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Thread: High Voltage

  1. #1
    Jr. Engineer BRB46's Avatar
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    Default High Voltage

    Just want to know what voltage is considered to high. I know fluctuations are normal but over the last couple weeks mine on the factory volt meter is above 14. So i installed a digital voltmeter and it is reading 15.5v at idle and up to speed. That seems too high. I also get a warning chime randomly but no info on the DIC and no other warning lights. Don't know if they are related. It is an aftermarket NAPA reman alternator which has been installed for almost 2yrs. I believe the stock one was 105amp and this one is suppose to be the same. Should I replace it or is there no need for concern. Don't want an electrical fire. Occasionally it would run that high but then settle down just a bit over 14 and sometimes under.
    2006 Silverado 1500 5.3L ecsb Z71,afe pro s dry air filter, color matched tailgate handle and bezel,color matched front bow tie, led interior illumination, 5000K HID lows, Black powder coated wheels, Blacked out body side moldings, Rough Country 2.5" level/lift kit, Magnaflow muffler

  2. #2

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    Sounds like the alternators internal voltage regulator is going or gone bad, along with dangerous spikes to electrical parts on the truck you also have a very real probability of overcharging the battery and getting a battery melt down.

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    Jr. Engineer BRB46's Avatar
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    Thanks. That doesn't sound too safe. Looks like I should swap it out. Well I just swapped out the alternator and the voltage dropped down to 13.2v. I didn't drive it yet but ran up the RPMs to 1500 for a couple minutes while switching loads on and off. It started at 15v and slowly dropped down to 13.2. I presume because battery was slightly over charged. So hopefully that will solve the issues. Thanks.
    Last edited by BRB46; 01-26-2014 at 02:15 PM. Reason: Update
    2006 Silverado 1500 5.3L ecsb Z71,afe pro s dry air filter, color matched tailgate handle and bezel,color matched front bow tie, led interior illumination, 5000K HID lows, Black powder coated wheels, Blacked out body side moldings, Rough Country 2.5" level/lift kit, Magnaflow muffler

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    My 2013 camaro stays around 15.4v, I bought it brand new and it's always been like that. But it's better to be safe then sorry, I've had an engine fire before and they're no fun lol!
    2004 Chevy Colorado
    LS1 5.7 swap/TBSS rear axle swap

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    Jr. Engineer BRB46's Avatar
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    My son took it after I swapped out the alternator and in 20 miles it stayed at 13.2v and the chime didn't go off one time. So I guess it must have been the high voltage that it was warning me about.
    2006 Silverado 1500 5.3L ecsb Z71,afe pro s dry air filter, color matched tailgate handle and bezel,color matched front bow tie, led interior illumination, 5000K HID lows, Black powder coated wheels, Blacked out body side moldings, Rough Country 2.5" level/lift kit, Magnaflow muffler

  7. #6

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    A fully charged lead acid battery cell should have a voltage reading of 2.1 volts, 6 of them in an automotive battery should read (at rest) 12.6 volts.

    A properly regulated alternator will out put a max voltage of 14.4 to 14.6 volts while charging; and it may drop to 13.2 while maintaining the charge.
    Ray

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

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    Jr. Engineer BRB46's Avatar
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    Quote Originally Posted by RayVoy View Post
    A fully charged lead acid battery cell should have a voltage reading of 2.1 volts, 6 of them in an automotive battery should read (at rest) 12.6 volts.

    A properly regulated alternator will out put a max voltage of 14.4 to 14.6 volts while charging; and it may drop to 13.2 while maintaining the charge.
    That's what I would have thought to be normal. The needle on volt meter always ran just above 14 and lately it was just about to the next mark up. I knew something wasn't right with it. Thanks for the info.
    2006 Silverado 1500 5.3L ecsb Z71,afe pro s dry air filter, color matched tailgate handle and bezel,color matched front bow tie, led interior illumination, 5000K HID lows, Black powder coated wheels, Blacked out body side moldings, Rough Country 2.5" level/lift kit, Magnaflow muffler

  9. #8

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    Quote Originally Posted by BRB46 View Post
    Just want to know what voltage is considered to high. I know fluctuations are normal but over the last couple weeks mine on the factory volt meter is above 14. So i installed a digital voltmeter and it is reading 15.5v at idle and up to speed. That seems too high. I also get a warning chime randomly but no info on the DIC and no other warning lights. Don't know if they are related. It is an aftermarket NAPA reman alternator which has been installed for almost 2yrs. I believe the stock one was 105amp and this one is suppose to be the same. Should I replace it or is there no need for concern. Don't want an electrical fire. Occasionally it would run that high but then settle down just a bit over 14 and sometimes under.
    does that truck have the variable voltage system? I can't remember what it is called. My 05 has a hall effect sensor around the negative cable. It is supposed to tell the pcm what demands for voltage are and adjust the alternator output accordingly. My voltage runs high driving in the city, but when I get on the highway it drops significantly.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

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    Jr. Engineer BRB46's Avatar
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    Quote Originally Posted by Pikey View Post
    does that truck have the variable voltage system? I can't remember what it is called. My 05 has a hall effect sensor around the negative cable. It is supposed to tell the pcm what demands for voltage are and adjust the alternator output accordingly. My voltage runs high driving in the city, but when I get on the highway it drops significantly.
    Well that's a good question. I guess I will look to see if I can find something out about that. Never heard of anything like that though.
    2006 Silverado 1500 5.3L ecsb Z71,afe pro s dry air filter, color matched tailgate handle and bezel,color matched front bow tie, led interior illumination, 5000K HID lows, Black powder coated wheels, Blacked out body side moldings, Rough Country 2.5" level/lift kit, Magnaflow muffler

  11. #10

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    Quote Originally Posted by BRB46 View Post
    Well that's a good question. I guess I will look to see if I can find something out about that. Never heard of anything like that though.
    This is a long read, Just scroll to the bottom section: http://www.motor.com/article.asp?article_ID=1606

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

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