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Thermal thoughts

Discussion in 'Technical' started by malcolm, Jun 5, 2008.

  1. malcolm

    malcolm Active Member

    Joined:
    Nov 12, 2006
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    Been thinking about parking..

    ...so there's this expensive, thermally compensated battery pack sitting just behind the seats and quote "Our cooling system engages to try and keep the temperature of the cells below 35° C at all times and the lifetime average temperature at or below 25° C" and yet the panel which covers it and the shelf above with the hi-fi speakers are all black. If the car is parked, there is no cooling system (unless I've missed something)

    Obviously if the roof is off, then it's a battle between incident solar radiation and ambient air cooling - so is the rule to always park with the back of the vehicle facing the sun? Does bodywork colour make any sort of difference in this situation?

    If the hardtop is on then, as with any car, irrespective of body colour (or interior colour) the centre of the vehicle works like a greenhouse, allowing heat to build up and be conducted to the rest of the vehicle over a couple of hours. Is a (typically black) soft-top better or worse at this greenhouse effect?

    I know Aptera intend to use a roof mounted solar panel to operate fans for the interior, but isn't a cheaper method just a suitably reflective sun cover?

    Custom Sunshields in Reflective Mylar Foam Mylar

    mafe.co.uk: Waterproof covers for Lotus Elise S1 & S2
     
  2. Kardax

    Kardax Member

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    Location:
    Minnesota, USA
    Heat rises, plus the windshield has an infrared filter on it, so sunlight isn't likely to cause any heat problems with the battery so low in the car.

    The serious amounts of heat would come during charging or operation. That's when the cooling system matters most.

    -Ryan
     
  3. deenko

    deenko Member

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    In a worse case, the roadster will turn on the cooling system to keep the pack cool. Think about it though, the pack is a huge thermal mass in a protective case. Sitting in the sun, it would take hours for the pack to heat up a little bit just from solar energy.
     
  4. malcolm

    malcolm Active Member

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    Interesting. Hadn't thought of the cooling system turning on even when the car is unattended.
     
  5. deenko

    deenko Member

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    You know, on second thought, I do not think that it does turn on, mainly due to the fact that it takes too much heat to make it rise in temp.
     
  6. malcolm

    malcolm Active Member

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  7. vfx

    vfx Well-Known Member

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    That's cool!

    If I had the wherewithal, I would do something like that.

    But I'm a bit weird (my wife uses the word "eccentric" but I don't think we have enough money to carry that title either.)
     

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