How to POWER on a FLASHLIGHT With FIRE and ICE!

Ever wondered if you could generate electricity without batteries or solar panels? In this fascinating DIY science experiment, I’ll show you how to turn on a flashlight using nothing but fire, ice, and a thermoelectric cooler. It’s a great way to explore the Seebeck effect — the principle behind thermoelectric generation.

What You’ll Learn:

1. How a thermoelectric cooler (TEC) can work in reverse to generate electricity
2. How to safely apply heat and cold to create a temperature gradient
3. How to power low-voltage devices like LEDs or small flashlights using no batteries

Material needed:

1. TEC1-12710 (Peltier module)
2. Flashlight
3. Candle
4. Ice cube

The thermoelectric cooler (TEC) typically consumes electricity to pump heat from one side to the other. But if you reverse the process — by heating one side and cooling the other — it produces electricity due to the Seebeck effect.

The Seebeck effect happens when two different metals or semiconductors are connected at two points, and those points are kept at different temperatures. This temperature difference causes electric charges to move, creating a small voltage. It works because heat makes electrons (or other charge carriers) flow from the hot side to the cold side. The effect is used in devices like thermocouples to measure temperature and thermoelectric generators to turn heat into electricity. The size of the voltage depends on the materials and the temperature difference between the two ends.

Identify the hot and cold sides of your TEC1-12706 module. If you don't have a power supply, you can still identify the hot and cold sides of a TEC (thermoelectric cooler) by looking at the module itself. On common models like the TEC1-12706, the side with the printed label is usually the cold side, and the opposite side is the hot side when the TEC is powered with the correct polarity (red wire to positive, black to negative). Since you don’t have a power supply to test it directly, you can rely on this labeling rule or look up the datasheet for your specific model.

You can use a small pot to put the candle inside. Then on the top you should place the TEC - just like below picture.

1. Keep the flame about 1–2 inches away from the TEC, and heat slowly.
2. Do not touch the plastic or ceramic surface of the TEC directly with the flame, as this can crack or destroy it.

Safety Note: Never heat the TEC too quickly or too much. They’re designed for low-temperature differentials (typically under 100°C).

Place an ice cube on top of the cold side of the TEC and make sure it’s stable and has good surface contact. Just remember, the cold side is meant to be in contact with what you're cooling, and the hot side might need a heat sink to release heat.

Connect the wires from the TEC to your LED flashlight or LED. You may use a multimeter to measure the output voltage — typically you’ll see 1V–2V depending on the gradient.

If you use an LED, make sure it’s low-voltage (~1.5–2V) and correctly polarized. As the hot side heats up and the cold side remains chilled, the temperature gradient across the module will generate electricity. Your LED or flashlight should start to glow as the module generates power.

Once you are sure which are the positive and negative parts of the flashlight you may solder the RED wire (+) to the flashlight. Take the picture as illustrative example.

⚠️ Safety Notice - This experiment involves open flames and ice, which can cause burns or damage electronics if not handled properly. Always conduct the setup on a non-flammable surface, with adult supervision if necessary.

1. Use stronger heat sources (e.g. a spirit lamp) and more stable cold packs for a greater gradient.
2. Ensure good thermal contact with heatsinks and paste.
3. Stack multiple TECs in series if you want more voltage.

With just fire, ice, and a thermoelectric cooler, you can generate real, usable electricity. This is a great project to explore physics, renewable energy, and hands-on engineering.

If you liked this, consider subscribing and exploring more science experiments that bring textbook theories to life!

You can explore more videos like this one! Have a look:

Thermoelectric Cooler (AMAZING SCIENCE EXPERIMENTS)

Building a DIY Thermoelectric Generator (TEG)

How to power a LED through heat (Thermoelectric Cooler)

THIS makes ICE IN SECONDS!