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12 Volt Battery Question

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by gt5-33, Mar 8, 2011.

  1. gt5-33

    gt5-33 New Member

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    I have a 2005 Prius with 39K miles which I purchased used. Not sure if the 12 volt battery has ever been replaced. I was sitting in the car this AM waiting for work listening to the radio. All of a sudden the radio started cutting in and out. I turned off the radio and tried to start the car but the dash just started flashing and I could not select drive. Sounds like the 12 volt battery is bad but I'm not sure why the dash is flashing the trouble lights, the fuel gauge is flashing and the transmission gear selection display is flashing. Would this be normal when the 12 volt battery is bad. Thanks
     
    #1 gt5-33, Mar 8, 2011
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, you need a new 12V battery. When the battery voltage is low, that can cause weird electronics behavior.
     
    #2 Patrick Wong, Mar 8, 2011
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  3. seilerts

    seilerts Battery Curmudgeon

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    Yes, replace your 12V, or at least put it on a charger at 4 amps or less to see if it will hold a charge. You may or may not be aware that it is an AGM battery in the back of the car, and the only drop in replacement is from the dealer. A popular aftermarket option is an Optima Yellowtop, but you need to change the terminals. If you spend a lot of time with the car off listening to the radio, you should consider this modification. A place out of California sells the battery and kit for $180, see Toyota Prius 12 Volt Auxiliary Battery with install kit for 2004 - 10
     
    #3 seilerts, Mar 8, 2011
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  4. KK6PD

    KK6PD _ . _ . / _ _ . _

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    #4 KK6PD, Mar 8, 2011
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  5. gt5-33

    gt5-33 New Member

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    Thanks to all who replied. Got the car jumped started and drove home. Order the Optima plus kit for the 180.00. Local dealer wanted 174.70 plus sales tax.
     
    #5 gt5-33, Mar 8, 2011
  6. okiebutnotfrommuskogee

    okiebutnotfrommuskogee Senior Member

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    I put an Optima in my 07. Installation is easy, just read and follow their very clear instructions. I did use a small 12 volt battery to keep the car "alive" during the swap. That way you don't loose any of your settings and there will be no sparks when you make your final negative connection.

    If you have any questions, pm me and we can talk about it.
     
    #6 okiebutnotfrommuskogee, Mar 8, 2011
  7. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Since the OP has reported "flashing...trouble lights" I suggest that when the OP installs the new 12V battery, that he allow all ECUs to power down by not using a "keep alive" battery. Then when the new 12V battery is connected, all ECUs can restart without having any "noise" in memory resulting from low 12V power.
     
    #7 Patrick Wong, Mar 8, 2011
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  8. okiebutnotfrommuskogee

    okiebutnotfrommuskogee Senior Member

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    That's a good suggestion, Patrick. Sorry, I missed that detail from the OP.
     
    #8 okiebutnotfrommuskogee, Mar 8, 2011
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