Candle Powered Lantern Isn’t As Silly As You Think

[Gilles Messier] at the Our Own Devices YouTube channel recently took a look at an interesting device — an electric lantern powered by a candle. At first glance, this sounds completely absurd. Why use a candle to power LEDs when you can use the light from the candle itself? This gadget has a trick up its sleeve, though. It lets candle light out and uses the heat from the candle flame to generate power for the LEDs.

The small Peltier “solid-state heat pump” module in the lantern acts as a thermoelectric generator, converting heat from the candle into electricity for the LEDs. The genius of the device is how it handles the candle “exhaust”.  A bimetallic disk in the chimney of the lantern closes when the air inside the device is hot. The Peltier device converts the heat differential to electricity, causing the air inside the lantern to cool. Meanwhile, the candle is beginning to starve for oxygen.  Once the air cools down a bit, the disk bends, allowing stale smoke out, and fresh air in, allowing the candle to burn brightly again. Then the cycle repeats.

[Gilles] does a deep dive into the efficiency of the lantern, which is worth the price of admission alone. These lanterns are pretty expensive — but Peltier modules are well-known by hackers. We’re sure it won’t be too hard to knock together a cheap version at home.

30 thoughts on “Candle Powered Lantern Isn’t As Silly As You Think

  1. It’s comments like this that I vowed I’d never contribute any article or project ideas to Hackaday. This lantern is a real product that has positive reviews (go look it up before you make snide remarks).

    1. Well… never mind. The comment I was responding to was taken down. My comment still is valid though. There are way too many naysayers and arrogant commentators roaming this site.

      1. There are too many naysayers and arrogant commentators on the Internet.

        On Hackaday, however, you can report negative / insulting comments using the “Report comment” button, and if a few people do the same, the crappy comments automatically disappear and go back into our moderation queue.

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  2. I saw this when it came out several years ago, and went through the arithmetic: I can buy disposable AA cells to power the same amount of LEDs, and still come out ahead in weight and cost. With rechargable lithiums, it’s just a no-brainer. I can carry more lumen-hours in rechargeable batteries than I can carry in tea lights.

    1. You have a point, but think of this scenario:
      store both in a closet for ten years and see which solution still works, your high power rechargeable batteries or the one based on fire…

      Fun little device, cool to see it here on hackaday

      1. You can also I expect replace that tea light candle with almost anything else that burns relatively easily. So should you ever be without candle but have some oil and anything that can act as wick (though some oils and alcohols won’t want/need a wick anyway). I wonder how bad the soot build up is and if that flap actually extends the burn time.

        As a light source that is functional, reliable and practical for all occasions I’d not rate this particular implementation all that highly, but it certainly is interesting, looks good and works. It is the sort of thing I could see having for your off grid cabin/caravan quite happily – you might not expect to use it all that much, but when you need a light and your usual generator is dead this is a good compact and attractive backup, along perhaps with one of those gear wind up or shake powered torches.

        1. A slightly larger one, possibly even with a USB charging output option (even if it’s just a slow charge) actually sounds moderately useful and cute. The heat that’s lost isn’t actually wasted anyway if you’re off-grid when it’s not warm.

          I will say that his efficiency numbers are probably way, way high: I highly doubt that thing’s capturing more than a few watts of heat – maybe even less. There’s no reason you can’t scale up the number of thermopiles though: the whole thing’s getting hot, after all.

  3. I’m not sure the host understood the function of the bimetallic flap. He claims its movement regulates the “flow of air” through the lantern and that it is nominally open, but closes when heated by the candle. Furthermore he implies that the function of this is to control the amount of available oxygen in the lamp, so as to throttle the candle flame.

    However, at 9:12, the lantern cold and it appears to me that the bimetallic disk is closed. I don’t think the disk acts as a damper to throttle the candle at all. Rather I think it acts as damper to control the peltier hot-side temperature by regulation how much heat is trapped at the top of the flame column. Thus, you WANT it to be closed while cold. Then, as heat builds up (and if it becomes excessive) the disk can open allowing trapped heated air to escape.

    1. It appears to me to be open when cold. At 9:12, I see the disc having a bowl shape with a gap between the rim and the top surface of the fire box.

      Are you seeing it differently?

  4. I am shocked I tell you – 22 comments and not a single person has said they should have used a 555 timer – shocked I say

    Actually in many of the articles the comments have as much information as the original articles . Keep adding the extra information

  5. This may not may not be useful in your home, but it seems perfect for tables in a restaurant with dimmed lighting. You have the ambience of candle light plus extra light from the LED top for reading the menu, without needing batteries or a power cord.

  6. candle gives up more than 99% of it’s energy as heat…
    even if your teg/light system only got a 5% efficiency, you’re already dealing with an order of magnitude of light more…. and convenient, placeable as you want, directional if you prefer…

  7. I have a commercial version from some years ago (“Luminiser” – still made and sold, though they’ve apparently gone to an oil-lamp system) and…it’s actually kind of neat in a power outage or nice evening on the patio. As others have said the flame has an excess of heat energy so even a poor conversion of that adds a good deal of illumination. Lots of fun to light the candle and as things warm up the secondary lighting takes over in a nice way. I’ve made a few versions previously using cooling modules and LEDs but this one has a place of honor just because it isn’t a rats nest of wires :-)

  8. I have this exact model, and yes it works very well.
    I only get it out during winter though, and I have it lighting up the wall beside my TV.
    From memory I think it was made in Canada.

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