Piezoelectric Transducer Help

[MrJesterMD]

Ok, total noob here. I should also mention I know practically nothing about electronics so please have patience with me. I have an idea for invention (please don't ask what, I don't have a patent yet) in which part of it involves charging a li-ion battery with a thin film piezoelectric transducer. My question is basically, how? As I understand it, the battery would require a certain amount of volts in order to accept a charge. Since piezo transducers fluctuate volts according to pressure, how do I get constant volts to the battery? I'm thinking it would need a capacitor and/or a resistor. But like I mentioned previously, I know very little. Thanks in advance for your help.

-Jesse

 

[KrisBlueNZ]

Hi Jesse and welcome to Electronics Point

Unless you have an industrial piezo and you're pounding it with a sledgehammer thousands of times per second, you won't get enough power to overcome the battery's own self-discharge, let alone charge it to any useful voltage in any reasonable period of time. You would be better off using a pedal-operated generator that you crank with your little toe once a week.

Energy is energy, true enough, and energy can be converted between different forms. The common physics noob mistakes are to overestimate the efficiency of these conversions (solar cells and loudspeakers are less than 10% efficient, for example) and more commonly, to misjudge the scale of the energy available from different sources.

Here are some examples. The amount of energy needed to heat a room for one day is around a thousand times the amount of energy needed to charge a cellphone. And that's around a thousand times the amount of energy needed to make your headphones run at deafening volume for an hour. And that's over a thousand times the amount of energy you can get from many "energy harvesting" sources. I don't know where the piezoelectric transducer fits in there, but it's near the low end as well.

 

[OLIVE2222]

Dedicated semiconductors are already marketed to do that, here under a (piezo filtered) selection of the linear technology range:

http://www.linear.com/parametric/En...,1646,1033,1032!s_0,0!gtd_!2200_Piezoelectric

 

[MrJesterMD]

Thanks guys.

Kris, I definitely appreciate your input but I'm not gonna give up just yet.
OLIVE, thanks I'll look into the link you suggested.

If I figure something out, I'll most likely be back with further questions. I'm glad I found this place.
Thanks again

-Jesse