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May have a 12v problem

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by jefe, Jun 12, 2013.

  1. jefe

    jefe Member

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    Having just replaced my HV battery, I think I may need to now replace the 12v.
    Last night the negative terminal popped off as I pulled into my driveway. Everything went black which is kind of frightening.
    I tightened the connection (I had recently disconnected it and didn't tighten it back enough. ) so I decided to run some voltage testing on it this morning. First test pre ready was 11.6 v. Then ready measured 12.1. When I drive it shows 13.9.
    These are all scanguage readings. Thoughts?
     
    #1 jefe, Jun 12, 2013
  2. dorunron

    dorunron Senior Member

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    Jefe,

    I know you have the scanguage.

    Run the test that is linked below and post all three values please. Also let the Prius set for at least eight hours (overnight) before you run the test.

    Weird stuff happening? MPGs dropping? Test The Battery | PriusChat

    Good luck to you!

    Ron
     
    #2 dorunron, Jun 12, 2013
  3. jefe

    jefe Member

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    11.9
    11.6
    14.1
     
    #3 jefe, Jun 13, 2013
  4. boppo

    boppo Active Member

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    Maybe u should charge the battery first since the cable was not on tight. Then check it a few days later and c what the test gives u.
     
    #4 boppo, Jun 13, 2013
  5. bisco

    bisco cookie crumbler

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    if it's the original, change it anyway before you get stranded somewhere.
     
    #5 bisco, Jun 13, 2013
  6. dorunron

    dorunron Senior Member

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    Definitely weak, but charging it might help. I was seeing similar numbers last summer. Ended up changing it in the middle of winter.

    I would charge it up and see if it will hold a charge. If not, then I would change it. EDIT: Make certain that you use a charger that has a AGM setting. Use that setting for the correct charging algorithm. If you use another setting like gel or flooded, the AGM battery will NOT be fully charged when the charger shuts off or goes into standby/maintenance (trickle) mode. (End Edit)

    FWIW, a fully charged AGM type battery will read the following when running the test.

    Accessory Mode: 12.6 or higher
    Ignition On Mode: 12.4 or higher
    Ready Mode: 13.8 - 14.2
     
    #6 dorunron, Jun 13, 2013
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