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Why doesn't the hybrid battery fan run while when sitting still

Discussion in 'Gen 3 Prius Technical Discussion' started by Aaron Vitolins, Dec 4, 2016.

  1. Aaron Vitolins

    Aaron Vitolins Senior Member

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    It bothers me that the hybrid battery fan doesn't run when sitting still or driving very slow. I've observed this when I've done a lot of regenerative braking, and all electric driving the battery will start heating up. The fan will be running so fast I can easily hear it even with light music playing.

    I come to a stop and no noise at all! The fan just shuts off. My guess is that Toyota did this to make it The quietest experience when at a red light or what not, trying not to bother the people in the cabin.

    This is also a conspiracy theory of mine that this is why the 2010+ Prii hybrid batteries don't do nearly as well as Taxi cabs vs the older ones. My 2005 would do what ever, how ever loud it may be to cool that battery down fast as possible, even if I was just sitting. I actually enjoyed that!

    What do you wonderful people think? Let me know!
     
  2. bisco

    bisco cookie crumbler

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    i think it runs whenever the battery temp reaches the software parameters. i have never heard any of mine run. what?
     
  3. Aaron Vitolins

    Aaron Vitolins Senior Member

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    I know it does. but the fact still stands, the car can have a hot battery, but the cars software won't do anything about till you start driving. Than it proceeds to suck air in like a shop vac! It's very noticeable when that battery gets hot (to me anyway)
     
  4. bisco

    bisco cookie crumbler

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    are you using a scan gauge to measure temp?
     
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  5. Aaron Vitolins

    Aaron Vitolins Senior Member

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    It would be cool for some taxi company to hack this software and let the fan cool the battery while stopped. I bet the batteries would hold up so much better
     
  6. bisco

    bisco cookie crumbler

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    i think you can run it with a scan gauge. a lot of brilliant people have studied these cars, but i've never seen anyone recommend that the fan run more.
     
  7. Aaron Vitolins

    Aaron Vitolins Senior Member

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    Not at the moment, but I have in the past. This happened to me tonight, I didn't have it on me. But I could definitely tell what was going on for sure!
     
  8. Sam Spade

    Sam Spade Senior Member

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    I think you are making an erroneous assumption.
    I quite assure you that IF the battery really was getting too hot the fan WOULD be running while stopped.
    Maybe not as fast.
    But I think you are mis-interpreting the noise you hear and it is not (all) battery cooling fan noise.
     
  9. Aaron Vitolins

    Aaron Vitolins Senior Member

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    doesn't it seem odd though, have you read about theses 3rd gen vs 2nd gen taxis? We have a few taxi fleet owners that are members here that have been saying that the hybrid batteries on the gen 3 just don't hold up. I just had that correlation in my mind, and honestly Bisco, I think I might be on to something here
     
  10. bisco

    bisco cookie crumbler

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    well, i can't say that you aren't. :) someone would have to know the fan operating parameters on each gen. funny thing too, a lot of people say the gen 3 cells are better.
     
  11. Aaron Vitolins

    Aaron Vitolins Senior Member

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    Maybe it would in fact run all the time if it was extremely hot or at a dangerous level! But, my guess is that when it's simi hot (not really hot) it doesn't take care of its battery as good as it should, and Toyota engineers chose having a quiet cabin. And because of this, potentially more battery degration over the life of a taxi. Call me crazy! Haha
     
  12. bisco

    bisco cookie crumbler

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  13. toyotechwv

    toyotechwv Toyota Technician

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    There's also 6 different speed settings for the fan, if memory serves. Just because you don't hear it doesn't mean it isn't running.

    SM-G900V ?
     
  14. Aaron Vitolins

    Aaron Vitolins Senior Member

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    Today I put my ear to the vent, and nothing. Mind you i have very sensitive ears, and if some how it was running it would have to be running at 1. Vs being able to hear it from the driver seat even with the radio on. I know that battery was hot. I just got done driving hills, stop go, 55 mph, stop go, and some low speed ev driving
     
  15. wjtracy

    wjtracy Senior Member

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    I rarely hear our fan. Maybe only in summer on hot day.
     
  16. Mendel Leisk

    Mendel Leisk Senior Member

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    When I had ScanGauge hooked up (haven't for over a year now), with XGauges for hybrid battery temp and fan speed, I never "heard" the fan, even when the gauges indicated fan speed 4 or 5. And IIRC it was running when stopped. Stop-and-go was actually one of the worst cases, for high temps and fan speed. Ours is a 2010, fwiw.
     
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  17. Maarten28

    Maarten28 Active Member

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    I'm sorry but that is hardly a qualified judgement. I've only hear the fan come on when the ambient temperature is above 75 F. If you live in Nashville, it's cold there. I've never had the fan running with those ambient temperatures.
    Please hook up a scanguage and post temperatures before making assumptions.
     
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  18. Aaron Vitolins

    Aaron Vitolins Senior Member

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    Okay sure. My vehicle just got home from a two hour trip proceeded by city/hilly/stop and go traffic. I that point it doesn't matter what the temp is out side.
     
  19. Aaron Vitolins

    Aaron Vitolins Senior Member

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    I don't know why not? All of the the many Prii I've been in over the years I could always tell when it was running other than maybe the lowest setting. Actually in my 2005 I could hear it, and then with my long arms I could reach back from the driver seat(with it leaned back a bit) and feel the fan vent, sure enough! I do have very sensitive ears
     
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  20. Sam Spade

    Sam Spade Senior Member

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    Without a measurement you "know" nothing of the sort.

    Not only that, you don't know what is considered "hot" for that battery.

    The simple fact that the load goes WAY down when sitting still likely means that no ADDITIONAL heat will be generated in the battery and thus no additional cooling is needed either.

    But this is all wild speculation and I think you need to find something else to worry about.
     
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