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Batter Pack Insulation Writeup

Discussion in 'Gen 2 Prius Accessories & Modifications' started by The Banks, Jul 6, 2009.

  1. The Banks

    The Banks Junior Member

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    [FONT=&quot]For those of you have ever driven your Prius on a road trip then you know that passengers in the back and cargo in the trunk can start to heat up.
    The culprit? The kinetic energy from the discharging and recharging of the nickel metal hydride batteries.
    The solution: Insulating the battery pack and making the hot air ventilation from the battery pack to the discharge position located in the passenger side rear bumper/quarter panel area more efficient.

    Before

    [​IMG]


    Taping around the discharge position of the hot air vent to help create a better suction to evacuate hot air efficiently.

    [​IMG]


    Battery pack insulated with bubble foil insulation

    [​IMG]

    [​IMG]

    Insulated underneath the back seat bench with a cutout around the top of the fuel pump, and slits by the seat belts.

    [​IMG]
    [/FONT]
     
    #1 The Banks, Jul 6, 2009
  2. V8Cobrakid

    V8Cobrakid Green Handyman

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    nice mod. i did notice a lot of heat on all my long trips. people actually complained that they were scared to touch the surface below the seat. any way you can test to see how much this install helps? like temp readings?
     
    #2 V8Cobrakid, Jul 6, 2009
  3. yardman 49

    yardman 49 Active Member

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    I only pack batter into pans, not the Prius :)

    Seriously, though, I've never encountered the rear seat/cargo area heating problem. And I just took a 900 mile drive. Is this problem a common one?
     
    #3 yardman 49, Jul 6, 2009
  4. The Banks

    The Banks Junior Member

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    Lol. I know, I know. Right after I hit the submit new thread button :eek:

    I don't know if this is a common problem, but last summer I went on an 400 mile drive from San Diego to Mammoth and got complaints from the back seat passengers and the lid on top of our cooler was warped. I'll be going on a ~3000 mile roundtrip road trip in about a week, and thats what compelled me to do this mod. I'll try to get some temp readings, but don't have any temps from before the mod for comparison. If the cooler lid doesn't warp again then we'll know it helped ;)
     
    #4 The Banks, Jul 6, 2009
  5. 2009Prius

    2009Prius A Wimpy DIYer

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    The battery cooling fan did come on, right? or did it? :eek:
     
    #5 2009Prius, Jul 10, 2009
  6. djasonw

    djasonw Active Member

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    That's weird. I have a 2004 and no one has ever complained about heat in the back seat.
     
    #6 djasonw, Jul 10, 2009
  7. JimboK

    JimboK One owner, low mileage

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    Hmm, I don't think I'd want a blanket around my battery, especially during a southern California summer. Battery temperatures can certainly get rather high in summertime, though I too have never had complaints from rear seat passengers and temperatures certainly shouldn't get high enough to warp a cooler lid. (Did you leave the car parked in the hot sun long enough for heat buildup to warp it?) Despite your ventilation enhancement, my guess is that the insulation would only make it hotter. Once heated, its large thermal mass makes it slow to cool. Heat is an enemy of battery life, and the car's control algorithms reduce battery use above certain battery temperatures, reducing overall efficiency.

    2009Prius asks an appropriate question. You should assure the fan is working.
     
    #7 JimboK, Jul 10, 2009
  8. yardman 49

    yardman 49 Active Member

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    Right now we are on mile 760 of our return trip in our 2009. Passengers report back seat area is not warm at all (we've been rotating driving, and I was back there for a while on the outgoing trip). Outside temp is 81 F. Three adults and cargo packed to the gills (left side rear seat is folded forward with cargo on top).

    Based on this uncontrolled experiment, it seems to me that the overheating behavior posted by The Banks would seem to be abnormal. I agree with Jim that adding insulation around the traction battery would not be a good thing to do.

    Frank
     
    #8 yardman 49, Jul 10, 2009
  9. drees

    drees Senior Member

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    Hmmm, I've never heard of this before and never experienced it, either on long trips with the car filled to the max, too.
     
    #9 drees, Jul 10, 2009
  10. Celtic Blue

    Celtic Blue New Member

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    Those are exactly my thoughts and concerns. Now if it is actually making the passengers uncomfortable I can understand the motivation, but this will be harder on the battery or require greater intervention by the battery cooling system.
     
    #10 Celtic Blue, Jul 10, 2009
  11. efusco

    efusco Moderator Emeritus
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    +2,
    Unless you are monitoring battery temps I do NOT recommend this at all. Perhaps the under-seat insulation, but wrapping the entire pack that way is probably not a good idea in high temp areas. It may offer cool weather benefits to prevent cooling.
     
    #11 efusco, Jul 10, 2009
  12. donee

    donee New Member

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    Hi TB,

    Even if the fan is working, you may have some kinda blockage. Its been reported several times, that malfunctioning Prius' had collections of rodent bedding materials in the vent, and battery case. This could explain what is happening there.
     
    #12 donee, Jul 10, 2009
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