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How often does your Hybrid Battery Pack FAN turn on?

Discussion in 'Gen 3 Prius Technical Discussion' started by silentak1, Jun 21, 2010.

  1. silentak1

    silentak1 Since 2005

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    It seems like the fan that cools the hybrid battery pack turns on quite often, almost everyday after two or three hours of driving. I heard it once or twice on my '05, but on this one I hear it pretty much everyday.

    Normal driving, temps 50-80s, AC always on at 72-76. Not pulling loads or carrying people, just normal driving. Turns on regardless of driving conditions and outside weather.

    Anyone else with me? I'm assuming it's normal.
     
  2. GrumpyCabbie

    GrumpyCabbie Senior Member

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    Is the battery fan loud? I only ask because I don't think I have ever heard it. Even when we've had 30c weather (hot for here) and the a/c hummed like crazy, I don't think the battery fan has been loud.

    Is it supposed to be loud? Does it really strongly blow air out the vent in the back seat or is it more a gentle breeze?
     
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  3. silentak1

    silentak1 Since 2005

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    It's not very loud, but you can hear it if you have the audio off. It's more like a gentle to medium fan speed and it only sucks in air from the cabin into the battery pack.
     
  4. JimN

    JimN Let the games begin!

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    I don't think it ever turned on--2006 & 2010.
     
  5. adamace1

    adamace1 Senior Member

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    I have never noticed mine. But i don't have the best hearing, so if the fan is not loud i might not hear it. But i can hear a dvd drive across the room.
     
  6. Felt

    Felt Senior Member

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    I have no knowledge that mine has ever come on. Once while driving down the mountain and the HSI screen displayed a full HV battery, I suspected that heat might be building and need to be dissapated, and asked someone sitting in the right rear if they could detect a fan. The reply was no.

    I will be more attentive from now on and listen for something.
     
  7. cycle11111

    cycle11111 New Member

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    I live in Texas and do a lot of solo commuting and can't say I have ever heard it. It was 97F today - nice and toasty and got 60mpg to work and 67mpg going home. My spouse can pretty much get 40-44mpg in any conditions good or bad - oh well
     
  8. silentak1

    silentak1 Since 2005

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    Interesting, so maybe after all it's not so normal.
     
  9. Scaurex

    Scaurex Junior Member

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    Yes, I hear it after about 20 minutes of city driving followed with 10 minutes of highway driving. It comes from the passenger side, rear seat grill/vent. Sounds like road or wind noise at first, if you slow down or stop, then you can tell it's a fan. Runs about every 5-7 minutes or so of sustained 110KPH driving (about 68mph) with the AC on. Seems the fan is a variable speed, depending on load and temperature. Traction battery was 2 bars from the top.
    If your AC is on recirculate, the fan seems to run more often. If you take the AC off recirculate, the air gets pushed through the vent, cools the battery and exhausted out of the car. So the fan runs less, or not at all when the AC is set to fresh air.
     
  10. seasalsa

    seasalsa Active Member

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    Never heard it in 5 years in the GII and haven't heard it yet in the GIII. the real answer is "When it is needed".
     
  11. silentak1

    silentak1 Since 2005

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    That's pretty much part of my scenario... precisely described. I do run the AC always on re-circulate rather than fresh-outside-air. Will give it a try with fresh-outside air but what you're saying makes sense. Thanks.
     
  12. ken1784

    ken1784 SuperMID designer

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    Please be aware it is true only on the Gen2 Prius.
    On the Gen3, the exhaust remains in the luggage part.
    Therefore, there is no difference between recirculate and fresh setting.

    Ken@Japan
     
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  13. Tideland Prius

    Tideland Prius Moderator of the North
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    I've never heard it in the Gen 2 even in 30°C weather... then again, the A/C blowing at full speed may have masked the sound. Can't say I've heard it in the Gen 3 either (but only have driven in 30°C weather a few times and they were under light load)
     
  14. chartquist

    chartquist New Member

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    Here in Memphis, I hear the fan almost every day and I have to say it is somewhat buzzy and annoying. It's about the same noise level as 1/3 to 1/2 fan speed on the dash vents, which is pretty loud to me compared to other cars. I never heard the battery fan even once on my 2004 Gen II that I traded in last Fall for the Gen III.
     
  15. Felt

    Felt Senior Member

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    I think the question is interesting, and I have learned from the responses .... but I really am not concerned, and I doubt the question was written as a concern.

    I consider the "transparency" (that is Obama talk) of the HV fan to be one of the remarkable features of the G3 .... that the vehicle has been engineered to take care of these important details with no action on my part. Neither am I concerned about the A/C compressor running while at a stop light, or the brakes recharging the battery, or for that matter, how often the ICE starts to keep the HV battery between 40% and 80%. It is just a remarkable and well engineered vehicle. Thanks Toyota.
     
  16. pakitt

    pakitt Senior Member

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    After 12.000 km I still never heard it...
     
  17. GrumpyCabbie

    GrumpyCabbie Senior Member

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    I think heard it for a few seconds the other day.

    Was vacuuming the car today and gave the vent a quick once over with the soft brush attachment. The sun was shining into the vent and when I looked inside I found that there appears to be a membrane or a filter or mesh or something.

    Is this normal or has something been disturbed when my two way radio aerial was fitted? I'd have thought a filter would impede the airflow, though obviously would filter any fluff out.
     
  18. DetPrius

    DetPrius Active Member

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    14,000+ miles on my 2010 and I've never heard it.
     
  19. Scaurex

    Scaurex Junior Member

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    If you always have the radio on/window down/sunroof open/ or are driving in the rain, you can't distinguish the fan noise from these sounds. Smooth road or highway, with no radio, it's easy to hear.
     
  20. jsmithy

    jsmithy Hypermiler and Freedom Lover

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    Will this fan run after the car has sat in the garage all day without being driven? Yesterday I heard a fan running in the rear of the car from the outside after the car had sat for about 10 hours in the garage. It was about 80 degrees yesterday with low humidity, so it was not hot in the garage.