Here we go, I must fix this charging problem. Everythings fine till I try to idle for a while with a full load on.

With just engine running the battery volage is 14.xx, pretty good. When bad weather hits and I am running lights, wipers, A/C and stereo it will drop slowly down to 11.xx volts while idling, driving it will climb up to 13.xx loaded. I am also using a digital multimeter, not the gauge. I took reading at the alternator and battery to make sure it wasn't a voltage drop problem.

This low voltage makes the car run poorly so I am determined to fix it. The alternator is a new 105 amp from Autozone. Battery is at least 4 years old from Wal-mart. Any ideas where to start?
BTW, the alt. gets too hot to touch after 5 mins. fully loaded.


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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project

 

heres how you tell...
take a reading of the batt with car OFF, it should be around 12.00
then turn the lights, blower, and radio on, if it drops below 10.00 or very close to that then it is the batt

 

Your alternator will build up a ton of heat loaded. Ever wonder why they tell you not to recharge a dead battery with a new alternator? Thats because 90% of the alternators out there would overheat and blow out before charging the battery back. The rated capacity is more of a peak value than a continuous sustained output.

The voltage levels you are seeing sound pretty normal to be honest. The stock alternators don't output as much power as you can draw at idle speeds. This is one reason GM redesigned the alternator in '87. The newer style has a better low speed output, but also overheats much easier (sigh). What I am concerned with is why you think this is making your car run poorly. The car should run fine all day long in the 11V range. If I were to make a guess whats happening is you are drawing quite a bit of horsepower off the crank at idle. It is normal to kick the idle speed up when the A/C is on to compensate for the load. The built up engine is probably lugging a little at idle. That will make it shake and run poorly until you give it a little gas. Then the alternator spins a little faster and the voltage boosts up, but its rather unrelated.

[This message has been edited by Grand Prix (edited July 05, 2001).]

 

I am saying the car runs poorly due to low voltage. Everything runs slower and little things just arn't right. The system is on;y getting 11 volts at the battery, with voltage losses throughout the wire harness some stuff is probally below 10 volts. Fuel pump(external high perf) runs slower, duel fans run slower, lights are dim, computer and most importantly the ignition is not performing at peak. Temps start rising due to lower fan speeds, heat builds up, voltage drops more due to hot alternator, voltage drops more, ect...


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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project

 

EDIT because your above post was simultaneous with mine:

The voltages you gave (and thank you for using a DMM, or Digital Voltmeter!) under the conditions you described are more or less normal. A little on the low side, but I think still okay - sorta-kinda.

Perhaps the alternator has lost output capacity. This could be because a diode went bad causing you to lose one of the three phases, or ~33%. The alternator will still work "normally", but just weaker. The answer would be to test it (especially the output capacity). You could do this yourself if you know how to test diodes (there are six), which is what the rectifier is. The test is easy to do. The rectifier is the part that often goes bad when these alternators overheat (mine did).

You sound like me. Things have to be just right (how do you spell "perfectionist"?). If I were you, the way I'd solve this problem (inconvience?) would be to get a larger (both physically and electrically) alternator to get more output and eliminate the darn overheating problem of CS130 alternators. See the above post for a good suggestion. Also, do a search (use my name) for a post made about getting an aftermarket alternator that should give you some good suggestions. I think it was made in the "engine" section about a month ago. Search for CS-144 or CS144 in the text.

[This message has been edited by Stuart Moss (edited July 05, 2001).]

 

Stewart,
I was thinking of the "IceBurg" 140 amp rebuild. Any comments there? Here's the websight. http://www.alternatorparts.com/7130_7140%20.htm

Also, I'm unsure of the battery condition. Could it be related? For example, if I were to leave the lights on for an hour, the car would not start, not even turn over. Click, click, click. Ask me how I know!



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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project

 

What is your idle RPM while all of this is happening?

 

Idle RPM is 650. Volts do increase if I rev it up some, say 1500 RPM.

 

John, I just had to replace BOTH my alternator and battery. There was no doubt that my alternator went bad (no voltage above 12 volts at any rpm). So I replaced it but I found that I still was getting low voltage at idle. (Yes, I do have underdrive pullies, but this was lower than normal). A good high amperage battery has helped that and now I have plenty of voltage everywhere...even more at idle than I normally get with the underdrive pullies.

PS: There is a "correction" table for the Voltage/Injector Pulse width. It does adjust for lower voltage, but I felt that the table could use some tweaking as I too noticed a drop in performance/idle quality with the drop in voltage.

