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heated seats project begins in '08 Prius

Discussion in 'Gen 2 Prius Accessories & Modifications' started by navguy12, Feb 3, 2012.

  1. navguy12

    navguy12 Member

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    #1 navguy12, Feb 3, 2012
  2. Turdblossom

    Turdblossom Junior Member

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    Great write up! You have excellent skills!
     
    #2 Turdblossom, Feb 4, 2012
  3. navguy12

    navguy12 Member

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    Thanks. My OCD put to constructive use.......:)
     
    #3 navguy12, Feb 4, 2012
  4. cnschult

    cnschult Active Member

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    It looks like you are doing a lot of work to put heated seats in a car with cloth interior, is this so? Isn't the point of cloth is so the seats are comfy year-round? So they're not hot in the summer or cold in the winter like a car with leather seats.

    I had a gen III prius five for just under a year and it had leather seats, I never bothered with cabin heat, just the heated seats and it was very nice with the leather; but the gen II Prius has a problem with moisture build up on interior glass surfaces from snow melting off your boots, so you are pretty much forced to run a gen II Prius with cabin heat in order to attempt to dry out the interior as much as possible. So isn't cabin heat with a cloth interior enough??
     
    #4 cnschult, Feb 5, 2012
  5. navguy12

    navguy12 Member

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    Good observations all.

    (1) I had cloth in the HCH II and I installed heated seats, kept the climate control system at bare minimum and comfortably drove five winters with little/no heat.

    (2) By use of 3D floor mats (Floor-liners, with non-permanent caulking used for waterproofing the floor-hook holes) and newspapers as absorbers being swapped out as required (!), no winter induced melting snow or other moisture ever gets to touch the carpets so wet carpets are not an issue.

    (3) Preliminary tests are showing me that I can drive under pure electric power from leaving the garage until departing our rural community (luxury of speeds of 30 kph) when no cabin heat called for, so electric seats will make the first 90 seconds that much more comfortable.

    (4) I note the comments in other threads regarding the fogging and/or flash freezing of moisture on the interior surfaces of the glass, etc.

    My hypothesis (not enough data points to assert at this time):

    The intake air vent (located at rear right passenger shoulder area) for the battery module is acting as a chimney once the vehicle is motionless and flow thru ventilation plus the module exhaust fan no longer 'suck' the warm module air out. This chimney effect is letting the residual module hot air rise out of the intake vent into the cabin. Said air then touches the glass and immediately condenses.

    For the scenarios in my daily driving that may result in this situation, I'll crack all four windows and see what happens.

    Thanks

    Cheers

    Mike
     
    #5 navguy12, Feb 5, 2012
  6. cnschult

    cnschult Active Member

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    I think your newspaper on floor idea is very clever but that's a little too dirty for me, and I have very deep rib rubber mats and any newspaper would make things very slippery when getting in or out of my car, a couple times a week I take my rubber mat out, rinse it in the sink and let it dry out overnight, I then stick a space heater in the cabin to dry everything out. Its just a perk of having a garage.

    I am in aviation and have been given basic meteorology training and allow me to explain the flaws in your theory. First, the air around the battery will be warm and dry, you may think that warmer air is more humid than cooler air, which is why humidity is higher in the summer. But warmer air actually has the ability to hold more water, that's why dew point is lower than the actual temperature. e.g. if the news says its 40 deg and the dew point is 25 deg, that means that for the volume of water in the current airspace around your city, it is not enough to cause precipitation at 40 degrees, but if the air temp falls by 15 degrees, the colder air is less capable of holding onto that volume of water, and humidity will rise to and exceed 100%, and precipitation may ensue.

    so when you turn off a Prius, if in fact you are correct and warm air leaves the battery compartment and returns to the cabin, it would raise the temperature by say one or two degrees, that would lower the relative humidity of the cabin as the cabin now has increased its capability of holding water.

    So if anything warm air from the battery compartment is helping to prevent (unsuccessfully) interior glass frost on a Prius. The best idea is to make sure the a/c compressor is running with the heat, the dehumidifiers most of us have to run in our basements in the summer is basically a small air conditioner.
     
    #6 cnschult, Feb 6, 2012
  7. navguy12

    navguy12 Member

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    [FONT=&quot]
    I hear you. The garage makes these little projects so much easier.
    Cool, what do you fly? I flew in the RCAF for 28 years on the Canadian equivalent to the P3-C and the C-130 Herc.
    100% agree. And when that warm dry air rises, it begins to cool (ISA rate of 1.98C/1000 feet) to match the surrounding air-mass temperature. At a certain point, that (once warm, dry) air will no longer be able to hold the moisture in it (temp/dew-point become the same) and the air condenses.

    Example: American south-west desert areas (very hot and relatively dry), one will see cumulus clouds pop up and their bases are all the same relative level (the dew point)

    What happens when that warm (dry) air that surrounded the battery pack touches a cool window surface?

    The (very little) moisture in it condenses out on the inside of the glass.

    Again, I have yet to test my hypothesis before I can elevate it to a theory.

    But I did park the car outside at my Yoga class last week and when I came out all the windows were fogged up:(. Trouble is, the carpets are bone dry.

    I may try laying a waterproof foam pad over the intake vent when parking the car outside next time......just see what happens.....if it has no effect, then back to square one.......

    Cheers


    [/FONT]
     
    #7 navguy12, Feb 6, 2012
  8. navguy12

    navguy12 Member

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    #8 navguy12, Feb 11, 2012
    1 person likes this.
  9. drew935

    drew935 Member

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    I could see doing this mod if my wife really wanted heated seats. Thanks for the write up!
     
    #9 drew935, Feb 11, 2012
  10. navguy12

    navguy12 Member

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    I find they do cut the needed ICE heat....today its -11C and I still got 4.9L/100 km over the day....
     
    #10 navguy12, Feb 12, 2012
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