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Prius won't turn on

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by twentyone21, Aug 11, 2022.

  1. twentyone21

    twentyone21 New Member

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    Miami, FL
    Vehicle:
    2010 Prius
    Model:
    IV
    Hello!

    We unfortunately left our Prius 2010 sitting for a few months while out of the country. Upon returning, we couldn't even open up the car with the key fob and no response when pressing the Power button. I jumpstarted the Prius and it came back to life - drove it 10 miles and then let it sit in Ready model for 8 hours.

    After the 8 hours, I turned it off and then immediately tried to turn it back on, but completely no response like the first time again. I repeated the process a day later (jumpstarting - 8 hours sitting), but same result.

    After each jumpstart the warning message (Key Not Detected) is being displayed continually while the car is on, even with the fob right there. I've ordered a new fob battery and a multimeter to check the 12 V.

    Trying to get an idea of what the issue could be before taking a costly trip to the mechanics. Hoping it's just the 12V battery that needs replacing and not something more serious.

    Thank you so much for any replies!

    Ryan
     
    #1 twentyone21, Aug 11, 2022
  2. PriusCamper

    PriusCamper Senior Member

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    The charge the 12v gets when car is left on for 8 hours is fairly weak sauce... You need a legit battery charger that's a smart charger that can pump in 8amps and left charging overnight if you want your battery to fully recover. Here's a respectable charger that doesn't cost much: https://www.ebay.com/itm/354203591176

    I wouldn't be too concerned about your FOB issues until you have a fully charged battery.
     
    #2 PriusCamper, Aug 11, 2022
  3. tankyuong

    tankyuong Senior Member

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    dead battery
     
    #3 tankyuong, Aug 11, 2022
  4. Mr. F

    Mr. F Active Member

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    Vehicle:
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    Some auto parts stores (such as AutoZone) offer free 12V battery charging. I don't know if they put the battery through a repair mode, though. Even if you have to buy a charger and do it yourself, reviving it will cost much less than springing for a new one.
     
    #4 Mr. F, Aug 11, 2022
  5. bisco

    bisco cookie crumbler

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    it's probably the 12v, how old is it? killing it dead often renders it impossible to bring back
     
    #5 bisco, Aug 11, 2022
  6. twentyone21

    twentyone21 New Member

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    Vehicle:
    2010 Prius
    Model:
    IV
    Thank you everyone. I bought the Yonhan battery charger online, and have two questions:

    1. Do I need to jumpstart the car and have it in Ready mode before I hook up the battery charger? I tried hooking it up while completely dead and the battery charger display told me the temperature and voltage, but didn't seem to be actively charging. I plan to put it in Repair mode for the first four hours and then charge.

    2. Do I connect the negative clamp to the negative terminal of the Prius battery? The charger manual and sites online seem to say so, but other people say the negative clamp of the charger needs to be connected to a grounded spot on the frame, like we do during a normal jumpstart.

    Thank you
     
    #6 twentyone21, Aug 15, 2022
  7. bisco

    bisco cookie crumbler

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    just hook it up to the battery with the car off. if the battery is really old/bad, it will not be able to recharge/restore it
     
    #7 bisco, Aug 15, 2022
  8. PriusCamper

    PriusCamper Senior Member

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    Hook the charger up directly to the battery before you plug it in. Then look at the screen of the charger. There should be enough power in your 12v to power up the screen and tell you what your current voltage is. Let us know what that voltage number is? Then plug in the charger and it will take car of everything else for you automatically. When the screen finally says 100% your battery is fully charged.
     
    #8 PriusCamper, Aug 15, 2022
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