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2012 Prius struggling during first 10 minutes during high heat

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by PbRius2012, Jul 18, 2024 at 6:56 PM.

  1. PbRius2012

    PbRius2012 New Member

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    Vehicle:
    2012 Prius
    Model:
    Two
    First post, I am not nearly as knowledgeable as you all, so I’m hoping that you can give me some insight based on what I’m describing. Also, I’m not looking for a lot of DIY work, as I don’t have the skills or time to take that on. I’m trying to see if what I’m describing can be fixed by a mechanic and if it’s worth it.

    2012 Prius, original owner, 213k miles. Mostly highway for the first 180 or so, then more city type driving since then. This summer, on really hot days (85 degreees F and higher), the car is really struggling for about the first 10 minutes of driving. The battery meter stays around 2 or 3 bars, and the engine is running the entire time. During acceleration, it seems like it’s getting zero help from the electric motor. The engine also seems like it’s staying at a high rev rate for a few more seconds when I take my foot off the gas. I keep the AC blasting, and I know that’s a big draw from the battery, but I’ve always done that on hot days. MPGs are around 32 during this time period, about 10 lower than normal during the less hot months.

    The symptoms seem similar to what this person had, but my car is much older and has far more miles: 2013 Prius struggling in heat | PriusChat

    Any ideas would be greatly appreciated!
     
    #1 PbRius2012, Jul 18, 2024 at 6:56 PM
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    Vehicle:
    2010 Prius
    Model:
    Touring
    You could try Dr Prius (phone app). It requires an OBD Bluetooth dongle; Carista worked well for me, with an iPhone. Simple assessment looks like attached.
     

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    #2 Mendel Leisk, Jul 19, 2024 at 7:34 AM
    BiomedO1 and Brian1954 like this.
  3. ASRDogman

    ASRDogman Senior Member

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    Too many factors to give any real diagnoises....
    It does seem like your hybrid battery is weak. Is it original?
    It seems this issue began when you stayed in the city. The hybrid battery
    does take longer to charge up with city driving.

    Have you had the egr system cleaned? Changed the air filter?

    Since you don't want to do any work on it, you need to seem a good shop that
    is familiar with the Prius and get a diagnoised performed.
    Mostly what you'll get here is "guesses" as to what it could be. And it will only
    fustrate you.

    Since you don't want to do any work on it, you need to find a good shop that
    is familiar with the Prius and get a diagnoised performed.

     
    #3 ASRDogman, Jul 19, 2024 at 8:46 AM
  4. BiomedO1

    BiomedO1 Senior Member

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    Yep, sounds like a weak traction battery. If the cooling fans in the traction battery pack has never been cleaned out - now probably a good time to do that and make sure it's operating correctly. It's probably too late but it sounds like a couple of weak cells in your traction pack. Your entire pack recharges back up in about 10 minutes, then your symptoms goes away. Once you park the car overnight the cycle repeats. If you don't blast your AC, the draw on your pack is lessen and you problem will probably go away for now.

    Hope this helps....
     
    #4 BiomedO1, Jul 19, 2024 at 11:21 AM
  5. PbRius2012

    PbRius2012 New Member

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    Location:
    New York
    Vehicle:
    2012 Prius
    Model:
    Two
    The weird thing here is that it’s only happened this year, it’s only for the first 10 minutes or so, and only if the temp is 85-90+. Regardless, I got a reader and the Dr. Prius app. I ran the two diagnostics and they both were fine (battery pack registered 61% which was “fair”, and I guess fine for a 12 year old car). If anyone sees anything in these screenshots that is alarming, please let me know!

    For now though, I’m probably just going to drive it as is and just deal with those extra hot days as they come. I may attempt the battery fan cleaning, the Prius service center charges 180 for that and that looks like it’s worth taking the time to save the dime.
     

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    #5 PbRius2012, Jul 22, 2024 at 12:42 PM
  6. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Vehicle:
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    Model:
    Two
    Air conditioning often works harder (draws more power) in the first few minutes, assuming the car is parked outside in sunlight.

    Try a trip without A/C.

    My guess (and it really is a guess without direct diagnostics) is that your A/C load vs. a hot cabin is enough to make a "fair" battery act like a "poor" battery.

    After those first few minutes, the A/C energy demand slacks off, and there is more available for other duties.
     
    #6 Leadfoot J. McCoalroller, Jul 22, 2024 at 6:17 PM
  7. ChapmanF

    ChapmanF Senior Member

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    Vehicle:
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    Model:
    IV
    If I watch the "A/C watts" PID on my ScanGauge while driving, I see the car often drops the compressor power to zero when I ask for any more than modest acceleration.

    Some old mopars and the like would have a "WOT Cutout" in the A/C clutch circuit, for the same reason.

    So I'd like to think it isn't the A/C sapping too much power when you're actually trying to accelerate....
     
    #7 ChapmanF, Jul 22, 2024 at 6:44 PM
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