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Odd startup behavior... dead 12v battery?

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by danep, Jul 23, 2015.

  1. danep

    danep Junior Member

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    Yesterday evening I went to start my 6 year old gen3, and got absolutely no response- no green ready light, and none of the usual whirs and hums. I figured a light was left on and the battery was dead. I went inside my house to get my multimeter and when I got back to the car- wouldn't you know it started right up! I then verified that there were no lights on, so I'm not sure what would have drained it.

    This evening the exact same thing happened again. I was able to verify that while the car was dead the battery showed only 6v, but after a few minutes it shot up to 12v and the car was able to start.

    I've never replaced the 12v battery so I'm pretty sure that's the problem... but why would the battery resurrect itself after a few minutes of waiting? Can the traction battery trickle charge it or something?
     
    #1 danep, Jul 23, 2015
  2. bisco

    bisco cookie crumbler

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    sounds like a short inside the battery. or if you checked it at the front jump points, a bad ground connection.
     
    #2 bisco, Jul 23, 2015
  3. Mendel Leisk

    Mendel Leisk Senior Member

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    6 years is a long time too. Maybe time?
     
    #3 Mendel Leisk, Jul 23, 2015
  4. CR94

    CR94 Senior Member

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    Right, or possibly an iffy intermittent connection on the positive terminal.
     
    #4 CR94, Jul 23, 2015
  5. girluvr

    girluvr Junior Member

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    I would first recommend you do some routine battery maintenance, which would involve all the steps as if you were replacing the 12 volt far rear battery using a wire brush terminal cleaner on all connections. Inspect everything, use a. Solution of baking soda and water to wipe everything clean. If you have a meter, test the voltage of the battery etc.
    This should all help you decide if your battery needs replacement or not.
    It's amazing anything with a battery goes for 6 years with no maintenance needed.
    I would price a yellow top Optima brand battery specific to your Prius model from. $100 to $150 us dollars for when the battery fails to start the car.

    SM-P900 ?
     
    #5 girluvr, Jul 24, 2015
  6. JimN

    JimN Let the games begin!

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    Three times is a charm. When the computers wouldn't boot up on the first attempt, they did on the third.
     
    #6 JimN, Jul 24, 2015
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