Hi,

Can anyone help me please with the necessary calculations and materials needed for harvesting piezoelectric energy?

Here where I am stuck up

If one disc can generate around .200 V, how can it charge a battery?

I am trying to line up 350 discs as a step board for my thesis and I am stuck to where should I ask my questions

Please help.

 

Hi Nagar,
Welcome to AAC.
Is this homework or a college assignment?

Moderation.

 

If one disc can generate around .200 V, how can it charge a battery?

I suggest you do some research to find out how much current a piezoelectric disc can provide.
Welcome to AAC!

 

Before you can solve this, you need to understand the problem.

The answer lies in the idea of matching the properties of the generator to the properties of the load.
As well, understanding the levels of power involved at all stages.

 

I see a rather daunting challenge in the application of anything close to a uniform force to 350 piezoelectric discs.
Certainly it is an original thesis topic, being an energy harvesting application there may be a fair amount of published information, though.
While certainly there may be a rather high voltage generated, I suggest an analysis of the power in that wave form. It is a quite narrow spike, so while the voltage may be great the power is not very large. So it might be that a thesis developing explanations of why a concept does not work may be a more valuable creation and a great public service.

I recall an article several years ago about the invention of a piezoelectric sidewalk that was intended to provide energy for some purpose. The short analysis was that, given that energy out must come from energy in, that the general public would learn to avoid the section of sidewalk that required more work (=energy) to traverse.
Also, there is the durability issue, as was discussed relative to the concept of piezoelectric roadway sections to provide battery charging for roadway sign illumination.

 

The noise from thousands of cattle running on the piezo discs might produce more current than the tiny power from the piezos.

 

The noise from thousands of cattle running on the piezo discs might produce more current than the tiny power from the piezos.

Burning the dry cow flops would generate even more energy.

 

My point, back in post #5, is that wishful thinking does not provide the data required for an accurate evaluation of a concept. Of course, doing an analysis based on guesses and estimates and a common consensus is not likely to produce any better results.
Regarding the question about how can the 200 volt pulses charge a battery, the answer is that first the power must be collected, often by charging a capacitor. Then the collected energy must be converted to the voltage that is useful for charging the selected battery. Collecting the energy may not be difficult, but the efficient conversion to the correct voltage is not a trivial matter, because often it requires some form of switch-mode circuit, which is not a trivial task.
For the initial concept of 350 piezo discs, even the means of collecting all of that pulse energy is a challenge. Unless the mechanical portion is perfectly timed, the requirement will be quite a challenge.
As for the initial calculations, I suggest assuming 100% efficiency so that power out equals power in. That will provide a starting point, at least.

 

My point, back in post #5, is that wishful thinking does not provide the data required for an accurate evaluation of a concept. Of course, doing an analysis based on guesses and estimates and a common consensus is not likely to produce any better results.

In my very short life, I've seen low yield energy harvesting ideas investigated and tried over and over with the same results. There must be a stack of papers (old school real paper) a mile high with the same results.
It's a good learning exercise to do it but don't expect a different result.

“I canna’ change the laws of physics, Captain! –SCOTTY, CHIEF ENGINEER IN STAR TREK”

 

I suggest you do some research to find out how much current a piezoelectric disc can provide.
Welcome to AAC!

Yes, I would start there. Bang a piezo crystal and you see open circuit voltage. This looks fine right till we place a load across our piezo disc.

Ron

 

That was my early suggestion Still valid, although a bit difficult.

 

That was my early suggestion Still valid, although a bit difficult.

When I was maybe 10 or 11 years old cars had generators. I discovered that if I just applied power to a generator it ran like a motor. This was nothing short of a major discovery. I brought this up to my father who said go for it. I managed to tie two old generators to a board. I am on the verge of perpetual motion and a gain over unity. I would visit gas stations and buy for about 50 cents old car batteries with a bad cell or two. My mother was wondering why my pants and shirts came out of the wash with holes. I was also learning about battery acid.

Now my father could have spared me the disappointment that my discovery was an epic failure but he liked it when I discovered things on my own. See where this is going?

Ron

 

When I was maybe 10 or 11 years old cars had generators. I discovered that if I just applied power to a generator it ran like a motor. This was nothing short of a major discovery. I brought this up to my father who said go for it. I managed to tie two old generators to a board. I am on the verge of perpetual motion and a gain over unity. I would visit gas stations and buy for about 50 cents old car batteries with a bad cell or two. My mother was wondering why my pants and shirts came out of the wash with holes. I was also learning about battery acid.

Now my father could have spared me the disappointment that my discovery was an epic failure but he liked it when I discovered things on my own. See where this is going?

Ron

I had much the same experience but I learned that polyester doesn't get battery acid burns but it does have that cool flaming drip burn.

 

WOW!! now tye deposit on old batteries is typically $10, so they are all recycled, and never found in dumps. I used 120 volt AC motors, no batteries and the rid was only the length of the power cord. And it was explained at a very early time in my experimenting that the wasted energy was what produced the heat that I felt in just about every electrical device. So no perpetual motion dreams, except capturing wave energy. Which is difficult to do efficiently on any useful scale, by the way. Then I discovered the beauty os a gasoline engine. Unlimited power, and the big cost was financing getting things welded to assemble fast vehicles. Long before drivers license age.

 

If you have the engineer knack then the perpetual motion dream as a kid is normal and expected. It's like that first girl that breaks your heart, you get over it, by finding another toy to play with.

 

I haven't read this, but it might be useful.
A comprehensive review on the state-of-the-art of piezoelectric energy harvesting

 

I haven't read this, but it might be useful.
A comprehensive review on the state-of-the-art of piezoelectric energy harvesting

Informative. That hill of papers is getting pretty tall.

Fig. 1. Number of documents on “piezoelectric energy harvesting” by year (all data from Scopus).

 

Informative. That hill of papers is getting pretty tall.
View attachment 316370
Fig. 1. Number of documents on “piezoelectric energy harvesting” by year (all data from Scopus).

Did you count all of them yourself?

 

Did you count all of them yourself?

I asked my normal expert on all matters.