 

John,

Yes, that site was discussed here a few weeks ago. Look at https://www.thirdgen.org/messgboard/...ML/009974.html for a discussion that you will probably find interesting.

Regarding the battery being the problem. Well, I wouldn't be looking there for the problem since the alternator is doing all the work once the alternator is running, so as long as you see more than battery voltage (~12.6 volts) with the alternator running, you can presume that the alternator is supplying all the electrical needs. But once the voltage drops below battery voltage (~12.6 volts), then you can presume that the battery is supplying at least part of the current needs.

That said, I'd suggest you have the battery checked (by doing a load test), which many places will do for free. More importantly, I'd want to know what the alternator voltage/current output is (continuously if possible). You should be able to determine this free from any number of popular auto parts stores.

If a system voltage under ~13.0 volts is unacceptable for you at any time (e.g. idle), then I think you'd be a good candidate for a larger capacity (and preferably larger case) alternator. Most people don't care about this temporary voltage drop during idle, which is considered "normal", but I certainly understand (and agree) with what you are saying. But less than ~13 volts while at speed is another thing and would be (IMO) good cause to upgrade the alternator.

Again, take a look at the link I put in this post and let me know what you think. I'm waiting for Jason to report back to see how it worked for him before I make a purchase. I'd sure like to get that modified large case CS144 (From "Premier Power Welder" as linked in the referenced post), but at ~$700, I've placed it on "my list" of things to get.

EDIT:
Regarding your statement about loading the battery with the lights on for an hour and then not being able to crank the engine. If it were me, I'd be thinking about getting a new battery soon, but nothing urgent. But I doubt that this alone (weak battery) would cause a lower voltage while the altnernator is running, unless the battery is presenting such a large load to the alternator that it (the alternator) cannot supply the other electrical needs of the car as well. This could explain why you see a lower voltage than you'd normally see at idle. I'd check both the battery and alternator to be sure.

While I don't have any figures, I don't believe that leaving the lights on for only an hour should drain it so much that it wouldn't be able to start the car, especially during the summertime. I would think that you should easily be able to leave them on for 5-7 hours or more. But an hour is way too short. Perhaps someone else can provide us with some "real world" figures on how long a stock-size battery in good condition will power the lights and still have enough capacity to crank the engine...

[This message has been edited by Stuart Moss (edited July 06, 2001).]

 

Wow Stewart, thanks for the detailed response. I'll load check the battery, check current output and report back very soon.

 

650RPM is a little low for an idle speed. You are right near the bottom limit for the operating speed of the alternator. The alternator is going to fall flat on its face at that RPM. Try 800RPM and you should find it improves. By 1500RPM you are giving the alternator something to work with and its current output is rising. If the 800RPM idle still doesn't satisfy you the only other option is to go aftermarket for a larger alternator. Simply put, it isn't broken. The only other suggestion I can make is to try to find a smaller pulley for the alternator. This will spin the alternator faster allowing it to produce more current at the same engine speed.

[This message has been edited by Grand Prix (edited July 07, 2001).]

 

650 is the idle speed as determined by the computer. It cannot be adjusted unless you change the chip.

I might try to raise it since I can burn my own chip. Worth a shot anyway.


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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project

 

Well, today I changed the idle speed to 800 in the prom. I'll let you know tomorrow how it performs.
Also I checked the current output of the alternator with a clamp on DC ampmeter(not an AC one), I got 22 amps from the alt with a draw on the battery of 7 amps at idle unloaded.
Next I applied a full system load, again at idle I am measuring 65 amps from the alt and a draw on the battery of 32 amps, thats a draw not a charge in both cases. Why? Why is the battery being forced to supplement the alternator while running? I have always thought the alternator was to provide total system power and charge the battery.
All tests were done with a idle speed of 800rpm's and a brand new battery.


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86 Camaro Sport
383 Speed-O-Motive Crate Engine, Raptor 700R4 Tranmission, Trick Flow Twisted Wedge G2's, 58mm Accel TB, 3.73 Auburn Pro, SLP Cold Air Induction and Headers, Hooker Cat-back, Serpentine Belt Setup, Dual IROC Fans, Jamex springs, 16" IROC Rims, 36mm/24mm Sway Bars, Global West Steering Brace. Hotchkis Rear LCA's,Panhard Bar and SFC's.
My Camaro Project

[This message has been edited by John Millican (edited July 11, 2001).]