I had a device used for charging a flashlight using power generated from a coil and a magnet. It was a large flashlight tube, in the middle of the tube was a large spun wire cylinder, and a large, very powerful magnet, a supercapacitor, and a bright LED COB CHIP light. The objective was to pump your arm up and down, making the magnet slide up and down in the tube. The power generated was rectified by 4-M4 SMD diodes, then fed into a 1 farad, 5-volt supercapacitor (SC). The only thing I did not understand was that above the SC was a magnetic reed switch. Of course, its function was to open and close the switch during each cycle, but I'm lost as to why. I have also been working towards energy harvesting, so when I saw a device powered by a SC, I wanted to find out how they juiced up the SC with enough power stored to light the LED COB CHIP, so of course, I tore it apart.

Well, there was no magic, just an AC generating coil/magnet, full wave rectified, then fed into a SC, the reed switch was the only questionable thing on the circuit board. I've attached pictures (minus the circuit board). The inside diameter of the tube is 20 mm, and the diameter of the magnet is 18 mm; there is roughly 3 mm of coiled wire. At the top of the picture, I have a small solar panel, fed as the SRC to a e-peas AEM10941 Solar Energy Harvesting IC and stored in a LION battery, I am considering placing 12 MEAS weighted piezo's next to my window to pick up the vibration from cars on my BUSY street, as well as several peltiers I was going to place against my sun-facing window and try to gather power from the heat of the day and cold of the nights (Montana). The system will cover heat, vibration, and light at one time. I've also included the breakout board from PCBWay, I got 15 boards for $5. Here is a link to the board if you're interested.

https://www.pcbway.com/project/shareproject/SolMPPT_Rev_0_0_2.html

So, my first question is, how much power could they possibly generate from the coil and magnet, and how is the power generated and stored and able to power the COB light for more than 5 minutes, and what function does the reed switch perform? I've tried, but I can only get any LED to power for less than a minute, let alone a high-current COB light.

Secondly, what are your thoughts on a small propeller that smacks the MEAS piezo as the wind blows?

Third, what are your thoughts about this blended system? Anything you would change or add?

 

So, my first question is, how much power could they possibly generate from the coil and magnet,

Not a lot. There are practical limits on the speed of the magnet passing thru the coil, and the frequency of that. Maybe a few volts of EMF pulsing at 4 Hz? Those limits cap the energy that can be extracted with each pass and then the total energy per second (power).

...and how is the power generated and stored and able to power the COB light for more than 5 minutes,

Power is generated by the induced EMF in the coil as the magnet passes by. It's stored in the capacitor. The COB has likely been chosen to draw a low enough power to stay lit for several minutes. In other words, the system has been designed as a system, not just components.

... and what function does the reed switch perform?

Not sure. Are you certain it's a reed switch? A picture might help. Is the switch placed in such a way to be actuated by the passing magnet?

Secondly, what are your thoughts on a small propeller that smacks the MEAS piezo as the wind blows?

Personally I don't think you'll be happy with the piezos. The power they'll provide will be orders of magnitude smaller. Interesting maybe but you're already using a device that converts mechanical energy to electricity. I think using the wind to rotate the shake-weight would be more fun.

 

Probably the reed switch is to allow switching the LED on and off. THAT is what makes sense for a flashlight!
I saw an item similar to that a few years ago, and my recollection was that it had to be held a certain way to cause the big magnet to close the reed switch. The concept was that charging the cap and operating the LED could be done separately. The product was marketed as being intended for use in a fallout shelter, which sort of dates it a bit.

 

A magnet like the one in the picture passing thru a coil with that many turns can generate a bit of power. So each pass cold generate a worth while amount f power. It is certainly basic "text book" generation of electrical current.