mobilephone charging using piezo electric crystal

[narayanan]

hi i like to do an project on automatic mobilephone charging using piezoelectric crystal ... small piezoelectric crystal are placed beneath the keypad and when the user types the keypad it generate electric current which is given to the mobilephone battery

I like to know whether it is possible to do this ...or there gonna be any reverse effect due to this ... plzzzz help me out with this ...this is my final year project so plz help me

 

[MikeMl]

Have you researched how much power is generated when a piezo is bent? You just failed your class!

 

[narayanan]

when i pressed the quartz crystal i got 1147mV as the meter reading ....its a low quality crystal.... i hav started my project just now ...want to know whether it will work or not ....plz help me out...

 

[schmitt trigger]

1147mV with what amount of current? You need to know the available current also.

 

[Vizier87]

A piezo transducer sometimes generate very high voltage (like the ones you see in electronic lighters, it is piezo-generated) but I doubt it can be used to charge batteries. It's too unstable.

Use something else.

 

[MikeMl]

when i pressed the quartz crystal i got 1147mV as the meter reading ...

But have you determined how much POWER (Voltage X Current) it makes????

 

[KMoffett]

A piezo transducer sometimes generate very high voltage (like the ones you see in electronic lighters, it is piezo-generated)

Remember how much force you have to apply to those igniter module buttons. Can you imagine having to do that with each keystroke on you cell phone. It would certainly result in even more abbreviated twitter messages.

Ken

 

[Sceadwian]

Something like this is currently being toyed with to try to draw power from people stepping on special tiles, but even those are just barely able to actualyl provide useful power and are incredibly expensive, I'm not even sure if they're piezo based. Totally impractical on a small scale like a cell phone though. It could possible work for something as large as a full scale keyboard if someone typed all the time, but even then the amount of energy available is incredibly small, especially with the horrible efficiencies involved in converting it.

 

[arunb]

piezo transducer sometimes generate very high voltage

I am just curious here ...so why can't can the voltage be used to charge a battery ??

how much voltage is generated ?? must be very high as a spark is generated between the electrodes, like a lightning bolt ??

 

[Vizier87]

The idea of charging is that it comes from a continuous and stable source. Like solar, although it varies its output, the changes are gradual and processable using current/voltage converters to compensate the changes.

A piezo depends on displacements which changes the capacitance, results in voltage spikes.

An analogy would be useful:
Imagine trying to massage a friend using a hammer. You can make the poor fella some reservations to the hospital. Your friend would still get his massage though.

Might as well tell the government to store the energy we get from lightning strikes!

 

[arunb]

I got that clear now...thanks for that

So is solar energy really 'usable'.....??

Although Solar panels have become quite efficient over the years, but are they a practical solution to say powering a house ??

 

[transistor495]

Nowadays we're charging our mobile batteries at a rate of around 500mAh for 3hours(depends of course!). The current produced by the tiny piezo crystals hidden under the keypad may be something at a high voltage that is enough for nothing!

A fairly impossible idea in my opinion.

For your information SAMSUNG E1107 is a solar powered phone that delivers 10mins of talktime if you get 1hour sun tanned. Go for it

Wind-up chargers are there for emergency purposes.

I can't believe how you got this project approved?

 

[Nigel Goodwin]

I can't believe how you got this project approved?

I can't believe a final year student would know so little?.

 

[KMoffett]

Actually, there is some science behind narayana's original concept. Google: piezo energy harvesting.

Ken

 

[ch102]

Nigel/transistor

Has ken metioned pls google or read Piezoelectric Energy Harvesting Kit before commenting how he got his project approved.

 

[Sceadwian]

I already mentioned something liek that KMoffett.
However the physical impact from the keystroke of a mobile device doesn't have even remotly close to enough harvestable energy to be even a consideration. only high energy impacts are even possibly a source for useful ammounts of power. You could possibly do something electromehcanical on a keyboard with a long throw, where the energy could be derived from a spring effect rather than shock based like a piezo, agai however at that point that device is already wires so it's poinltess to try to draw that energy off because it's so low. Before anything like that can become feasable device energy usage has to drop at least an order of magnitude or more.

 

[tcmtech]

So have they completely stopped giving physics classes now for college educations?

In high school we had basic energy and power level understandings. bacteria to flea to human to power plant to wind, to planet, to sun. Orders of a million give or take.
You guys ever get that one in high school?

 

[audioguru]

I think he didn't go to school. Maybe in his country there are no schools.

 

[ke5frf]

You might do better coming up with a kinetic motion generator. Watches have been doing it for a while now. In principal not unlike the older self-winding technology.

I doubt the power needed would be feasible within the size limitations of the modern PDA or flip phone. We are too spoiled to small and lightweight. But perhaps a two battery system could be fabricated with the generator warn as a clothing accessory...a belt pack, an arm band, attached to the inside of a jacket lining with buttons or zippers, etc.

The user could swap batteries when the in-use one loses its charge.

Probably wouldn't fly as a commercial product. Just as easy to plug spare batteries into a wall charger. But the concept probably is feasible and might be good for a college project.

 

[arunb]

I think he didn't go to school. Maybe in his country there are no schools.

That is not helpful....

Just because someone thinks 'out of the box', you do not have to insult him..I agree criticism is essential, but it should not be personal..