Gain extra benefits by becoming a Supporting Member Click here find out how!

Classic Performance Products Nu-Relics Power Windows
American Auto Wire Hellwig Products IncPerformance Rod & Custom
Danchuk Catalog



Username Post: What is Happening...Alternator Voltage Too High?        (Topic#205946)
vabeach56wagon 
Valued Contributor
Posts: 3157

Loc: Chesapeake,VA,
Reg: 04-22-02
12-26-08 10:58 AM - Post#1592919    

With the 327 in it finally, the Gob has now spent several days on the road...

Good news: No leaks, other than some of my bad welds on the exhaust, which I planned to address this weekend.

Bad news: the battery (brand new) has puked acid into the tray and down onto top surface of frame, headers, stainless fuel line...

Good news: I noticed it before it was really, really bad...

Bad news: Cleanup and spot repaint are necessary, now that I've neutralized acid with a spray down of baking soda...the headers will need recoating.

Good news: ??

Question of the day: Can a battery be defective and not take the 14 volts the alternator puts out thereby cooking the fluid as in an overcharge?

2nd question of the day: I think the battery is OK but the alternator may be cranking out too high a level of voltage. How do I check out the alternator without putting the battery back in the car and firing it up?

Paul

Original builder of the Gobstomper - '56 210 9 passenger wagon now in other's hands. Current Ride is Porsche 911 cabriolet and 1931 Chevrolet Independence Sport Coupe (19,000 documented original miles).



 


Jalapeno 
Member #252
Posts: 9917

Loc: The Hill Country of Texas
Reg: 04-30-00
12-26-08 11:01 AM - Post#1592921    
    In response to vabeach56wagon

Paul, the battery is being overcharged, boiling the acid. Possibly the alternator is stuck wide open because of a short. Take the alternator to a place that can test it, like an alternator/starter rebuild shop.

Jalapeno


 
awsum55 
Senior Member
Posts: 8872
awsum55
Age: 72
Loc: O.P. Kansas
Reg: 09-27-01
12-26-08 11:02 AM - Post#1592924    
    In response to vabeach56wagon

You can use jumper cables to fire the car and then remove them. The alt will keep the car running and then you can test it out.

Five things that you cannot recover in life:

* The Stone after it's thrown
* The Word after it's said
* An Occasion after it's missed
* The Time after it's gone
* A person after they die


 
Old_Longboarder 
Deceased Member RIP Art
Posts: 12969
Old_Longboarder
Loc: GOD's Garage
Reg: 03-28-02
12-26-08 11:02 AM - Post#1592925    
    In response to Jalapeno

What type of alternator? Is is wired correctly?

Home.., is where dog hair sticks to everything but the dog.





 
acardon 
Ultra Senior Member
Posts: 11489

Loc: DFW TEXAS
Reg: 03-25-05
12-26-08 11:09 AM - Post#1592930    
    In response to Old_Longboarder

Old Longboarder has a good point. If it's a 3 wire alternator and the #2 alternator terminal is not connected to battery voltage, the alternator will never shut off and keep chargeing. #2 terminal is for voltage senseing.

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
Old_Longboarder 
Deceased Member RIP Art
Posts: 12969
Old_Longboarder
Loc: GOD's Garage
Reg: 03-28-02
12-26-08 11:17 AM - Post#1592944    
    In response to acardon

The #2 terminal is the field terminal which should have 12 volts at all times.

The #1 terminal is the excitement/switch terminal which must go through a alternator/generator light bulb or be wired with resistance wire to operate correctly.

If the #1 terminal has a full (switched) 12 volts to it, the alternator will charge fully at all times.

Home.., is where dog hair sticks to everything but the dog.





Edited by Old_Longboarder on 12-26-08 11:20 AM. Reason for edit: No reason given.

 
Gray Headed Mule 
Valued Contributor
Posts: 4736
Gray Headed Mule
Loc: Fort Worth, Texas
Reg: 12-11-03
12-26-08 11:26 AM - Post#1592952    
    In response to Old_Longboarder

Doesn't a bad ground cause the alternator to charge excessively?

