charging a single NiMH aaa battery from a supercapacitor

[jeromekang]

hi i want to charge a single NiMH aaa battery. So the flow of the circuit that i am thinking of looks like:

piezo transducer -> ac to dc -> supercapacitor -> battery

so my question is... can the supercapacitor be connected in parallel with the battery to charge it? the supercapacitor is 10F 2.3V and the battery is 1.5V.

 

[FvM]

The only meaningful reason to use a Supercap as intermediate energy storage would be an input current above the rated charge current of the battery. I doubt that this is the case with a piezo transducer.

 

[jeromekang]

correct me if i am wrong..so what you are saying is that i can directly charge the batteries without the supercap? what if i used an ordinary electrolytic capacitor?

 

[karesz]

Hi Jerome,
I think, you can read much interesting sides over your problem & solutions here: https://www.ioxus.com/applications.html]

Design-Aid Calculators: **broken link removed**
K.

 

[Audioguru]

The energy output from a piezo transducer is so small that it will take weeks or months to charge an AAA Ni-MH cell. Then the piezo transducer will fracture from fatigue.

Are you the guy on the other website who is trying to harvest the energy from a piezo BBQ lighter?
It might fail after a few hundred clicks. You might need millions of clicks to charge an AAA Ni-MH cell.

 

[karesz]

Hi Audioguru,
I can not agree with the cracks aspect;
if you will try properly dimensioning_it will work over many moths, but these is not a simple job!
We can find lot of dissertations over that_ I believe, its not a random effect, its really complex subject.
K.

 

[FvM]

The piezo BBQ lighter example clarifies, that it's necessary to thing about utilizable mechanical power and impedance matching.
Without elementary mechanical and electrical engineering knowledge, the case is - hopeless.

 

[Audioguru]

You can buy a very expensive "energy harvesting" IC. Its max allowed input is 500V but a piezo BBQ lighter has an output of thousands of volts.

They do not show how to reduce the voltage without wasting a lot of the tiny amount of power.
The energy harvesting IC efficiently reduces the 500V down to a few volts. Maybe a watch can be powered.

 

[jeromekang]

@Audioguru no i'm not the guy on the other website

@karesz thanks for the links appreciate it