Releasing mechanical energy over time

greyd927

lets say i wanted to store it for a day. I wouldn't mind being able to go longer, but a day would be pretty ideal.

Drakkith

Well, now you have me confused. What's wrong with normal batteries? I thought you wanted to store it for much longer than a month or two. Batteries would work great for storage in this manner.

greyd927

A spring or coil can be rewound over and over again whiteout the need for external electricity. Batteries only have one use or require existing electricity to recharge them.

And if i wanted to store it for a day the design could easily be changed to store it for a few months or even a year. Potential energy is pretty easy to store. A day is just a really simple easy interval to start out with.

jim hardy

none of my business - just a thought that wanted out....


my '49 Buick clock used a pull spring about 3 inches long that got re-stretched by an electromagnet every fifteen minutes or so.

Going opposite direction - take apart one of those "Shake" flashlights and experiment with its magnet-coil-supercapacitor ? A mousetrap could yank the magnet through the coil to charge your capacitor after years of waiting.

I dont know how much voltage shake-flashlights make, or whether it'll deliver the current you need.

greyd927

Thats the general idea I'm going for- stored mechanical energy converted to electric, the problem is something like your mouse trap example would provide energy for just a brief moment where i would need constant power output for about an hour :/

Drakkith

True, but you are wanting to convert your potential into electrical energy anyways, and it's pretty much all the same components on the electrical side. Whatever is winding your spring could easily be made to generate electricity to charge a battery.

But in the end it's your idea. I don't want to discourage you, I just don't want you to do a lot of unneccessary work. There are plenty of other options. Flywheels, weights, water storage, etc.

greyd927

The idea is to be able to have on demand power for small devices dispute power outages and what not hence why mechanical energy is my approach

Drakkith

If you are converting the power to electrical power anyways, why would storing the energy mechanically be your approach? Batteries are smaller, lighter, can hold more energy, and are generally more reliable. You don't need external electricity to charge them, as whatever you are doing to generate the mechanical energy can easily be used to charge the battery.

zoobyshoe

As soon as you start 'tapping' the electricity the magnet becomes harder to move relative to the coil. Lenz's Law. Because of this you might figure out a way to have your generator be it's own governor.

If you extended the shaft of a conventional generator, wound a rope around it, lead the rope up to a pulley, and fastened a big weight onto the other end of the rope, as soon as you put a 'load' on the generator (plugged something in) the generator would become harder to turn, and the weight would descend more slowly. Because of what you're trying to design, that could work to your advantage.

You said all you wanted was to generate 5v, but its really the watts you want that makes a difference. 5 volts at how many amps? If you are looking for 5 volts at milliamps, it sounds completely reasonable and doable to me. If you want 5 volts at one amp, it becomes that much less reasonable, and so on. If you know exactly the thing you want to power you can get the watts and design your weight powered generator for that.