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Is Battery Temp Reason for Low MPG @ Lo Temp?

Discussion in 'Gen 2 Prius Technical Discussion' started by msilverb, Feb 19, 2008.

  1. msilverb

    msilverb New Member

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    I wonder whether low temperature short trip MPG could be improved if a system was included to raise the battery temperature before driving. One possibility is an AC plug in connection and a timer to turn it on sufficiently early in the morning.
     
    #1 msilverb, Feb 19, 2008
  2. efusco

    efusco Moderator Emeritus
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    It's certainly a factor, but there are multiple factors in the cold on short trips. The battery takes a very long time to warm up and when it's really cold the HV capacity is reduced and does impact FE.
     
    #2 efusco, Feb 19, 2008
  3. diamondlarry

    diamondlarry EPA MPG #'s killer

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    It seems that any temp below 25F for sustained periods will cause EV mode to not be available. It also seems to cause the ICE to come on if you even think about touching the gas pedal.
     
    #3 diamondlarry, Feb 19, 2008
  4. efusco

    efusco Moderator Emeritus
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    Hmmm, that's not my experience....unless you mean the battery temp specifically. But as long as the battery and ICE are warm I can EV, glide, etc. almost like in warm weather no matter the outside temp.
     
    #4 efusco, Feb 19, 2008
  5. jayman

    jayman Senior Member

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    In very cold weather, you will experience improved heater performance and fuel economy by using the EBH and by blocking the front grille
     
    #5 jayman, Feb 19, 2008
  6. diamondlarry

    diamondlarry EPA MPG #'s killer

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    Sorry. Yeah, I was talking about battery temp. When my car is in the garage overnight with the EBH plugged in, I have full use of EV mode whenever I want it. When I'm parked at work and the car gets an 8 hour cold-soak, I quite often never get EV mode even after over 15 miles. I do however, get to glide once the coolant reaches 155F no matter how long the car has been in the cold.
     
    #6 diamondlarry, Feb 19, 2008
  7. msilverb

    msilverb New Member

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    The comments don't relate directly to my question. I live in CT and during the winter mostly make short trips. When the temperature is 32F and below I average less than 38 MPG. When it is about 38 and above I average 43 MPG or higher. This seems too big a change to be the result of the control system warming up the catalytic converter. It would be easy to pre-heat the battery with a thermostatically controlled heater while it is in my garage. Do you guys think this would help? Another question is does an EBH raise the battery temperature?
     
    #7 msilverb, Feb 21, 2008
  8. jayman

    jayman Senior Member

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    No, the EBH does not affect battery temp

    I would think it easier to heat the garage itself than just the battery pack. I used to have a condo with heated underground parking, now I have a 1,348 sq ft home with heated attached garage.

    It's a Reznor gas heater in the garage. Appears to add about $45 to the gas bill in bitter cold temps, with the heater set at +50 F. Very nice to hop in a car without scraping frost off, just drive off
     
    #8 jayman, Feb 21, 2008
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