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Should the Battery Fan come on during normal driving?

Discussion in 'Gen 2 Prius Main Forum' started by uart, Jan 22, 2010.

  1. uart

    uart Senior Member

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    Today was pretty hot (about 38C/100F) and after a short drive I noticed the battery fan was running in the back. This is the first time I've actually noticed it running but I'm thinking it probably happens more often and I just don't normally hear it (because in hot whether I always have the A/C or cabin fan running which masks the sound).

    So I'm just wondering how many others have had the battery fan come on and how frequent is this for others.

    One other thing. I've got the "EV" button but when I try to use it I often get the error, "EV mode is currently invalid" or something like that on the MDF. In the past I've searched all the possible reasons for EV denial and none seemed to make sense, but now I'm thinking that they must have been due to battery over-temperature. What do you think?
     
    #1 uart, Jan 22, 2010
  2. Rokeby

    Rokeby Member

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    uart,

    Posters have reported hearing the HV battery fan running shortly after
    startup after parking their car in the full nooday sun on a hot day. The
    temps inside the car can be > 130 degF (C?), and although it takes a
    while, in time the heat penetrates the hatch floor and heats up the HV
    battery. (Often called a "hot soak." There is a "cold soak" too, but I doubt
    you'll ever see it. :p )

    Yes, one of the EV mode denial conditions is overly high HV battery temps.
    This has occured in my car at HV battery temps before the fan has come on.
     
    #2 Rokeby, Jan 22, 2010
  3. uart

    uart Senior Member

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    Thanks for the info Rokeby. Yeah it would have been over 100F here earlier today so I guess it was just "heat soak" as you say. Also, although the drive was short (about 3 miles) it was mostly up hill so the electric motor was probably putting in some assistance there as well.
     
    #3 uart, Jan 22, 2010
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