I’m trying to understand if there is a way to store energy created by magnets and a coil in a circuit in say.. a rechargeable battery?

Question

So basically I have watched videos on how to light up a little LED lightbulb by having a coil and rotating magnets etc.. but instead of that energy being used to light up a little LED, is there a way to store that generated energy to use at a later time in for example a battery?

Quite new to this but it interests me.

Answer 1

Yep, that's how a "dynamo torch" works.



They have a tiny generator turned via gears from a crank handle, plus a rechargeable battery.



Example:

https://www.clasohlson.com/uk/Varta-LED-Dynamo-Torch/36-3739





Another version, opened up; you can see the dynamo on the right (probably just a basic permanent magnet DC motor used as a generator) and the battery on the left, with the green insulating sleeve:

http://brainmedley.com/blog/wp-content/uploads/2008/08/geartrain.jpg





You can also get eg. wind-up radios that run from a little dynamo.





On a larger scale, that's how a car electrical system works - a dynamo (or now alternator) powered by the engine, that charges the vehicle battery and also runs the electrical system while the engine is running.



A dynamo or alternator is just a combination of coils and magnetic field, one rotating relative to the other.

Answer 2

Magnets and coils is exactly how a power-station creates electrical power. Yes, a battery will store energy. As the power from a "magnet and coil" generator is AC, you first have to convert it to DC at a suitable voltage. A bank of capacitors is not very efficient as a capacitor has a relatively tiny capacity in terms of ampere hours, and is rather leaky. I suggest you call the nearest Generating station and ask if they do tours of the station. It will be interesting. Also visit the electrical section of a science museum.

Answer 3

That will, to a large extent, depend on the design of the generator.



In the simplest solution, all you'd need would be a sufficiently large battery and a diode. "Sufficiently large" so that any overcharging will not damage the battery.



On the other end of the spectrum would be an MPPT (maximum power point tracker) circuit trying to get the maximum power from the generator in order to charge the battery.



For example: if your generator is a bicycle (hub) generator, the simplest solution would be to hook it up to a 6V/5Ah lead acid battery via a diode. Unfortunaely, such a battery would be large and not very vibration proof (i.e. die quite quickly when mounted to a bicycle - BTDT). If you want to go beyond that, the options become varied and rather complicated - if your German is up to it, you may try to Google for the Forumslader, a bicycle generator powered battery charger that has evolved from a simple bridge plus zener diode to a microcontroller controlled LiIon charger with Bluetooth connectivity :-)

Answer 4

You need to select the type of battery so that the voltage from your generator is slightly above the voltage of the battery.



You need a diode in series to stop the battery discharging through the generator when the generator is not turning. E.g. try the video in the link.

Answer 5

Of course there is. The problem is building the control circuit to make sure you do not overcharge your battery.

Answer 6

Congratulations. You have just invented the storage battery. Oh, just a minute, though . . .

Answer 7

Yes. A coil and magnet working together like you describe is a basic generator. Once you have some way of producing electricity, you can use it for whatever your need is. And that does include charging a storage device such as a bank of capacitors or a battery.