Mule

I'm sexy and I know it!

My 49 Chevy Fleetline Deluxe Restoration Project


 
raycow 
DECEASED
Posts: 27999
raycow
Loc: San Francisco, CA
Reg: 11-26-02
12-26-08 12:55 PM - Post#1593022    
    In response to Gray Headed Mule

#1 is the alternator "turn on" terminal. Once the alternator begins charging you can disconnect that wire and it will continue to charge until you shut off the engine.

#2 is the voltage sensing terminal and MUST be connected to battery voltage or else the alternator will definitely overcharge the battery.

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
vabeach56wagon 
Valued Contributor
Posts: 3157

Loc: Chesapeake,VA,
Reg: 04-22-02
12-26-08 02:24 PM - Post#1593086    
    In response to Old_Longboarder

At my local parts house bench tester , the alternator tested out OK...16 volts steady on the machine, no warning or defective lights...but that was at a steady speed...this little motor sees the sunny side of 6500 r's whenever I take it out on the street...could that be part of the problem?

this is a 3-wire, been on the Gob since 2005...same wiring harnesss since 2005...no changes other than the new battery and the engine...never had any problem prior to this time...

I wired the car to allow relatively easy removal of the front clip...no through the firewall wiring...all quick-disconnects...all coded or sized to avoid my inevitable screw-ups...

The parts guy will let me have a replacement alternator to try out on the street...

Could the higher RPM level (I had the 383 with its hydraulic roller chipped at 6200)of the 327 (chipped at 6700) make that much, if any, difference?

Paul



Original builder of the Gobstomper - '56 210 9 passenger wagon now in other's hands. Current Ride is Porsche 911 cabriolet and 1931 Chevrolet Independence Sport Coupe (19,000 documented original miles).



 
acardon 
Ultra Senior Member
Posts: 11489

Loc: DFW TEXAS
Reg: 03-25-05
12-26-08 03:37 PM - Post#1593131    
    In response to vabeach56wagon

  • Quote:
16 volts steady on the machine,



16 volts is too much. The question is, will the internal regulator cut the voltage to 12.6 when the battery is fully charged. Usually around 14 volts is tops to charge a battery. I don't think the extra RPM is aproblem. I doubt that 6700 RPM is maintained for long enough to hurt the alternator. I would try the other alternator.

Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


Edited by acardon on 12-26-08 03:40 PM. Reason for edit: No reason given.

 
52chevybob 
Dedicated Enthusiast
Posts: 5628

Reg: 05-27-08
12-26-08 09:45 PM - Post#1593342    
    In response to acardon

Proper charging voltage is 13.8V. If your internally regulated alternator is putting out 16CV thenn it is bad. That muc voltage ouptut will fry a battery in no time. The battery will hold to about 14V for a while and then gradually go up from there. As it does so,m the alternator will be putting out its full charge rate and you will heat the battery a whole lot.



 
Old_Longboarder 
Deceased Member RIP Art
Posts: 12969
Old_Longboarder
Loc: GOD's Garage
Reg: 03-28-02
12-27-08 07:35 AM - Post#1593466    
    In response to vabeach56wagon

If your alternator isn't wired like this, it will not work correctly. Note the lamp and resistor.
This is an either/or, you don't need both. Sorry, but I don't know what resistor would be used.

I do now! Thanks to Google.

10 ohm wire wound ceramic resistor (Radio ShackŪ part No. 271-132)

Get 12 volts for the #2 terminal at the nearest source, the battery terminal on the alternator.



Home.., is where dog hair sticks to everything but the dog.





Edited by Old_Longboarder on 12-27-08 07:47 AM. Reason for edit: No reason given.

 
BIG AL 
Senior Member
Posts: 223

Loc: WA
Reg: 11-25-04
12-27-08 08:12 AM - Post#1593478    
    In response to vabeach56wagon

Sounds like the alt. is putting out to much. On my 55 it puts out around 14 volts which it seems to be ok for the last four years. I did have a NAP? battery in at first which shorted out with in a year and leaked just like yours did. Put in different battery and it took care of the problem. Son also bought a NAP? battery for his S-10 and did the same thing with in a year. No more Nap? batteries for us.



 
MikeB 
Ultra Senior Member
Posts: 10073
MikeB
Loc: Plano, TX
Reg: 08-28-03
12-27-08 11:10 AM - Post#1593566    
    In response to Old_Longboarder

Paul, When connected to the battery, most alternators will put out around 14.2 volts. Maybe yours putting out 16 volts is a function of the load the auto parts store connected it to. If it was doing that in your car, it's too high. As I recall, this can indicate a bad internal regulator.

  • Old_Longboarder Said:
If the #1 terminal has a full (switched) 12 volts to it, the alternator will charge fully at all times.


You can also use a diode (in lieu of ALT/GEN lamp or resistor) between 12 volt IGN and the #1 ALT terminal. This puts 12 volts on the #1 terminal, but keeps the alternator from feeding back 12 volts to the ignition circuit with the ignition switch turned off.

Nice drawing, by the way. I copied it into Word and saved it.


1982 C10 SWB pickup: Unmolested base truck, original paint. Originally had 250 six and 3-on-the-tree
Now has 355 with Vortec heads, RamJet roller cam, LS6 beehive springs, TH350
Retired, but working part-time on 50s-70s cars & trucks.


Edited by MikeB on 12-27-08 11:13 AM. Reason for edit: No reason given.

 
vabeach56wagon 
Valued Contributor
Posts: 3157

Loc: Chesapeake,VA,
Reg: 04-22-02
12-27-08 05:54 PM - Post#1593734    
    In response to MikeB

I have the diode in the line, and the indicator lamp in the cluster...

When I first bought this battery several months ago, I put the trickle charger on it just to be sure it would be fresh when I stuck it back in the car.

At that time, it boiled over and I attributed that to the trickle charger which has served me faithfully for more than 20 years...and which has a functioning internal regulator to avoid overcharging...

Could there be something wrong with this battery?

I find it hard to believe that the alternator could go bad while sitting in a file cabinet for six months.

Nevertheless, I have replaced it with another fresh unit, which was part of the parts stash for the SBC into the T-Bird project...now to fire it up and see what happens...I'll not do any repaint,etc until I know that the acid bath is no longer occurring. It made a real mess of that area of the frame, headers etc.

Paul

Original builder of the Gobstomper - '56 210 9 passenger wagon now in other's hands. Current Ride is Porsche 911 cabriolet and 1931 Chevrolet Independence Sport Coupe (19,000 documented original miles).



 
Rick_L 
Member #409
Posts: 28115
Rick_L
Loc: Katy, Tx, USA
Reg: 07-06-00
12-29-08 07:47 AM - Post#1594620    
    In response to vabeach56wagon

If you have an internally regulated alternator that is putting out 16 volts, that is too much. That will boil the fluid from the battery and will eventually burn out all your light bulbs.

The solution is to replace the regulator or the whole alternator.

If you have an externally regulated alternator, you have regulator problems, and the regulator should be repaired or replaced.

As the others already said, you should be seeing 13.8-14.2 volts at the output terminal.

The wire with the diode or charging indicator bulb has nothing to do with this problem.



 
vabeach56wagon 
Valued Contributor
Posts: 3157

Loc: Chesapeake,VA,
Reg: 04-22-02
02-02-09 03:16 PM - Post#1621144    
    In response to Old_Longboarder

Bear with me on this for a minute, because I am now totally confused. I have a brand new battery, a brand new alternator and a wiring problem which I will tackle this week if I can get it through my thick skull exactly how to run the wiring:

From battery post on alternator, can I go to the horn relay? and will that suffice for that component of the alternator wiring?

From #2 terminal can I also go to horn relay, or to the ignition switched distribution block on the firewall?

For #1 terminal: I have the resistor in the line just off the alternator...then it runs to the indicator lamp and then to the ignition switch...WHICH ignitions switch post does this lead run to? and which post does the indicator lamp lead run to....

This is where I've screwed up, and I need to grasp what I've done before I start tearing up the harnesses which are all so nicely wrapped and tucked into position under an assembled dash...

[image]https://www.chevytalk.org/fusionbb/showtopic.php?tid/205946/post/15937 34/hl//fromsearch/1/#1593 734[/image]

If this image doesn't come up, please click on the attachment, or scroll back to Old Longboarder's earlier post...

this whole thing is driving me nuts and I know it's probably a simple fix...or I'll rewire just the alternator to make it work and stop overcharging the battery and spilling acid down on my frame and everything else...

psf





Attachment: AlternatorWiringOverview-1973to1985Buick_1_.jpg (60.12 KB) 464 View(s)

Original builder of the Gobstomper - '56 210 9 passenger wagon now in other's hands. Current Ride is Porsche 911 cabriolet and 1931 Chevrolet Independence Sport Coupe (19,000 documented original miles).



 
acardon 
Ultra Senior Member
Posts: 11489

Loc: DFW TEXAS
Reg: 03-25-05
02-02-09 04:50 PM - Post#1621202    
    In response to vabeach56wagon

  • Quote:
From battery post on alternator, can I go to the horn relay? and will that suffice for that component of the alternator wiring?



Yes, you can go to the horn relay, but if you have a large alternator, I would use a larger size wire to the battery or starter post.

  • Quote:
From #2 terminal can I also go to horn relay, or to the ignition switched distribution block on the firewall?



Yes, you can go to the horn relay red wire or go to the battery post on the alternator. The #2 alternator terminal is voltage senseing. This connection keeps it from overchargeing. If you have a good connection from #2 back to the output of the alternator, and it still overcharges, the regulator in the alternator may be bad.

  • Quote:
For #1 terminal: I have the resistor in the line just off the alternator...then it runs to the indicator lamp and then to the ignition switch...WHICH ignitions switch post does this lead run to? and which post does the indicator lamp lead run to....




You can run the indicator to either "ign1" or the "acc" terminal of the switch. It was originall on the "ign1" terminal.


Don
66 Corvair (driving)
57 2dr HT (driving)
56 2dr HT (waiting to be restored)


 
raycow 
DECEASED
Posts: 27999
raycow
Loc: San Francisco, CA
Reg: 11-26-02
02-02-09 09:50 PM - Post#1621490    
    In response to vabeach56wagon

  • vabeach56wagon Said:
For #1 terminal: I have the resistor in the line just off the alternator...then it runs to the indicator lamp and then to the ignition switch...


You have a problem in this area if you are wanting the warning lamp to work normally. From your description it does not sound like you are following the diagram posted here. If you are using a resistor it should not be connected between the #1 alternator terminal and the lamp. It should be connected between the lamp and the ignition switch exactly as shown.

Ray

Those who choose an automatic transmission want transportation. Those who choose a manual transmission want to drive.


 
vabeach56wagon 
Valued Contributor
Posts: 3157

Loc: Chesapeake,VA,
Reg: 04-22-02
04-05-09 08:06 AM - Post#1669210    
    In response to raycow

A brief report...the resistor which I had in the proper line was broken (too many times on and off during the engine swaps). New resistor swapped in, problem disappeared...

Once again by not looking for the simplest solution first I wasted time and effort.

Thanks for all the advice.

Original builder of the Gobstomper - '56 210 9 passenger wagon now in other's hands. Current Ride is Porsche 911 cabriolet and 1931 Chevrolet Independence Sport Coupe (19,000 documented original miles).



 


Icon Legend Permissions Topic Options
Report Post

Quote Post

Quick Reply

Print Topic

Email Topic

52957 Views
FusionBB
FusionBB™ Version 2.1
©2003-2006 InteractivePHP, Inc.
Execution time: 1.366 seconds.   Total Queries: 16   Zlib Compression is on.
All times are (GMT -0800) Pacific. Current time is 12:08 AM
Top