Scavenging From Consumer Electronics To Make A Flame-powered Phone Charger

[Gigafide] just finished building this flame-powered phone charger. The concept is not new. He grabbed a Peltier cooler and used the temperature differential between a flame and a heat sink to produce electricity used by the charger. If you search around here enough you’ll find plenty of candle-powered devices, and a few hacks that use a Peltier device in a bit more interesting way. But we really like his high-production value video, straightforward explanation of the concepts, and ability to source the components in consumer devices. We don’t think you’ll be disappointed by his video found after the break.

The Peltier device comes out of a USB drink chiller. It is supported by a metal stand made from electrical box covers and threaded rod. Underneath he’s using a gel fuel can used by the food industry, and above he’s got  CPU heat sink and fan. This setup puts out around 1.5V but he’ll need a boost converter to charge a phone with that. A single AA battery charger meant to power your phone in a pinch is perfect for this application.

32 thoughts on “Scavenging From Consumer Electronics To Make A Flame-powered Phone Charger

  1. I wonder if I could build this thing on a stick so I could charge my cell over a campfire? (Roasting Marshmallows and charging your phone, now THAT’S multitasking!)

  2. With a bit of searching on ebay I just spent a total of $5 and now have the same peltier device and AA phone charger on the way! Don’t you love it when you find something for far less than you expected to pay? :)

    I am going to try to rig this up to my Fresnel lens since I’m positive it outputs more heat than the cooker.

    If it turns out well I’ll post the build.

    1. How many watts is the peltier device that you bought? I saw some 136W and some 400W and the prices are way too different. I’m wondering what was the wattage of the chiller/warmer mentioned in the original hacker/poster

  3. if you put all of the components onto camp fire, it wont work since the peltier only generates power if there is temperature difference on the twio sides of the Peltier. iI’m wondering how much current we get out of tge device though. $55 is a bit expensive considering you could probably make a solar phone charger for less

    1. Yea, good point, keep the hot side hot and the cold side cold (remember those burgers at McDonalds, maybe a copper pipe attached to the hot side and stuck in the fire, let conduction do the work.

  4. small (garden light) solar cells are great when you can get a lof of em, and one little garden lamp unit could partially charge a phone
    (turn phone completely off and wait til next day to charge more next day til full)

    but LARGE panels are nessasary to charge a cellphone from flat to full in one day of sun


    12v peltier beer coolers (okay, well actually just the peltier element inside) found at the store usually survive a house collapse, once you dig it out…

    to completely charge most cellphones, you would need at least 2 or 3 or 4 AA battieries in a row using the single-AA-battery charger, it is meant for emergencies and thus overdraws and damages the battery (wastes power)
    (battery warms up, energy for heat comes from…)
    (…and heat affects the battery chemistry…)

    nobody likes pedal power

    1. a fair amount, considering how dinky solar cells can seem in anything other then full on direct constant sunlight.

      ps peltier can be run 24/7 as opposed to the solar at around 0 – 12 hours on a roof and 0 – 6 hours or less in a typical garden beside a building

  5. The video doesn’t mention it but the Peltier elements are made of small semiconductor blocks soldered to the ceramic plates, so be sure not to heat it up too much.

    One possible improvement would be to power the fan using the Peltier element itself to cool the cold side more, since their efficiency increases with the temperature difference across the two surfaces. Something about Carnot’s theorem :-)

  6. Yeah, I’ve run into this effect too.

    Those nice multiple stage Peltier cryocoolers need something like 50C max on the hot side to get peak efficiency, which needs active water cooling.

    I did however find that one way to boost Peltier efficiency is to pulse them, seems that there is such a thing as thermal inertia.
    Tried it and 12V pulsed at 6A for 10% duty cycle gives marginally higher efficiency than continuous 12V at 1A.
    Could be similar to LEDs, the efficiency falls off as the elements heat up internally so pulsed power could be effective for some applications.

    Sir Clive Sinclair also discovered the IC related effect to make his calculators last a month off one battery by chopping the power rapidly.
    Seems the chip didn’t need power all the time, only when the output states changed.

    1. Can you provide the numbers that what that “marginally” means? I would be interested.

      Do you think that this cycling would work in reverse? I mean that would cycling power on and off change the termal efficiency allowing to go lower temperatures for example?

  7. Another related idea, heat up the “hot” side of the Peltier using biofuel such as decomposing organic matter.
    Not so stupid as it sounds, compost can heat to nearly 85C and sometimes over 100 by simple bacterial action.

    You can also make primitive thermal power cells using pieces of copper wire coated in oxide or sulphide, a Russian version of this powered a valve radio from a candle.

  8. No one has mentioned how horribly ineffecient peltiers are. Less than 30%. I know if you put in 10 Watts of power through the petier leads you only get 3 Watts of cooling out of it. How does the reverse work… if you heat the peltier with 3 Watts via the flame do you get 10 Watts out?! Or I guess is it generating a temperature differential comparative to 3 watts of cooling that you could get 10 Watts of power out?

      1. Assuming mass energy equivalence then there is conservation of energy. If that thing was whomping out more energy than was put in we’d all have free electricity.

      2. “If that thing was whomping out more energy than was put in we’d all have free electricity.”

        Look it up, it does exist, and it does put out more energy than goes in. It does require a fuel: Hafnium(178) (half-life 36 yrs), and an ignition source: X-rays.

        Cheap maybe, but by no means free.

        …And I do think, that you just might be under-estimating corporate fascism in joint partnership with GREED, that simply WILL NOT let this happen; nothing personal…just business.

      3. What do you think the fuel is for? The reactor hasn’t created any energy, when you put your fuel in you put a stonking great energy store in the equation. The 1:60 refers to the x-ray radiation energy put in compared to the stored energy released from the fuel. No energy has been created.

        What you’re saying is the equivalent of saying, I lit that barrel of petrol on fire with a match which produced 1 joule of heat energy. I now have 1000 joules of heat energy produced from the resulting explosion therefore match and petrol reactors have an input/output ratio of 1:1000.

      4. Think your missing my point…
        No matter how you want to state it, your getting a LOT more energy out than your putting in…30 years worth. The statement, “you can’t get more energy out than YOU put in” IS flawed. How much energy was put into mining that little bit of fuel (Hafnium(178)), and the electricity used to produce the X-rays(ignition), verses the energy your going to receive?

        I do know what you are trying to say …fact is, it just ain’t so.


      5. You argument would be exactly the same if you substituted energy for money. When you say the energy you put in, you’re taking it to mean your personal energy expenditure. When I say it I mean total energy present that has been introduced into the system.

        If you had to make the hafnium, not mine it, you would find it is not an efficient method of generating power.

    1. I’ve done academic research on thermal energy scavenging for low-power electronics (wireless sensor networks). Manufacturers make TEG devices (thermoelectric generators), which is just a peltier with higher-temperature rated components.
      In the real world, you’ll get less than 5% efficiency from thermal to electrical energy conversion.

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