# charging a li po battery through piezoelectric crytals while using it

Me and my friends are working on a project that requires a pretty long battery life. but since we can't fit any battery powerful enough in the project, we had to use a smaller one, but now, we have to charge it through piezoelectric crystals. Is this possible, if yes is there a board I can use for it.

I will be using: -3.7 V 600 mAH li po battery -10 piezoelectric generators in parallel. they each create 0.4 V

Regards, Yigit

Which piezoelectric generators will you be using?

Note that they need to be connected in series, if the voltages are to add.

Solar cells are easy to use.

I will be using those

I am connecting them in parallel because apparently, It doesn't create enough current

No you would need them in series because 0.4V is not enough to charge a lipo which is 4.2V fully charged. then if you need more current you'd need parallel sets which means at least 100 elements. And those basic piezo elements produce AC not DC and only intermittently which isn't much use. Even if you convert it to DC charging lipos without using a proper CC/CV charger is a dangerous trick.

I think you'd do better to see if it's possible to reduce the energy used by your "project" as an alternative way to extend battery life.

Steve

Those piezo disks will work as microphones or buzzers, but won't be useful to charge batteries.

If you want to learn about piezoelectric energy harvesting, here is one place to start.

-10 piezoelectric generators in parallel. they each create 0.4 V

Do you have any idea how much current you're getting? (Of course, you'll get less current when you re-wire the piezos in series to get 4V.)

What's "powering" the piezos? There's probably a more efficient way to capture/convert that energy.

Have you made any energy calculations/estimates? i.e. If you could get 1mA continuously (which is probably optimistic) and if you could get 100% charging-efficiency (which is optimistic ) it would take 600 hours to fully-charge a dead battery. And, that's assuming (optimistically) the battery isn't being used/drained while it's charging.

Hi, What is your project that needs this charging arrangement.

From your understanding of current and voltage, there may be a way to reduce your power needs for a start.

How will you be getting the "Piezo Generators" to generate any power?

Tom... :)

Whats going to be vibrating the crystals and how much force will be applied? This is what determines how much useful power can be made.

I will be using those

That's not how to design something - you figure out the power requirements first, then pick a device that is capable of providing it.

Choosing a device first is most likely to completely fail.

Start again by telling us much more about your project and how its powered, the various devices that consume power