# I wonder if i can get enough energy from the piezoelectricity to charge a Mobile phone ?

Hey everyone :) my name is Basel , and Im a 16 years old guy , and im thinking of using piezoelectricity to charge an original mobile phone , and i want to know if i can do that , and if i can get enough energy ? im sorry because of my weak language because im an arab :D please help me :)

ShumaelH2 months ago

i am doing project using piezoelecteric charging phone or portable devices while walking its my final year project i want help i making circuit what thing and material i can use and inwhich quantity and if i cannot charge phone what other portable devices i can charge

kelseymh1 year ago
As has been pointed out, you need both voltage (higher voltage than the battery you want to charge) and current (which reverses the chemistry inside the battery, you can imagine it like "putting the electrons back") to charge a battery.

Piezoelectric transducers can produce voltage (which you can then use for signals), but they produce very little current, not enough to charge a battery on a reasonable time scale.

More practical for your application would be an inductive charger. Something to make a magnet move through a coil of wire rapidly, over and over and over, producing both current and voltage ("EMF").
2 months ago

we can do amplify the voltage from cell right???

2 months ago

Energy is the product of voltage and charge (current x time), and is a constant (conserved quantity). If you use a transformer to increase the voltage, then the current will be reduced proportionately such that the product of the two remains the same:

Suppose you have a 9V battery which can deliver up to 1 A. If you "amplify" the voltage to be 27V, then the maximum current you can get is 1/3 A. The time it takes to recharge something depends on the current -- lower current means more charging time.

bahmaro (author)  kelseymh1 year ago
But im thinking of putting a piezoelectric generator in a shoe so it can charge the phone with the weight of a normal human :)
1 year ago
There are projects like that in development, in particular for the U.S. military. From what I have read, they aren't using piezos (because you don't get very much force from walking), but rather inductive generation.

If you have found papers describing piezo-based walking generators, it would be really cool if you posted links. Thanks!
1 year ago
You wouldn't be able to put enough crystals in even a pair of shoes and create enough constant movement to generate the power needed to charge a phone.
frollard1 year ago
Physical dimensions of the required crystals aside (despite them being gigantic).

You want to charge a phone from walking energy.

Charging a phone costs about 2.5-5 watts of power. The US military did a study on the feasibility of extracting this much power from the gait of a walking solder to power battlefield equipment.
They found it caused a LOT of discomfort and medical problems by merely extracting a few watts from a very physically fit individual during marches.

It doesn't seem like much, but any energy you take from your walk is NOT FREE. Your body is very inefficient at turning energy into motion, and adding more load to the system isn't using up some of that waste, it's in fact making MORE load resulting in MORE waste. Your body has to produce it, and you are using after the inefficient part, so anything extracted is pulled at the low efficiency level.
steveastrouk1 year ago
Yes, its quite possible. Look for"piezoelectric energy harvesting" as your search topic.
FoolishSage1 year ago
Technically yes but practically no. There are a few discos which use piezo crystals in the floor to generate power (http://www.treehugger.com/culture/eco-club-wars-dancers-literally-light-up-rotterdams-watt-londons-club4climate.html) but you need allot of crystals and allot of movement to get any usable electricity out of it
mpilchfamily1 year ago
In short... no.

The voltage produced is high but there is almost no current. Not to mention it's an AC voltage. I would take so many piezo crystals to generate enough power to get the 5V @ 200+mA you would need to charge a phone. So many it would take a car driving is circles over them to keep the power flowing.