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Plug in heater vs. using heater

Discussion in 'Gen 2 Prius Technical Discussion' started by DjEZ, Nov 21, 2007.

  1. DjEZ

    DjEZ Junior Member

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    Will buying a cigarette lighter car heater be more economic in term of millage than having the car running the engine for heat?
    What is the effect on the battery, what i know is that the cigarette outlets run from the 12 V battery (will this affect the High Voltage Batt)
    I observed while stopped the engine will stop running if i turn off the AC/Auto or the Windshield defogger.

    Thanks for any reply
     
    #1 DjEZ, Nov 21, 2007
  2. efusco

    efusco Moderator Emeritus
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    Definately would not be as efficient as just using the built in heater which uses excess ICE heat.

    If you want to be as efficient as possible then bundle up to keep warm and leave the heat set to "Max cool" and the fan on the lowest setting (ie manual..no auto, no A/C) for the first 10 minutes or so of driving..then turn the temp up to around 68...that should be more than comfortable enough with your warm clothing and should put littl drain on the fuel economy.

    Also, seriously consider an engine block heater...it will start you out with better fuel economy and you'll get your engine up to optimal operating temp much more quickly and thus you'll have heat in the cabin more quickly.
     
    #2 efusco, Nov 21, 2007
  3. bwilson4web

    bwilson4web BMW i3 and Model 3

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    These are rough 'order of magnitude' numbers but the plug-in, space heater is not a good approach.

    For every 92 watts of electric heat, you need ~100 watts of power from the inverter generating the 12VDC power. To generate the 100 watts of power for the inverter, the engine has to burn at least 300 watts of gasoline heat. Of the 200 watts lost, ~100 watts goes out the tail pipe and ~100 watts goes into the engine coolant. The engine coolant, otherwise waste heat, is what the vehicle heater uses to heat the cabin. Electric heat is fast but it has to be replaced by burning fuel and reusing the heat lost from normal ICE operation is very cost-effective.

    With Christmas coming up, 'electric socks' and clothing, would typically need less than 10 watts inside a car, levels where the inefficiencies don't matter so much:

    http://www.gerbing.com/
    http://www.thunderboltsocks.com/
    http://www.soldiercity.com/product-exec/product_id/9866

    Bob Wilson
     
    #3 bwilson4web, Nov 21, 2007
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