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HV Battery Fan Comes On Anytime The Car Is In Motion

Discussion in 'Gen 3 Prius Main Forum' started by VoicesInMyHead, May 21, 2011.

  1. VoicesInMyHead

    VoicesInMyHead New Member

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    folks...

    The HV battery cooling fan (the one next to the rear passenger side door) comes on as soon as I begin to accelerate... every time. This happens even on cool days and nights. It's loud enough to hear it from my position as the driver.

    No other issues whatsoever.

    Is that normal? Granted, I don't drive it easy, but I don't drive it hard, either. I drive it like any other car I've owned... a steady acceleration up to cruising speed like all the other cars around me. I appreciate the fact it's cooling the battery, but it just seems that it's having to cool it an awful lot. What's going to happen when it really does get hot, like it does here in Georgia in the summer?
     
  2. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    ** THINKING YOU HAD A GENII **

    Did you buy it new?

    Have you ever had a pet in there? Dog? Cat? Wildebeest?

    If the fan or intake area is clogged then it will run it more often.

    The other not so good news, is that this is one of those early signs of HV Battery death as well... So it could just need a cleaning, or you might be looking at a new HV battery, or something else.
     
  3. bisco

    bisco cookie crumbler

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    what did you experience in your gen II?
     
  4. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    I thought he did have a GenII 05 and my advice was based on that. If this is your 2011, then my info is probably not relevant.
     
  5. jbpersmail

    jbpersmail Junior Member

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    why not relevant for gen III? i thought gen III doesn't have a filter either?
     
  6. 2k1Toaster

    2k1Toaster Brand New Prius Batteries

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    It would have to be one big shaggy dog for it to clog in less than a year. :)
     
  7. VoicesInMyHead

    VoicesInMyHead New Member

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    Yes, it was bought new. Only 4000 miles on it.
     
  8. bisco

    bisco cookie crumbler

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    might be a bad fan motor. break it down and have a look at it.
     
  9. direstraits71

    direstraits71 Member

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    That fan shouldn't run all the time . I assume you're under warranty. Take it to the dealer and have them fix it. That's not normal behavior.
     
  10. Flaninacupboard

    Flaninacupboard Senior Member

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    I've never even heard mine come on.
     
  11. ccdisce

    ccdisce Active Member

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    Mine is inaudible, and I live in HOT_Lanta.

    Today it is supposed to get up to 90deg F, I will check.
     
  12. adamace1

    adamace1 Senior Member

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    I have never heard mine in 42,000 miles. Maybe i will try sitting in the rear seat.
     
  13. duffasaurus

    duffasaurus Senior Member

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    There was a previous thread about this, close to the time I got my 2010 (1/10). I started to hear the fan after the first few thousand miles, not heard when stopped, but increasing with acceleration & speed. This seems to be normal and might not be heard by every driver, depending on road surface and/or interior noise! I now have 18K miles and there doesn't seem to be any adverse effects!
     
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  14. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    Depends on ambient temperatures - mine runs at low speeds quite often, and high speeds if under high charge or discharge load in higher temps. The increased capacity of the same physical pack over Gen II means the cooling system is more "aggressive".
     
  15. duffasaurus

    duffasaurus Senior Member

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    Thanks for the clarification! I'm sure concerned owners will feel better now. :)
     
  16. twittel

    twittel Senior Member

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    If you're the DIYer type, the owner's manual shows you how to remove the rear seat and take off the fan cover to check for debris. I doubt yours is clogged, but you never know. Honestly, I'd take it to the dealer if for no other reason than to get the complaint logged.
     
  17. Buderim

    Buderim Junior Member

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    Hi ,
    I have a question about HV cooling fan speeds , I live in Queensland Australia we have a similar climate to mid Florida.

    I have just got a Techstream software and have been looking at the different settings . Is there any advantage in changing the HV fan speed to give the battery more cooling ?

    If I set the fan speed to 3 would the fan speed increase with battery temp or would it just be stuck on 3 all the time ?
     
  18. BZzap!

    BZzap! Senior Member

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    If you can hear the fan running, that could be an indication that the thing is out of balance. In that case, it probably has foreign material buildup. I have never had any audible feedback coming from my fan in the 5+ years I’ve owned the car. As suggested ^^^, it may be time to inspect the fan for obstructions.
     
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  19. herqulees

    herqulees Junior Member

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    This exactly.
    The fan will always be running as long as you're moving. It speeds up with speed, accelleration, and deceleration. With the radio off I can always hear it while speeding up and slowing down as I drive, if I listen for it at least. Coming from a Gen 2 with a failed HV battery I mentioned it on the next oil change as I was a little worried. They checked the vent and said nothing was wrong the cooling is just a little more "in tune" with how you drive on the Gen 3. It's been three years now without any issue.
     
  20. Mendel Leisk

    Mendel Leisk Senior Member

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    Not exactly.

    Normally, the fan will not be running at car start-up, or for some time thereafter. The temperature of the hybrid battery pack gradually climbs, and once it crosses a threshold the fan will come on at it's lowest speed. It has a range of 5~6 speeds, and if the pack temp climbs, fan speed will go up accordingly.

    Fan status is detectable with ScanGauge (with X-Gauge programmed in), and likely various other OBD readers. I found when the car is fully warmed, driving home on a local coastal highway, cool evening and light traffic, the pack would settle in around 35C and the fan might be running speed one or two.

    At the other extreme of my experience, in heavy stop-and-go traffic, pack might be around 45C, and fan speed four. FWIW, even in those conditions, I couldn't hear it, was relying entirely on the SG reading. Maybe the sound was masked by ambient noise, and my hearing isn't the greatest.

    It's a good idea to check the fan every year or two, see if it's getting dust build-up. After a check or two, you'll have a better idea of how frequently you need to do this.
     
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