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Auxiliary Battery advice

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Mark746, Jul 8, 2015.

  1. Mark746

    Mark746 New Member

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    Hello all!
    New owner of a used 2007 Prius. As I've never owned a hybrid, I've been reading everything I can and heading off paranoia at the pass. Recently, after a week or so of slow starts with the red exclamation showing briefly at boot, my car died completely when someone left a door slightly ajar. I got it jumped and let the car sit in ready mode for an hour and a half. The minute it happened, I ordered a yellow top to install figuring my aux battery was on the decline. But, since the jump (3 days) every time I enter diagnostic to test the battery it's around 12 volts. The car starts immediately. Did I jump the gun? Should I return the yellow top? Or was the fact it was diminished in the first place a sign it should be replaced? Help.

    Thank you.

    Mark
     
    #1 Mark746, Jul 8, 2015
  2. Barnstormer!

    Barnstormer! Junior Member

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    12v is too low, you'd be well served to replace the battery. It was the first thing I did when I got my 2006 (similar glitchy moments at startup) and it fixed it 100% for me. From reading around here, it's pretty common. 12.4-12.8 is what you'd like.
    FWIW, the 12v battery doesn't actually spin the engine for start, so a weak battery doesn't show itself in the same way it would in a "normal" gas engine car.
     
    #2 Barnstormer!, Jul 8, 2015
    Last edited: Jul 8, 2015
    bisco likes this.
  3. bisco

    bisco cookie crumbler

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    new battery should read 13+ with a full charge. make sure you check/charge the yellow top before installing.
     
    #3 bisco, Jul 8, 2015
  4. kenoarto

    kenoarto Senior Member

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    Unlike non-hybrid cars, it takes 8 hours for the 12v battery to charge while the car is parked. Or get a battery charger.
     
    #4 kenoarto, Jul 8, 2015
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