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Battery gauge movements

Discussion in '2nd Gen Tundras (2007-2013)' started by Lineman4x4, Oct 5, 2019.

  1. Oct 5, 2019 at 5:24 AM
    #1
    Lineman4x4

    Lineman4x4 [OP] New Member

    Joined:
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    Vehicle:
    2009 5.7 4wd
    Hi guys, 2009 4x4 , 85,000 miles, knock on wood no major issues. However, last year I replaced alternator and battery, ( alt went on me , ) truck been running find, no dimming lights, etc, but I notice the battery gauge drops a volt or 2 when lights are turn on, then goes right back up to normal , also when I'm driving around at high speed/rpm, and come to a quick stop , ( when rpm come lower) the battery gauge will do a quick 2 volt dip, then back to normal.
    It never dips below say 2 line from middle of gauge, but still curious why it would dip at all??
     
  2. Oct 5, 2019 at 6:08 AM
    #2
    Rubberdown

    Rubberdown Spilling my guts here.

    Joined:
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    Houston, TX
    Only a couple of choices. In no particular order:

    Bad cell in battery

    Bad regulator in alternator

    Bad grounding.
     
  3. Oct 5, 2019 at 6:09 AM
    #3
    JohnLakeman

    JohnLakeman Burning Internet Daylight

    Joined:
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    Outside of Weird, TX
    Vehicle:
    2017 MGM DC TSS 4.6L
    TRD Pro grille, 2018 LED Headlights, Undercover Flex bed cover, Neoprene seat covers, Bed/tailgate mats, Power tailgate lock, auto headlights, illuminated key switch
    The first question everybody will ask here...how old is the battery (when was it changed)?

    The charging system is not responding instantaneously to the sudden load changes. The battery is often the culprit, and that's the easy fix. Batteries are not what they used to be. But, it could also be the alternator, because charging rate is controlled there.
     
  4. Oct 5, 2019 at 6:24 AM
    #4
    Lineman4x4

    Lineman4x4 [OP] New Member

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    Both replaced new 1 yrs ago.
    Maybe I'll start with a better , stronger battery
     
  5. Oct 5, 2019 at 9:53 AM
    #5
    JohnLakeman

    JohnLakeman Burning Internet Daylight

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    Outside of Weird, TX
    Vehicle:
    2017 MGM DC TSS 4.6L
    TRD Pro grille, 2018 LED Headlights, Undercover Flex bed cover, Neoprene seat covers, Bed/tailgate mats, Power tailgate lock, auto headlights, illuminated key switch
    You should get more than a year out of a battery. You might look at getting it tested or buy a tester before you buy a battery. Auto part stores can test them for you, but I am always skeptical where the tester also has a vested interest in selling a new one. Often, their tester is old technology that really doesn't provide a good test. I bought this to keep an eye on my battery health with semi-annual tests. The new batteries more often seem prone to sudden failure by dead cell; fine one moment, core credit the next.

    https://www.amazon.com/gp/product/B01M0ARG3X/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
     
  6. Oct 5, 2019 at 10:59 AM
    #6
    Lineman4x4

    Lineman4x4 [OP] New Member

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    Male
    Vehicle:
    2009 5.7 4wd
    Just got back from auto zone, all test passed. From battery, to starting truck, to putting on lights,heater etc. It showed a small dip in voltage, I think 12.3 volts, but all looked good per auto zone tech
     

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