Battery voltage at 11 constantly even after new battery/alternator

GNbythebay

Member
Jul 28, 2016
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Recently I bought a new battery and not even a few days later it was dead. I thought maybe it was just a bad battery so I warrentied and got another new one. Same thing happen! Took my alternator to get it tested and I was told it was dead. I now have a new battery and alternator and on my scanmaster the battery stays at 11-11.8. I’m pretty sure it is suppose to be at 13.5-14. Can anyone give me suggestions of what the problem really is.
 

seedling

Well-Known Member
Jun 17, 2012
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Baton Rouge, LA
if the bulb is burned out on your volt light in the dash, then the alternator won't charge the battery . also if there is a bad connection/wire to this volt light indicator in the dash
Wow! Had no idea about the light in the dash affecting the alternators charge to the battery! That’s good to know there!

OP if that doesn’t work then you might go through some of the checklists on line. Here’s one that might help:

https://www.vortexbuicks-etc.com/troubshootgeneral.htm



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grass doctor

Active Member
Sep 21, 2018
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saint augustine fl
Caspers makes a new upgraded electrical ribbon that goes on the back of the dash cluster that eliminates this design flaw
they also make a cheaper easier plug and play ( field fix wire) to help maintain proper voltage
 

michael evans

Active Member
Feb 27, 2008
808
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Louisville, Kentucky
Look at you pulley's diameter (crank and alternator).

Might not not be spinning the alternator fast enough.

Mine was stuck at 12.7 volts and I had to change my alternator pulley to correct it.
 

RmvBfrFlght

Well-Known Member
Sep 28, 2007
2,104
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Here is a post that lists how to get the most out of the alternator. And fixes the dreaded 'bulb out' no charge failure.


RemoveBeforeFlight
 

BMR

Bad Medicine Racing
Jul 26, 2009
239
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I have also seen the main wire from the alternator to battery deteriorate and cause a no charge condition.
 

TexasT

Texas, Where are you from
Sep 10, 2002
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You post the battery is at 11.8, did you test the post on the back of the alternator to see if it is putting out voltage(with the engine running)?

If so, already posted the casper fix, but if not the alt might not be functioning as Earl pointed out.

Does the light on the dash light up when you turn the key to run before engaging the starter?
 
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GNbythebay

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Jul 28, 2016
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You post the battery is at 11.8, did you test the post on the back of the alternator to see if it is putting out voltage(with the engine running)?

If so, already posted the casper fix, but if not the alt might not be functioning as Earl pointed out.

Does the light on the dash light up when you turn the key to run before engaging the starter?
I’m getting no power from the red alternator wire when the car is on and I do not see the dash light when I turn the key to the on position. Only light that pops up is the fasten belts bulb
 

ScottHeidinger

Active Member
May 2, 2015
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I’m confused. If you take the connector off of the alternator with the key on do you have voltage on the brown wire?
The red wire on the back of the alternator runs to the positive battery post so even if the alternator isn’t working you should have voltage from the battery?


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GNbythebay

Member
Jul 28, 2016
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I’m confused. If you take the connector off of the alternator with the key on do you have voltage on the brown wire?
The red wire on the back of the alternator runs to the positive battery post so even if the alternator isn’t working you should have voltage from the battery?


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I had a test light hooked to the red wire on the alternator side and got nothing. But when I connected it to the red wire on the battery side it had power.
 

ScottHeidinger

Active Member
May 2, 2015
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northeast Florida

I would read the information in this link. There is a link from John that explains the alternator dash light in detail and there are 2 pages of potential issues that are common with these cars. At over 30 years old wire issues are common as well as corrosion on the back of the gauge cluster connector.

The voltage or lack of voltage at the brown wire at the alternator connector will help us help you.


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ScottHeidinger

Active Member
May 2, 2015
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northeast Florida
You can buy the little alternator pigtail at a auto parts store and wire a 480 ohm resistor or a light socket with the same bulb that is used for the alternator idiot light in series to the battery. If the alternator works properly with this then you know it’s a wiring issue. Don’t connect the brown wire to 12 bolts without a bulb or resistor in line or you will kill the alternator.


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