Using Piezoelectric disk to charge the chargeable battery.

Thread Starter

Momme

Joined Oct 27, 2023
13
Hi, im doing a project on piezoelectric disks where I want to harvest energy from them. I have ordered some and waiting on them, I wonder if someone is familiar with working with these and could answer some questions.

thanks in advance
 

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Thread Starter

Momme

Joined Oct 27, 2023
13
Hi my idea is to make a board with 4 diodes and then connect to a charging module to be able to use the energy. But I don’t quite know if this is the correct way of doing it.
This is the module I’ve ordered:
And my idea was to create a board with 4 diodes and a capacitator in the end to get a good DC. And the disks are supposed to be connected to this board.

thanks for answer in advance
 

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Alec_t

Joined Sep 17, 2013
14,214
Unfortunately, that module will need far more energy to run it than your piezo discs could possibly harvest :(.
 

Thread Starter

Momme

Joined Oct 27, 2023
13
Unfortunately, that module will need far more energy to run it than your piezo discs could possibly harvest :(.
I’m thinking of using 12 discs in a shoe an the whole idea is that you walk a Serrano amount at charge. Do you think it’s possible to generate enough to charge a small AA battery for example?
 

Audioguru again

Joined Oct 21, 2019
6,608
The current from your tiny piezo discs is so small that you will need thousands of them and make them all move the same way at the same time to get a small current to light one little LED.
The Temu module uses an input voltage and current MUCH higher than the little piezo discs you have.
Your rectified discs might take centuries to charge one AA battery.
 

Thread Starter

Momme

Joined Oct 27, 2023
13
The current from your tiny piezo discs is so small that you will need thousands of them and make them all move the same way at the same time to get a small current to light one little LED.
The Temu module uses an input voltage and current MUCH higher than the little piezo discs you have.
Your rectified discs might take centuries to charge one AA battery.
ohh is that so I originally watched this video, how is he able to charge etc? Could you explain to me what I’m missing?

 

Thread Starter

Momme

Joined Oct 27, 2023
13
You're missing the fact that a lot of U-tube videos are complete scams and intended as click-bait.
okay but I was thinking about one more thing could I possibly combine tinny solar cells with the disks to harvest any sort o energy that is big enough to use?
 

Audioguru again

Joined Oct 21, 2019
6,608
The fake video showed LEDs lighting continuously when the piezo was squeezed. Impossible, its tiny current is too small to light LEDs and it generates the tiny current only when it is moving, not when it has stopped moving.

The battery voltage showed 3.5V before charging with the piezos. It was not dead so it powered the module thing with no problem.
After charging with the piezos the battery showed only 3.9V which is far from a full charge.
 

Thread Starter

Momme

Joined Oct 27, 2023
13
The fake video showed LEDs lighting continuously when the piezo was squeezed. Impossible, its tiny current is too small to light LEDs and it generates the tiny current only when it is moving, not when it has stopped moving.

The battery voltage showed 3.5V before charging with the piezos. It was not dead so it powered the module thing with no problem.
After charging with the piezos the battery showed only 3.9V which is far from a full charge.
okay I understand but if I combine with small solar cells could I possibly charge the battery?
And can I calculate this somehow?
 

Thread Starter

Momme

Joined Oct 27, 2023
13
Each solar cell is 0.5V and its rated current is at noon in the tropics pointing directly at the sun.
The battery has its rated voltage and its rated mAh capacity.
But in theory, if I have 4 small solar cells and combine this with let's say 12 piezo disks I should be able to at least charge an AA battery?
 

Audioguru again

Joined Oct 21, 2019
6,608
A 1.4V Energizer AA Ni-MH battery has a capacity of 2300mAh.
The solar panel with 6 cells (3V) I showed produces a max current of 100mA or probably an average daily sunlight of 50mA. Then it will charge the battery in 2300/50= 46 sunlight hours (3.8 days for half the year). If you must boost the 3V to 5V then the current from the battery is 1.67 times higher and the charging will also b e 1.67 times longer which is 6.4 days of average yearly and daily sunlight.

12 piezo discs are useless to charge a battery.
 

MisterBill2

Joined Jan 23, 2018
17,790
There have been articles published in legitimate technical journals about different methods of recovering energy through piezo-electric means. First, the devices used are much larger than the piezo discs you have. AND power is proportional to size as well as mechanical energy input. One grand scheme described piezo generators embedded in interstate highway pavement , which the energy input would be quite a bit. Unfortunately it did not become even close to cost effective.
Solar cells are a much better choice, but even then it is mandatory to examine the actual numbers relating to power delivered versus are occupied versus cost and effort involved. Solar cell power generation is much more advanced and so there is a lot of accurate data to be studied. BUT not on the cartoon channel.
 

Audioguru again

Joined Oct 21, 2019
6,608
The fake video on the cartoon channel must have had a hidden battery and latch circuit. When the piezo was pressed then its very short duration pulse set the latch which turned on the LED then when the piezo was released it very short duration pulse reset the latch which turned off the LED.
 

k1ng 1337

Joined Sep 11, 2020
910
okay but I was thinking about one more thing could I possibly combine tinny solar cells with the disks to harvest any sort o energy that is big enough to use?
Use Faraday's law of induction to generate electricity. A good beginner project is passing a high strength magnet through a coil of wire attached to an LED to generate a pulse of light. Instead of an LED, you can charge a capacitor or even a battery with enough passes.

The principle is simple and is commonly viewed two ways which is describing the same phenomenon:

1) A changing magnetic field induces a current in wire.

2) A current through a wire has an associated magnetic field which in turn affects everything in the vicinity.

This means to generate electricity with copper wire and a magnet, you can rotate the magnet around the wire or rotate the wire around the magnet. More turns of wire will increase voltage as well as moving either the magnet or wire faster. You'll have to experiment to find out what kind of magnet works best for your design.

induced voltage = -(turns of wire) x (change in magnetic flux / change in time)
 
Last edited:

ThePanMan

Joined Mar 13, 2020
757
You're missing the fact that a lot of U-tube videos are complete scams and intended as click-bait.
I second this comment. The video is pure fiction. Fake. A lie to get clicks. The U-tuber gets paid for people watching his/her video. Enticing suckers to click on their feed only feeds their bank account.
But in theory,
In "THEORY" 1V with 0Ω = infinite current. Then there's reality. A 1 volt battery can only deliver so much current at any given instant in time. A dead short will not result in infinite current. Boy if that were true the energy problem would have been solved a long long time ago. Imagine a 1 volt battery feeding a dead short inside a boiler tank. Water boils, the steam spins a generator, and you get FREE ENERGY. There's no such thing as free energy. At least not within the realm of physics as it is currently understood to be. There's very very little chance some backyard or basement mechanic is going to invent perpetual motion.

If you're really serious about this project then go ahead and build it. You will be disappointed in the outcome. You'll have spent your money on a stockpile of stuff you'll likely never find another use for. I know. I stock old IC's that I'll never use. Besides, those old IC's? They're obsolete because there are newer and better IC's for whatever project I might have made out of those old chips.
 

ThePanMan

Joined Mar 13, 2020
757
To answer your question about how piezo's work: They work by changing state. Pressure causes a change and generates a tiny charge. If you exert mechanical pressure consistently for any duration of time - let's get stupid here - if you apply pressure to one side of the disk for 10 hours you will get a tiny charge for a mere millisecond or maybe a few milliseconds. The rest of the time nothing is happening. When you remove the pressure - again, nothing happens unless you spring it back to a neutral position. But going from one extreme to neutral only gives you half of its potential. You have to exert the same amount of pressure in the opposite direction to get the full benefit of the energy it can produce. But all that mechanical work and effort goes into milliseconds of energy. Count how many steps you take in one minute and you then know you don't get much. IF you step one step for every second, then in one minute you can (hopefully) produce 60mV per minute. One hour of continuous walking - and keep in mind this is just speculation - in one hour you can produce 360mV. ASSUMING this is in a perfect world. In this perfect world you'd have to walk for 2 hours 46 minutes and 40 seconds. And that's just for ONE HARVESTED VOLT. 5 volts? That'd take you nearly 14 hours of continuous walking.

Using capacitors? They leak voltage. What you generate will be fairly quickly lost. But the good news is walking is good for your health. But the evidence is in - watching YouTube is unhealthy for your brain. Books are your best option for learning.
 

nsaspook

Joined Aug 27, 2009
12,778
To answer your question about how piezo's work: They work by changing state. Pressure causes a change and generates a tiny charge. If you exert mechanical pressure consistently for any duration of time - let's get stupid here - if you apply pressure to one side of the disk for 10 hours you will get a tiny charge for a mere millisecond or maybe a few milliseconds. The rest of the time nothing is happening. When you remove the pressure - again, nothing happens unless you spring it back to a neutral position. But going from one extreme to neutral only gives you half of its potential. You have to exert the same amount of pressure in the opposite direction to get the full benefit of the energy it can produce. But all that mechanical work and effort goes into milliseconds of energy. Count how many steps you take in one minute and you then know you don't get much. IF you step one step for every second, then in one minute you can (hopefully) produce 60mV per minute. One hour of continuous walking - and keep in mind this is just speculation - in one hour you can produce 360mV. ASSUMING this is in a perfect world. In this perfect world you'd have to walk for 2 hours 46 minutes and 40 seconds. And that's just for ONE HARVESTED VOLT. 5 volts? That'd take you nearly 14 hours of continuous walking.

Using capacitors? They leak voltage. What you generate will be fairly quickly lost. But the good news is walking is good for your health. But the evidence is in - watching YouTube is unhealthy for your brain. Books are your best option for learning.
I hate when people say this because there are a hell of of lot of books that are total garbage.
Correction, Watching garbage on YouTube is unhealthy for your brain.

There is a hell of a lot of good stuff on YouTube for those that take the time to look.
https://www.youtube.com/channel/UCJ0yBou72Lz9fqeMXh9mkog
https://www.youtube.com/@mitocw/videos
https://www.youtube.com/@PhysicsExplainedVideos/videos
 
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