Aluminum Foil Heatsink Keeps LEDs in Check

In your kitchen is very likely a roll of aluminum foil, like most people you probably use it to line pans or wrap food for baking. If you heard somebody used aluminum foil in the cooling of items, you could be forgiven for thinking they were referring to wrapping leftovers and tossing them in the refrigerator. But rather than preserving Mom’s famous meatloaf, [Michael Dunn] is using that classic kitchen staple to protect his LED strips.

Cheap LED strips are becoming extremely popular and have been popping up in more and more projects, but they have a pretty serious flaw: heat dissipation. Left on their own they can get hot enough to cook themselves, which is sort of a problem when you’re looking to replace as much of your home lighting with them like [Michael] is.

Heat was of particular concern as he was looking to retrofit a delicate shade with his beloved LED strips. Since he wanted a column of LEDs inside the unique shape of the shade, he reasoned that some kind of heat-conductive tubular structure could be used as both a mandrel to wrap the LEDs around and a way to dissipate heat. Like most of us, his first thought was copper pipe. But unfortunately the only copper pipe he had handy was of too small a diameter.

The tube of foil on the other hand was the perfect diameter, and while aluminum isn’t as good a conductor of heat as copper, it’s certainly no slouch either. Early tests weren’t that great when the tube was laying on the bench, but once it stood vertically convection got the air moving and cooled the LEDs down to where [Michael] was comfortable enough to put them inside the shade. Though he does have some lingering doubts about leaving the cardboard tube in such a toasty environment.

Going back through the archives, we’ve seen some absolutely fantastic projects utilizing LED strips in the past, some of which have come up with their own creative ways of beating the heat.

24 thoughts on “Aluminum Foil Heatsink Keeps LEDs in Check

  1. That’s not a heatsink, more like a heat bucket, as the aluminium is surrounded by the heat source and so cannot dissapate much anything.

    Many people make the mistake of thinking that simply bolting a LED onto something metal will keep it cool. You also have to keep the metal cool somehow. It does no good if you then surround the heatsink with cardboard or hide it inside some enclosure where it cannot dissapate the heat.

      1. Or just spend a few dollars on an aluminum shower curtain rod.

        If the tube gets to any appreciable temperature, it will cool itself via convection provided it’s oriented vertically…

    1. Exactly!
      At least if he removed the cardboard, and added a few holes near the bottom, he’s got the possibility of convecting air up the middle of the Al roll. Not the most efficient within that shade, but it will certainly help.

    2. Maybe the word ‘heatsink’ is a little faulty, too.
      It suggests to drain heat like water in kitchen sink but some seem to forget the ‘drainage’.

      heatdisipater / -distributor / -transporter seem like more apt alternatives…

    1. There’s gaps, but you’ve still got ~85% of the back of the strip pushed against smooth foil so it works.

      I don’t think anyone is suggesting a pipe wouldn’t be better, the idea is that he used what he had in a pinch which is somewhat of a theme here on the site.

      1. So you’ve got ~85% contact to a thin sheet, looping away while short-circuiting thermally to ? % surface area to the next layer, etc.. Does something for startup, but it has limited thermal mass. Without removing heat from the foil wrap, removing heat from the LED devices will only work (well?) for a limited time, as the temperature differential between the foil wrap and the LED strips drops so the removal of heat from the LED strips drops. All that method has really done is delay the issue or give somewhat more life with slightly reduced baking. I wouldn’t call this “works”, but “works for now; gonna bake”.

    1. I was just thinking about this last night – could you just wrap copper tape around an aluminum can to heatsink some LEDs for a lamp? Would you need a layer of insulation under the copper tape to prevent the traces from shorting through the aluminum, or would the paint and oxides and stuff prevent that?

  2. I installed LED strip lighting in our boat, and never considered the heat implications. Is it the case that the strip will often overheat when installed as a strip, instead of being coiled as shown?

    Fortunately, we found them too bright at full power, so I made a PWM dimmer with a PIC microcontroller. We seldom run much higher than a 50 or 60% duty cycle, and they’ve never seemed more than slightly warm.

  3. Pretty amusing. In the flashlight enthusiast community, aluminum foil is sometimes used to couple the LED with the flashlight body for better cooling. Just wrap up the LED/reflector area so that it fits snuggly.

  4. I am not sure about the numbers on this, but even more, the LEDs on low power strips like this are in plastic casings anyway.
    It is true that the LED might heat, but it is terrible at transferring the heat to anything including the strip anyway. So air cooling is still the most important.

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