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Digital USB cigarette plug reads 11.4v when driving

Discussion in '2.5 Gen Tundras (2014-2021)' started by IowaGuy, Jan 31, 2023.

  1. Jan 31, 2023 at 5:16 AM
    #1
    IowaGuy

    IowaGuy [OP] New Member

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    I purchased a USB cigarette adaptor to charge my phone. It has a digital voltage reading on its face and it says 11.4 v while driving. Is this an indication of a bad battery or alternator?

    The adaptor is a cheap Chinese one off scamazon so it might not be accurate and this is in the plug underneath the HVAC controls. It could also be the resistance in the wiring or just a crappy contacts. I guess I need to put my meter on the battery to check it.
     
    Last edited: Jan 31, 2023
  2. Jan 31, 2023 at 5:20 AM
    #2
    Taco-Spike

    Taco-Spike Gateway from Tacoma World ~ ended up here

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    What does the cluster gauge read?
     
  3. Jan 31, 2023 at 5:38 AM
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    Jeff_5_7

    Jeff_5_7 New Member

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    While it is possible the circuit is cheap, voltage is not that hard to measure.

    Get a multimeter set to DC voltage and measure on the battery post with the truck running. You want 13-14v while the truck is idling.

    If you are only getting 11-12v while the truck is running, the alternator is failing.

    Has the truck had trouble starting? Signs of a dead battery? If the alternator really is failing it won’t go very long
     
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  4. Jan 31, 2023 at 5:40 AM
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    Retired...finally

    Retired...finally Utilizing that doctorate of procrastinatory arts

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    ...Cheap Chinese one off scamazon...
     
  5. Jan 31, 2023 at 7:46 AM
    #5
    IowaGuy

    IowaGuy [OP] New Member

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    The voltage gauge on the dash reads right in the middle although that is hardly accurate
     
  6. Jan 31, 2023 at 7:52 AM
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    Tundra234

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    Alot of them
    My Pioneer reads 12.7 and my SG3 reads 13.4 to 13.6 average.
     
  7. Jan 31, 2023 at 7:59 AM
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    MadMaxCanon

    MadMaxCanon New Member

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    Too many, but not enough....
    Mine is about the same. I think the ECU voltage is higher than the "usable" voltage of the truck because of inefficiencies. Just a guess.
     
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  8. Jan 31, 2023 at 8:03 AM
    #8
    MadMaxCanon

    MadMaxCanon New Member

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    Too many, but not enough....
    best way to check the battery i found is put a meter on it and save the minimum reading on the meter, turn on the truck and see what the minimum is. I think anything below 11V means the battery weak.
     
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  9. Jan 31, 2023 at 8:31 AM
    #9
    1lowlife

    1lowlife Toxic prick and pavement princess..

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    What does it read with the engine off?

    Mine reads 13.1 to 13.5 when driving.
    Usually, 12.6 when everything is off.

    aawawv8m_zpsridvswcc_4118b6230759fd2ba4953355028e2667160dfca8.jpg

    Drone app reads 13.9 at idle.

    j06oq9yv_2feb61c2200a1be5c9e270076c139f2054cac0c5.jpg
     
    Last edited: Jan 31, 2023
    NewImprovedRon likes this.
  10. Jan 31, 2023 at 2:52 PM
    #10
    IowaGuy

    IowaGuy [OP] New Member

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    Measurements from the battery posts

    12.38 not running
    13.90 when idling
     
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  11. Jan 31, 2023 at 3:05 PM
    #11
    Jeff_5_7

    Jeff_5_7 New Member

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    Exactly what you want to see. I wonder if the cig lighter ports could be regulated down as well. Seems all anybody uses them for today is phone chargers, of which most are only 5 Volt.
     
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  12. Feb 1, 2023 at 2:45 PM
    #12
    Stumpjumper

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    Best way to test a battery is to load test. In the OPs case I would suspect the cheap Chinese USB adapter is reading incorrectly.
     

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