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Discussion Starter #1
2008 Colorado 3.7, was driving and got an alarm from my ultra gauge my output voltage was too high, runs between 13.5v to 15.5v, took to a battery shop they said I had one bad cell so I replaced the battery (5 years old) after replacing the battery I didn't receive errors for about 200 miles whereas before changing the battery I would get an alarm about every 5 minutes. Well after a couple of weeks I'm back to the errors. Is this something I should address? is it just the way my ultra gauge is set up? Is 15.25 volts too high? It will bounce between 14v to 15.25 now. Any ideas?
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Mines never been above 14s in my canyon or s10. On my scan gauge 2


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My voltage has never been above 14.2 on my Colorado. The only thing I can think of is the voltage regulator in the alternator is bad. I'd take it to an auto parts store and have them check the alternator output. Here's a quick video that might help:
If you have a starter/alternator shop near you, they can probably replace the regulator without having to spend the $200+ for a new or rebuilt alternator.
 

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On my 2008 Colorado LS, the voltage sometimes hits 14 (strange, but it only does this in cold weather and just after starting until it warms up) - So I reset the alarm point on my Ultra Gauge to 14.1 and now I don't get alarms any more, but I would still be notified on 14.1 or more.
 

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Like the video says, 13.8 - 14.2 is the normal range. With all the electronics on newer vehicles, the truck will start with 12v, but it won't run very well with only 12v. When my alternator went bad about a month ago, when my Scangauge II got just below 12v, the A/C stopped working then the stereo stopped working, then all gauges stopped working and the truck started running very poorly.
I'm afraid that if you run this alternator too long, you'll continue to burn up batteries.
 

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Mine will fluctuate depending on the charge state of my battery... When my battery is topped up properly, it will run between 12.75v (on a long drive) and 13.5v... If my battery is needing a charge, it will run higher, 14.5 to a little over 15v. When I start up in the morning in the winter time, it usually peaks over 15v until things warm up.
 

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Checked today in my s10. When it was all day cold. It did hit a high of 14.8. So t have the canyon anymore. But I’d think alternators should be mostly the same kind of valtage output


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Discussion Starter #8
Thank you all so much! tested a bit more today, upon first start up (in garage about 40 degrees) would fluctuate from 14 to 15.05, after warm up it would fluctuate from 13.95 to 15v, It can be around 14.8 v with all accessories off, turn on lights and heater within 5 minutes will slowly return to 13.95 to 14.15v, tried this several times with the same results.
Is it typical for the voltage to bounce around from 14.5v then jump to 14.75 then down again, constantly changes.
 

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I’d say you’re probably ok

Mine fluctuates in both vehicles


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I have a voltage gauge on the dash that displays into hundreths of a volt .... Mine runs at almost exactly 12.78v when the battery is charged up all the way on a long drive... But any other time, you would be amazed at how much it fluctuates all the time!
 

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Mine has gotten as high as 14.5V, but it does fluctuate quite a bit. At idle it stays at 12.X to 13.X, always below 14. Never thought much about it. When I bought the truck in 2012 it still had the original battery in it. I had to replace it in 2013, and that new battery is still going strong. I can't imagine ranges in the mid 14's are bad for batteries with that kind of longevity.
 

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Discussion Starter #12
Update: It's not uncommon not to drive the truck for 3 or 4 day's this is when I have the high voltage, however the last few day's I've driven every day now it's reading between 12.5 to 13.5, seems I need to drive it more often.
Thanks everyone!
 
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