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12 volt battery seems dead

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Fakhar87, Jun 29, 2020.

  1. Fakhar87

    Fakhar87 Junior Member

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    Hello everyone today i noticed a weired thing with my prius for the first time. I unlocked my car with keyfob and entered the car and inserted the keyfob in the slot and push the start button. Suddenly everything on cluster panel dies out similar to the one with dead battery. I was worried as my trunk was not opening but i managed to open it manually to check the 12 volt battery and just on touching the positive terminal car came back to life. But how on earth my positve terminal looses because i havent touched the battery is it battery problem? Because the no load voltage of battery is 12 volt and on load to 11.6 and with engine running 13.8 volt. Thanking you in anticipation

    Posted via the PriusChat mobile app.
     
    #1 Fakhar87, Jun 29, 2020
  2. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    Could be loose connection. Check voltage with a digital multimeter directly at the battery posts.
     
    #2 Mendel Leisk, Jun 29, 2020
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  3. Fakhar87

    Fakhar87 Junior Member

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    Thanks bro. But any problem in the future? And also tell me thr status of my battery it needs to be changed or what?
    Posted via the PriusChat mobile app.
     
    #3 Fakhar87, Jun 29, 2020
  4. bisco

    bisco cookie crumbler

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    yes, you need a new battery. how did the terminal become loose? probably never tightened properly, and vibration did its job well
     
    #4 bisco, Jun 29, 2020
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  5. SFO

    SFO Senior Member

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    Check and tighten both of the connections at the 12v battery, also check for corrosion where the ground strap is bolted to the car body.

    How old is the 12v battery, and how many hours per week are you driving the vehicle?
     
    #5 SFO, Jun 29, 2020
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  6. sam spade 2

    sam spade 2 Senior Member

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    Are you REALLY saying that you don't believe that a screw/bolt will never work it's way loose just from vibrations and heat and cold ??
    It happens often.

    But your battery voltage readings are a bit low too.
    First clean and tighten both battery cable connections.
    Then drive it for a week or so, let it sit overnight and check the voltage again.
    I suspect you will be needing a new battery SOON.

    P.S. It is also possible that there is a bad connection INSIDE the battery near the positive post.......but that is a rare thing to happen.
     
    #6 sam spade 2, Jun 29, 2020
  7. Fakhar87

    Fakhar87 Junior Member

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    It was from previous owner and it is flooded battery. And i have driven 10k so far. 3 months of lockdown car is in garage but i start it for 5 10 mints after 2 days. And also 50km drive so far in lockdown. Normally my mileage is 300km per week
    Posted via the PriusChat mobile app.
     
    #7 Fakhar87, Jun 29, 2020
  8. Mendel Leisk

    Mendel Leisk EGR Fanatic

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    If it's seeing very little use better put it on a smart charger (owner's manual recommends 3.5 amp max). And do take it for a good drive periodically, say once a week.
     
    #8 Mendel Leisk, Jun 29, 2020
  9. SFO

    SFO Senior Member

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    First clean up and tighten the connections, including the negative ground strap attached to the body.

    Sounds like you're not using the vehicle enough, let it recharge in 'ready' mode for more than 10 mins every 2 days and see if things improve.

    You can check the 'date code' on the top of the 12v battery, if the age is "unknown" it may need replacing, or you can try to recharge it.

    Your terminals/posts might differ, but this thread may be useful : Fitting mobility 12volt AGM battery. | PriusChat
     
    #9 SFO, Jun 29, 2020
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