How do those batteryless radios or flashlight works?

Question

I've seen these radios or flashlights at Costco or somewhere in which you just wind up the crank and the radio supposed plays for about 1/2 an hour and they sell it for in case of emergency. How does it work without batteries?

Answer 1

its a small generator. the radio takes more electricity and requires more mechanical energy to charge than a flashlight because the flashlight uses a low powered led that doesn't release the kind of heat that a regular light bulb would.

Answer 2

Many of these devices no longer have any batteries to charge. They have what is called a clockwork drive.

What happens is this: when you crank up the radio or flashlight, you are winding up a clockwork mechanism, like on a wind-up toy. When you let go of the crank, the wind-up clockwork motor drives a generator, which runs the radio or flashlight. You just need to keep winding it up every 20 minutes or so. This way there are no batteries to decay.

Answer 3

They are not exactly battery-less. They still have batteries. What you are doing when you turn the crank handle is turning the armature on a small electric generator in the flashlight or radio. This generates electricity which is used to charge rechargeable internal battery.
So what you are doing when you are turning the crank is turning the generator recharging the battery.

Answer 4

technically, those devices do have batteries (even if it's in the form of capacitors). Winding the device spins a magnet near coiled wire, which produces elecriticty, which is then stored in a unremovable battery for later use.

also, AM radio's can even be powered using the radio wave signal! a bit quiet though without amplification, which requires extra power.

Answer 5

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Answer 6

Its a magnet. Magnetic fields can produce electricity when they are run by a wire. inside the flashlight you have wire that is coiled up. Inside the coil is a magnet that produces electricity when you shake it. This electricity doensn't last forever so you have to shake it for a while after each use.

Answer 7

when you crank it a little watch type battery in side gets charged witch in theory actualy loses charge and power capabilities causing it to take longer to fully charge and it wont keep its charge as long