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This product (Japanese language) is claimed to cool down your smartphone, etc, battery by two degrees centigrade - see the photo a little way down the page.

It claims to be a graphene-based material, and looking on the web I see lots of articles about how graphene is an excellent heat conductor, and would work well for CPU cooling fins.

However, reading the small print, it suggests sticking it directly on top of your battery, underneath the cover, if you have one - this would appear to negate any cooling effect as there is nowhere for the hot air to escape to, and furthermore outside the case, your hand is going to be on top of the sticker, so if anything it would transfer heat from your hand to the device!

It is referred to on this English page:

Thanko has released a sticker they call the “Mobile Heat Sink” for cooling down a heated smartphone, PC battery, tablet, game device etc. Just by attaching it on a device, it can make it cool down by about -2 C degrees.

However, it isn't clear that this English site has any direct knowledge of the product.

Overall, I get the impression that this is a variant on the EMR-eating sticker scam. Is my skepticism justified?

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Ken Y-N
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  • No data (none would exist...), just logic, hence a comment: where would the heat go? There's no heatsink (not even cooling fins which would be ineffective given the positioning) for the heat to flow to, so it stays in the device. Which of course is the exact same conclusion as with the EM eaters (almost, if those worked the phone would stop functioning, giving even more reason to conclude they don't work). – jwenting May 13 '13 at 05:41
  • Clearly nonsense. Also note that Japan has VERY lax advertising truth standards compared to most Western countries. The supermarkets are replete with wondrous weightloss scams. – Drew May 13 '13 at 06:15
  • 2 degrees C is equivilant to about 3.6 degrees F just to give an idea about how small a difference it is – ratchet freak May 13 '13 at 07:29
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    If there is a gap between battery and cover and that material would fill in that gap. That's assuming that the cover is good at transferring the heat out. There used to be "phase-change thermal pads" for CPUs, but they seem to have lost to thermal paste. – vartec May 13 '13 at 09:34
  • Doesn't it mean that it makes the *battery* cooler by 2C by making the *enclosure* slightly hotter? – Sklivvz May 13 '13 at 10:53
  • @ratchetfreak wrong argument. 2C under most operating conditions would mean a 10% drop or more in temperature, not trivial at all. – jwenting May 13 '13 at 12:58
  • @Sklivvz which by the laws of thermodynamics would mean the energy flows back into the battery to equalise energy levels. Could have an effect, IF the added material provides enough volume to contain the energy needed for dropping the temperature of the battery that much, maybe, but then of course it would be highly dependent on outside air temperature and airflow both of which influence the case temperature. – jwenting May 13 '13 at 13:00
  • Graphene is weird stuff, most of it's physical properties---including thermal conductivity---are anisotropic. I believe it conducts heat much better in plane than out of plane. In principle efficiently spreading the heat laterally means a larger surface area over which to dissipate it and you could get a (presumably small) win. Of course, you have to get the heat into the gaphene and then out again for this to have a chance to work and it must not be overwhelmed by the effect of whatever matrix you wrap the stuff in. – dmckee --- ex-moderator kitten May 13 '13 at 14:23

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