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Replace 12V battery or something else

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by MX5Kimo, Dec 1, 2023.

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  1. MX5Kimo

    MX5Kimo Junior Member

    Joined:
    Aug 29, 2022
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    Location:
    Sacramento
    Vehicle:
    2011 Prius
    Model:
    Three
    I have a 2011 Prius with the original 12V battery. 180,000 miles.

    it was working fine until last week. All sorts of failure to start issues. Voltmeter said it had 7.5V. I charged the battery back up to 11.88V, dropped in the car and car still would not start. I attached portable battery jump starter. Engine started. Ran fine.

    Next day, problem starting until made sure all lights and accessories were off. Then started after some encouragement. Measured at 12.8V.

    measured at 12.8V a couple days later. Tried to start the car. Car partially started where tried to start but could not start. Could not turn off car also unless I pulled the battery. When car was in the partial start state, I measured 7.5V. When I unplugged the battery, it measured 12.8V.

    I assume it is a dead or dying battery. I have one on order. But could this be something else?
     
    #1 MX5Kimo, Dec 1, 2023
  2. JC91006

    JC91006 Senior Member

    Joined:
    Nov 10, 2013
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    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    you should try changing the battery and decide if it's something else. 13 years is a great run for any 12v battery, might be the longest running 12v ever
     
    #2 JC91006, Dec 2, 2023
    Brian1954 likes this.
  3. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
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    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    How are you measuring 12.8 volts?
     
    #3 bisco, Dec 2, 2023
  4. Jdh2425

    Jdh2425 Junior Member

    Joined:
    Apr 1, 2019
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    Location:
    Baltimore
    Vehicle:
    2010 Prius
    Model:
    ----USA----
    My 2010 with 242,000 miles still has both original batteries. I know the day is soon coming when one or the other will start giving problems. So far both are doing OK. Unless something else comes up, I plan on changing them when necessary - cheaper than a new car!
     
    #4 Jdh2425, Dec 2, 2023
    CR94 likes this.
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