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Howdy everyone, I'm sorry if this is in the wrong forum, but since I believe it is mostly a thermodynamics problem I think this is the right arena. My questions stems from trying to insulate a bank of batteries in cold weather. I am trying to determine the proper material and design specifications for the enclosure I will be building and I've come to a bit of an impasse. Essentially I need to keep the batteries "warm" (greater than 4.5 degrees C) for at least 24 hours with a starting temperature inside the enclosure of around 24C (this can be modified) with an outdoor temperature of -20C. I have yet to take heat transfer, but I have borrowed a textbook and I believe I need to find the allowable R-value and then work backwards from there to determine the thermal conductivity required as well as allowable thickness of the material. I just don't know how to calculate that initial R-value that I will then use to determine if a material is suitable. I believe that I might have to determine the total heat lost from 24C down to 4.5C in 24 hrs? I have a feeling I am missing a formula about the allowable heat loss perhaps? If anyone could help me out I'd really appreciate it!

These are the formulas I think will be helpful:

For R-value: R= ΔT/(q/A)

*where ΔT is change in temperature, A is area and q is the heat transfer rate.

For heat transfer rate: q=(-kA/Δx)*(T2-T1)

*where k is the thermal conductivity of the material, Δx is the thickness of the material

These are the formulas I think will be helpful:

For R-value: R= ΔT/(q/A)

*where ΔT is change in temperature, A is area and q is the heat transfer rate.

For heat transfer rate: q=(-kA/Δx)*(T2-T1)

*where k is the thermal conductivity of the material, Δx is the thickness of the material

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