Signs/hints that your hybrid battery was on its last legs

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by rubia, Dec 28, 2025 at 7:17 PM.

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  1. rubia

    rubia Junior Member

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    Saratoga Springs, NY
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    2012 Prius
    Model:
    Four
    Just curious what peoples' personal experiences were around possible failure of the hybrid battery. What mileage, what was the car doing or not doing, etc. Interested in hearing from those of you who caught it before the red triangle of death and those of you who were, I don't know, running errands or something and then... what? Also, I think it might matter if you live in a cold climate and if that had any effect or not. TIA.

    ETA: Just to be SUPER CLEAR: I am looking for personal experiences and simple language. Did your battery fail? How, when, what were the signs ahead of time or were there no warnings you noticed as a civilian Prius driver and not an amateur mechanic or detective? What's the weather? Not guides, not step-by-step DIY anything. I know there's a lot of knowledge on this site but that is not helpful for me right now.
     
    #1 rubia, Dec 28, 2025 at 7:17 PM
    Last edited: Dec 29, 2025 at 12:20 AM
  2. PriusCamper

    PriusCamper Senior Member

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    Pacific Northwest, USA
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    2007 Prius
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    Two
    There's so many different scenarios it's hard to say without writing something really long. But basically your charge meter indicating how much battery charge you have barely changes much with a new pack and a realy old pack fluctuates rapidly from full charge to no charge and requires deep cycling to restore capacity. This is a great overview: http://www.hybridautomotive.com/frequently-asked-questions

    You can keep your pack going way longer than the Toyota Dealerships wants you to think... Cleaning the corrosion out and inspecting the pack can help prevent lots of failure points. Also deep cycling the pack every 18 months will keep it lasting way longer.

    The biggest thing people get wrong is trusting a Toyota Stealership or an auto shop that has lots of overhead, both of which will prefer to replace everything with brand new rather than taking care of what you already got to keep costs down.

    Do you or friend or family member have experience working on cars? Because that's going to be the best path forward and PriusChat folks will walk you through all the details.
     
    #2 PriusCamper, Dec 28, 2025 at 7:38 PM
  3. indel

    indel Member

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    Northwest Indiana
    Vehicle:
    2012 Prius
    Model:
    Two
    I am very interested in this topic because my battery is in a downward spiral too at 143K. I am now beginning to learn and these are the videos I have watched (or queued up) so far:

    Gregg Festo's introduction to refurbishing a hybrid battery pack with the CQ3 charger:


    Some very ingenious methods to streamline and make the charging efficient by Fix it Fox:


    A three part series on battery charging (step by step), also by Fix it Fox:




    2 years after refurbishing the battery pack, again by Fix it Fox:
     
    #3 indel, Dec 28, 2025 at 11:27 PM
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