2004 Prius w/ 170k miles, weak 12v & P0A80

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by PriusOwner2017, May 10, 2018.

  1. PriusOwner2017

    PriusOwner2017 New Member

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    Hi!

    I love my 2004 Prius w/ 170k miles, but recently my dashboard lit up with Red Triangle, Check Engine, VSC, and (!) lights. The Prius is driving the exact same way it always does, no change in performance or gas mileage.

    I took the car to the mechanic and of course I get the P0A80 code to replace the hybrid battery. I asked him to clear the codes. The car was doing good but when I refueled the warning lights came back on.

    Last summer I had the EXACT same combination of lights come on. I had the mechanic clear the codes. The lights disappeared and never came back on and my Prius drove for thousands of miles over 9 months without an issue, 45mpg average.

    I went in to diagnostic mode to check the 12v battery and it actually looks pretty weak. Here's what I got-
    11.4v in standby mode
    10.5v with the lights on in standby
    13.9v with engine fully on
    This 12v battery is the same one that was in the car when I bought it 2.5 years ago.

    Is there any way the weak 12v is triggering the warning lights/P0A80 code?
    Or is the weak HV battery causing low readings from the 12v?
    I'm ready to bite the bullet and buy the $1000+ refurbished battery if I absolutely have to.
    However, this problem fixed itself in the past. And if I could take care of this by simply replacing the 12v my wallet would surely appreciate that.

    Thoughts?
     
    #1 PriusOwner2017, May 10, 2018
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Replace the 12V battery now.

    A waste of money to buy the $1K remanufactured battery; plan to buy a new battery at $3K or make a plan to replace the car.
     
    #2 Patrick Wong, May 11, 2018
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  3. ericbecky

    ericbecky Hybrid Battery Hero

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    Yep. Get a new 12v. Yours is too low.

    Report back and let us know the result.

    Would be helpful if the mechanic cold tell what the voltage of the hybrid battery blocks were/are.

    ForFaround $75 you could even buy some simple tools to see this data yourself.
    - Android phone/tablet
    - elm 327 Bluetooth OBDII reader
    - Torque Pro app
    With this you could see 12v battery voltage, read and clear error codes, hybrid battery info.
     
    #3 ericbecky, May 11, 2018
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  4. PriusOwner2017

    PriusOwner2017 New Member

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    I took the Prius to Pep Boys to find out if I needed a new 12v. They told me the problem was the HV battery although I'm not positive they actually tested the battery and didn't just read the error code.

    The car was struggling to reach high speeds as I was driving it to the Pep Boys.

    Should I get a second opinion? should I just replace the battery and cross my fingers that it fixes the problem?

    Why is it not worth it to get a refurbished battery? The one I'm looking at comes with a 3 year warranty. I'll probably resell the car within a year anyway.
     
    #4 PriusOwner2017, May 15, 2018
    Last edited: May 15, 2018
  5. ericbecky

    ericbecky Hybrid Battery Hero

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    Sure sounds like a hybrid Battery problem.

    A used (refurbished) battery it will not last as long as a new one.

    Will you be doing install yourself? Of so, then labor is free, and it won't be as financialy painful if/when you need to swap out the used for another used one under warranty.
     
    #5 ericbecky, May 15, 2018
  6. PriusOwner2017

    PriusOwner2017 New Member

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    Update- I took the car to my trusted neighborhood mechanic who tested the 12V battery and told me that YES, it was dying and needed replacing. He's installing an Optima Yellowtop this afternoon.

    Fingers crossed that the dashboard doesn't light up again. If so, I guess we know what that means! *gulp*
     
    #6 PriusOwner2017, May 15, 2018
  7. ericbecky

    ericbecky Hybrid Battery Hero

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    It still may be worth your while to purchase the $75 in diagnostic tools.

    Will save you running around town guessing what is wrong.
     
    #7 ericbecky, May 15, 2018
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  8. PriusOwner2017

    PriusOwner2017 New Member

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    UPDATE - So I got the 12v replaced and it did not fix the problem. I'm telling myself that it was going to go soon anyway so I don't feel like I wasted ~$300 to replace it. Heh heh...

    What DID fix the problem was (you guessed it) replacing the hybrid battery with a refurbished one courtesy of Hybrid Restoration in Memphis. I took the car out for a spin today and its doing great. I will report back if any issues arise. If you don't hear from me for a while its because the issue is resolved!
     
    #8 PriusOwner2017, May 17, 2018
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  9. fotomoto

    fotomoto Senior Member

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    Yeah, you needed a new 12v anyways and it will most likely outlast the (new) used HV battery. o_O It sounds weird to say but let's hope that the refurb dies before the warranty does and Hybrid Restoration is good on their word and work! (y)

    Keep us updated.
     
    #9 fotomoto, May 17, 2018
  10. ericbecky

    ericbecky Hybrid Battery Hero

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    Priusowner,
    Do you have diagnostic tools so you could show us the data from the battery?
    Something that shows the voltage of the highest and lowest hv battery blocks?
    Would be interesting to see how healthy the restored hybrid battery looks.
     
    #10 ericbecky, May 17, 2018
  11. PriusOwner2017

    PriusOwner2017 New Member

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    Sorry, Eric, wish I could help but I don't have any equipment to test the voltage on the blocks.
    Drove the car around all day today. Its doing beautifully!
    Most likely I'm going to sell this car within the next 12 months so hopefully I won't have to deal with this again :)
     
    #11 PriusOwner2017, May 17, 2018
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