulley before shipment for no extra charge.

Everyone makes mistakes...that's what this forum is for :)

Cheers,
Matt

[CarlC]

How in the heck did it run for so long without killing the battery?

[Larry Callahan]

How in the heck did it run for so long without killing the battery?

I'm not sure. I have a feeling that it does self energize some times. I fired it up 4 times in the last two days and one of the three times it idled at 14 volts. All the other times in the low 12's.

Not knowing when I will drive it next I have always hooked up a battery tender so I don't have to worry about it. Powermaster says it won't work without the switched energizer wire hooked up but I can't believe that my dual Optima yellow tops work that well. I ran everything including two large radiator fans in 100+ degree weather round trip to the Peterson Museum. That's 40 miles each way and the trip home took over 90 minutes in stop and go traffic on a day when it was over 100 degrees.

[Vegas69]

Vintage air has your answer. I've found my 1 wire alternator to only charge when needed.

[Larry Callahan]

I called Vintage Air.

o.k.. This gets even more confusing.

Vintage Air says it is a one wire alternator. Don't hook anything other wires up. Power Master says I need to hook up an energizing wire as it is not a one wire alternator.

My head is going to explode.

Vintage Air thinks I should try a ground wire from the alternator case/bolt to the chassis. There is a small chance that the anodized brackets I am running might be electrically insulating it.

In the end, I like the idea of the external voltage sensing function of a three wire and will probably order one despite Powermaster strongly recommending against that.

[Vegas69]

With fuel injection, I agree that it needs 13.5-14.5 volts all the time. Injector pulse and the correct fuel pressure is just to crucial. With a one wire, it's either 12.8v or 14 when it's charging. I'd go 3 wire if I had it to do all over again. Luckily I have a carb.

[kryptik]

Why would Powermaster recommend AGAINST a three-wire? Never heard of that one before... somethin' sounds a bit fishy.

And it's not only fuel injection that benefits...digital ignitions, digital fan controllers, gauges, etc should all have steady, proper voltage.

[James OLC]

I called Vintage Air.

o.k.. This gets even more confusing.

Vintage Air says it is a one wire alternator. Don't hook anything other wires up. Power Master says I need to hook up an energizing wire as it is not a one wire alternator.

My head is going to explode.

Vintage Air thinks I should try a ground wire from the alternator case/bolt to the chassis. There is a small chance that the anodized brackets I am running might be electrically insulating it.

In the end, I like the idea of the external voltage sensing function of a three wire and will probably order one despite Powermaster strongly recommending against that.

Been there, done that, solved the problem...

When we first ran the OLC in the standing mile at Silver State the car would run fine then abruptly shut off at WOT (at 140 and change). We chased alternator issues 14 ways from Sunday and finally the old dude at David's alternator shop brought up the ground/anodizing issue. It seems strange that it's not a constant but that was our (first) alternator problem and solution. Good luck Larry

[SLO_Z28]

Been there, done that, solved the problem...

When we first ran the OLC in the standing mile at Silver State the car would run fine then abruptly shut off at WOT (at 140 and change). We chased alternator issues 14 ways from Sunday and finally the old dude at David's alternator shop brought up the ground/anodizing issue. It seems strange that it's not a constant but that was our (first) alternator problem and solution. Good luck Larry

The ground may pass smaller current levels fine but pig out at higher current levels, this scenario makes perfect sense to me and I experience it from time to time(even this morning lol). I don't like seeing anything over 1 ohm in the ground circuit for computers or radios. Also with the system running put your volt meter on the B+ (big output wire) and on the battery positive cable, set it to DCV and check the voltage, anything over .3 is REALLY bad, I don't like seeing anything over .150, this checks how much your voltage drops.

A 3 wire will regulate your voltage very well. Don't be afraid to add extra ground points either, on police cars there are 30+ extra grounds. I like to use the factory ground strap bolt hole on the back of a gen1 sbc to run a 10 gauge wire to the trunk at the point of your chassis ground, I don't know offhand where that is on a lsx but I'm sure there's room somewhere. Id run at least a very high quality 8 gauge wire all the way to the positive in the trunk. Make sure and scrape any paint or coatings off the ground, where the alternator grounds, and where the starter mounts. It sounds silly but Ive seen quite a few times where someone painted the alternator or starter and couldn't figure out why it wasn't working.

[David Pozzi]

Make sure you rev the engine above 2000 rpms before testing for alternator output if you have it wired as a one wire alternator. Also run a ground wire to the cyl head or block.
David

[The WidowMaker]

i called powermaster to check to see if my 1 wire can be converted to 3 wire. some of them have a plug on the side that can be removed and the other 2 wires connected. mine cannot be converted without sending it back to them and having them change the regulator. ship it to them, pay $30 and its done.

he did say that newer alternators do not need to be 3 wire. he said they have come a long way in even the last 5 years. when i told him my plans of fans, a/c, efi etc. he still didnt change his opinion. he also said that a 3 wire can sometimes over-energize a faulty circuit (bad connections lead to voltage drop and alt runs really high volt to make up for it when proper wiring would have solved it).

i may just pay the $30 and not have to worry.

[Larry Callahan]

o.k.. I am re-wiring MotiV8r for a 3 wire. I have found several ways to wire it. I tried all week to order the kit and manual from MAD. I called 20-30 times and I got either a busy signal or no answer. So, I give up on them and now I am trying to figure out how to wire it myself.

So, I figured out what connector I need and picked it up at NAPA. Now, I see a few different ways to wire it up and it's driving me crazy. Most people I find say to hook the "S" wire right to the output of the alternator. Is that the sensing wire? It seems to me it would be better to hook it to a junction under the dash to sens the wire that everything is running off of.

Now, one of the wires I understand is an exciter wire that should be switched. Should it have a resistor wired inline? And is that "L"

Are "F" an "P" not used at all?

Where would a diode go?

Man I wish MAD would answer the phone.

[BonzoHansen]

In my car I ran the sensing wire along with the BAT lead to a junction point, and the L lead I spliced to the factory L lead. That is the lead that needs a resistor in most cases. GM says to jump the S lead to the BAT term in their serp kits. I dug up an old post.


I tripped on this the other day. This is a screen cap from a larger install document I found on the GMPP site. It is how GM Performance Parts says to wire the CS130 that comes with the serp setup they sell. IROC setup. They just jump the S term to the BAT stud. I ran that lead along with the BAT lead to a junction point. I ran the factory brown idiot light circuit to the L term.

https://static1.pt-content.com/images/pt/2010/02/th_CS130_Wiring_As_Per_GMPP-1.png (http://smg.photobucket.com/albums/v359/SIBLY/Cars/?action=view&current=CS130_Wiring_As_Per_GMPP.png)

[Larry Callahan]

Thanks! Now that makes sense. I will just run the sensing wire under the dash and grab a 50ohm resistor. Now, does it matter what direction the resistor is wired in?

[BonzoHansen]

I don't think so, not like a diode would matter. If you do it like GM recommends, I see no reason to leave the engine compartment. There has to be a start&run hot under the hood to run the brown wire to, with the resistor in place. JP will tell us if I'm wrong.

[Larry Callahan]

Thanks

[Larry Callahan]

Well, I sent my alternator to Power Master and had them replace the regulator and set it up for a 3 wire.

They shipped it ans it should arrive on Friday. I will have it wired up and ready to drop it in by then.