GM Truck Club
Founded in 2004 ~ We're the #1 Chevy Truck & SUV Forum.
Silverado & Sierra | Tahoe & Yukon | Suburban & Yukon XL | SUV & CROSSOVER
Page 1 of 2 12 Last Post byLast Post by
Results 1 to 10 of 16
  1. #1

    Default Battery voltage gauge seems inconsistant

    Hey all. I am new to this site and recently purchased a 2012 Silverado Z-71 with the All Star Edition. I noticed my battery gauge needle is moving more than I have ever seen one move before. It appears the needle fluctuates between 12 and 15 or volts. The battery gauges on most vehicles I have owned stays around 13 to 14 volts and doesn't move much unless something that consumes a lot of power is turned on. Mine does this with nothing additional running on the truck other than the radio and a/c.

    This morning the needle was about 1 volt below (13 volts) the middle mark (14 volts) on the gauge. I noticed it, turned the truck off, restarted the truck and the needle went about 1 volt above (15 volts) the middle mark of 14 volts.

    Has anyone else noticed this in their trucks?

    BTW, this won't be my first post, gain info, then bail out. Someone pulled out in front of me and totaled my 84 GMC truck. I was/am very active in another forum that was started primarily for older trucks. Nonetheless, that truck is gone and I am looking for new forums to get involved with that have lots of info for newer trucks.


  2. #2


    Jeremy if you look in the owners manual it can explain the system much better than I can but your 2012 truck has a variable charging system that only produces the current needed to operate electrical systems on at any one time and perform a trickle charge/maintenance charge on the battery.
    If I remember the section your looking for will either be labled "Charging system", or it might be under the gauge description.

  3. #3


    Thank you for your response! I didn't read the manual word for word from cover to cover, but I did spend about 15-20 minutes skimming through it. I just now found the section that discusses this on page 5-18.

  4. #4


    My 05 does the same thing with a new alternator and battery. In the city it is around 14 volts, when I get on the highway it drops to 11-12 volts. If I put all 4 windows up at the same time the lights dim for a second and then the voltage goes up to 14-15 volts. As soon as I let go of the buttons it drops back to 11-12
    Last edited by Pikey; 10-02-2012 at 08:44 AM.

    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,
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  5. #5

    Join Date
    Sep 2010
    everett, massachusetts


    the guage on my 2000 silverado and the 2002 stays at the 14 volt point with the engine running and very rarely moves off this reading.

    when the alternator regulator started to go the voltage would drop to just above 12 volts then jump back to 14volts.

    Using a dc volt meter measure the alternator output voltage, compare with the dash guage.

    load up the electrical system all on see if it holds or drops.

    just because its new does not mean the battery is good, or the connections to it are in need of cleaning and securing.

    could also be a defective alternator,dash guage, or wiring.

  6. #6


    Both my 2012 and my buddy's 2012 do the same thing.... dealer explained to him that it is a fuel saving feature.... alternator only runs when required then shuts down to save load on vehicle and thus better gas mileage.... hope their right.

  7. #7

    Join Date
    Sep 2010
    everett, massachusetts


    the load on my 2000 SIL is about 66AMPS with the engine running . If the alternator cycles on and off the Battery is going to suffer.

    I guess it is possible the alternator output is throttled to limit its output and reduce load on the engine. that would not save you much on power/MPG.

    If true this would be something to check out.

  8. #8


    My 2012, 1500 5.3l with less than 1K miles also does this. The seond day of ownership the battery died becuse it wouldn't hold a charge and was replaced by the dealer. I then noticed that the voltage at times would be around 13 volts. After restarting the engine it would go to the 15 volt area. The manual is 584 owner manual size pages in pdf format. About 240 pages in standard 8.5'x11" and I havn't had time to read all of it. I'm glad I joined this forum for it saved me a trip to the dealer.

  9. #9

    Join Date
    Sep 2010
    everett, massachusetts


    with your dash guage readings it is quite possible they have a bad batch of alternators. high voltage will also damage a battery as well as the electronic devices/PCM.

    15volts would be if it was zero deg F air temp on a cold start. this woulld only be at that amount for a short time. the higher voltage heats up the battery quicker. a battery must be warm to accept a charge.

  10. #10


    I also have read (I believe in the owners manual) that the charging system does vary. I have noticed that my 2011 does do this so what you are describing is normal. I am sure that there are not a bad batch of alternators as someone has previously suggested.

    2011 Silverado CrewCab 5.3L*Ram Air Look Cowl Induction Reflexxion Hood*6" Pro Comp Lift*Flowmaster Dual exhaust*Perfect Launch Rear Diff. Cover*Led Smoke Taillights*L.E.D.Smoke 3rd Brakelight*60" L.E.D. Tailgate Bar*Rearview Mirror Reverse Camera and Sensors*Smoke Headlight Covers*Front Bumper Grill Insert*Deezee Black Alum. Diamond Rail covers*20" Ultra Motorsports Rims wrapped with 35.5"B.F. Goodrich Tires*Inchannel Raingaurds*CAI*Bullydog GT Tuner*Alpine Amp*Boss 6x9's*Boston Acoustic Subs*Terrantula Tweeters*Custom Sub box*Red Led Interior Accents*5% Ultimacool duo tint rear window and doors, 20% front doors*Custom Vinyl Graphics*Demolded*Debadged*Painted drums and calipers*
    Future Mods Include: Custom Interior Hydrographics, Electronic Rollup Toneau Cover, 4.56 Gears, Painted rear bumper

Page 1 of 2 12 Last Post byLast Post by

Similar Threads

  1. Voltage Gauge fell over?
    By Bama Z71 in forum GM Electrical Tech
    Replies: 8
    Last: 02-06-2011, 10:15 PM
  2. battery gauge malfunction
    By britrailer in forum Chevy Silverado Forum (GMC Sierra)
    Replies: 9
    Last: 11-29-2010, 01:25 PM
  3. Voltage gauge issue/question
    By hihoslva in forum Chevy Suburban Forum (GMC Yukon XL)
    Replies: 6
    Last: 04-12-2010, 08:03 PM
  4. battery voltage reading
    By cordgrass in forum General Chevy & GM Tech Questions
    Replies: 3
    Last: 03-15-2010, 09:40 AM
  5. help 98 s10 battery draining low voltage
    By noahraysanders in forum Chevy S10 Forum (GMC Sonoma)
    Replies: 1
    Last: 12-03-2009, 10:56 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts