How can i store the energy from a piezoelectric element, into a 3,2v Li-on battery?

Thread Starter

Kenjitzu

Joined Apr 27, 2022
2
Hello, I want to build a piezoelectric energy harvester, that can store the energy whenever it it pushed, into a standard 3,2v Li-on battery.
This is a project where I want to build a powerbank, that charges itself in the shoe, through pressure onto a Piezoelectric element.

My problem right now, is that I want to temporarily store the voltage into a Supercapacitor, so I can slowly charge it up to 3,6v, and afterwards make it automatically discarge into the 3,2v battery, until the supercapacitor reaches 3,2v and stops until it reaches 3,6v again from the piezoelectric element.

This process should be autonomous, but due to my lack of knowledge in the field, I'd like to know if anyone here would be willing to help me out with making this project a realization!

I've attached a simple diagram of what I currently think, the system should look like.
 

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Ya’akov

Joined Jan 27, 2019
5,657
Welcome to AAC.

Unfortunately, practical energy harvesting applications are much more complex than your proposal. Take a look at the datasheet for Analog Devices LTC3330 which is designed to do that job. Some complication in this case is because the IC can manage a variety of inputs, but piezos are among them.

The current you will get from the piezo is very small and the voltages are fairly high. Getting useful power from it takes a lot of work.

[EDIT: misfired on the submit button]
 

Thread Starter

Kenjitzu

Joined Apr 27, 2022
2
Welcome to AAC.

Unfortunately, practical energy harvesting applications are much more complex than your proposal. Take a look at the datasheet for Analog Devices LTC3330 which is designed to do that job. Some complication in this case is because the IC can manage a variety of inputs, but piezos are among them.

The current you will get from the piezo is very small and the voltages are fairly high. Getting useful power from it takes a lot of work.

[EDIT: misfired on the submit button]
Thanks for the quick response!
I have a plan B for this very same project, involving a linear induction generator, where a magnet swings forwards and backwards inside a tube with copper coils wrapped around the outside of the tube, do you think the current here would be high enough to attain my goals?
 

Ya’akov

Joined Jan 27, 2019
5,657
Thanks for the quick response!
I have a plan B for this very same project, involving a linear induction generator, where a magnet swings forwards and backwards inside a tube with copper coils wrapped around the outside of the tube, do you think the current here would be high enough to attain my goals?
That method is used in the "Shake Light" flash light. You have to use a rectifier, of course which will drop the voltage. You could make the rectifier from Schottky diodes to reduce the drop. if you want to charge a battery, using the supercap as an accumulator is a good idea, but you will have to prevent it from discharging until the voltage is sufficient to actually charge the battery. Doing this in a low power way might be tricky.

I wonder if anyone here has an idea for a clever circuit to do this. I have a vague idea of using a zener diode and an SCR but I don't know how much loss the would entail, or if the SCR would turn off at the right time.
 

Audioguru again

Joined Oct 21, 2019
4,674
Back to the piezo in a shoe energy harvester:
How many years will it be harvesting the tiny current to charge a little battery when you will never stop walking on the piezo in a shoe? Look in Google, students have already done it.
 
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