2007 Prius. Hybrid battery (original) failing...

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Danica, Aug 6, 2025 at 7:04 PM.

  1. Danica

    Danica New Member

    Joined:
    Oct 10, 2024
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    Location:
    California
    Vehicle:
    2007 Prius
    Model:
    ----USA----
    I was driving home from some errands this morning, almost home with perishable groceries in the car, hot day, AC blasting -- and the car starts going crazy on me. AC stops working, the car is beeping, brake light coming on, and the red triangle. Then the car literally would not go.

    Because of the heat and the groceries I just wanted to get home, which I somehow managed to do by turning the car off and on again a bunch of times. Each time the car would go maybe a couple of hundred feet before failing again. Once I got home, I had the car towed to a local mechanic, who just called me with the news.

    He said their diagnostic tool registered a large power drop-off, and since the regular battery is fine, it must be because the hybrid battery is going bad.

    I know this is a long shot, but I don't suppose there is any other possible explanation for the power drop-off?

    At any rate, I'm at a loss as to what I should do next. One mechanic told me that nobody in my area (Coachella Valley) has the ability to replace a hybrid battery. He said I would need to have the car towed to a neighboring county, and then the new battery would cost me at least 5K. I see cheaper prices on the internet, but have no idea if any of them are trustworthy.

    At that price, am I just better off getting a new (used) car? My Prius seems to be in good shape otherwise, in spite of being old.

    How do I even find somebody who can reliably replace the battery? Just call every mechanic in the area until I (hopefully) find somebody?

    Any suggestions or advice would be greatly appreciated. Thank you.
     
    #1 Danica, Aug 6, 2025 at 7:04 PM
  2. Hayslayer

    Hayslayer Member

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    Location:
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    Vehicle:
    2009 Prius
    Model:
    Touring
    It sounds like they didn't actually read the codes supplied by the car. They're guessing. You need to find someone who can actually read hybrid codes. THAT is your number one priority.

    Sounds to me like possible your inverter cooling water pump failed. This causes the inverter electronics to overheat and the car will protect itself by killing the AC and power to the transaxle. Pull over, turn it off, let it sit for a few minutes, it cools and allows you to drive again, for a short bit, then heats up again.

    Go pick up the car, but leave the AC off and stay under 35mph. This usually allows you to drive many miles before it gets hot. See if it works.

    I didn't see the part where you mentioned the brake light being on. Probably not the ICWP. BUT, you still need actual codes, not guesswork.
     
    #2 Hayslayer, Aug 6, 2025 at 11:24 PM
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  3. JC91006

    JC91006 Senior Member

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    Location:
    Los Angeles, CA
    Vehicle:
    2008 Prius
    Model:
    II
    The 2nd generation prius is very reliable. But there are 2 failures that are pretty much guaranteed. The brake actuator/accumulator pump and the HV battery. Seems you hit one of the failures and the brake failure won't be too far behind. Both of these are high ticket items. So if you decide to fix the battery (let's say the current price is $2500 for a new one), prepare yourself for another $2500 for the brake actuator that will follow. If you're not willing to spend that type of money, best you just sell the car now.

    I use to help install these batteries and brake actuators, but I've since taught a nice apprentice to do this work. If you would like someone to go to you and install these items (you purchase them through the dealership), he can do it at a very low price, compared to a shop.
     
    #3 JC91006, Aug 6, 2025 at 11:25 PM
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  4. Tombukt2

    Tombukt2 Senior Member

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    Location:
    Durham NC
    Vehicle:
    2009 Prius
    Model:
    Base
    My friends lil daughter could change the hybrid battery with a piece of plywood avail on side o road in lots places but yeah it's like 87 pounds. When you starting stopping going 50 feet . Did maybe try n turn power rubbing devices off possibly it's a long shot I know . But it's a thing . Yeah and o7 w original being tested on the heat will bring it down quickly . And make it time.
     
    #4 Tombukt2, Aug 7, 2025 at 6:24 AM
  5. Tombukt2

    Tombukt2 Senior Member

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    Location:
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    Vehicle:
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    Base
    So before 3K on a real battery . Is really time to think is this model really needed her or? 3K can put you in a nice Yaris that requires none these antics . Near similar mpg . Seriously.
     
    #5 Tombukt2, Aug 7, 2025 at 6:27 AM
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