super capacitor capacity?

[Divedeep]

I know that the cr2032 can last for between 6 and 9 months. Using a battery is easy. I like to see how far i can push things. After all a device with no battery would be quite good, dont you think??

So Adam, is that 100 odd amps divded by turns In the coil. So a coil with 100 turns would be around 1 amp. ??

 

[BobK]

Or, perhaps he did not know that that was all that was needed. That is why I posted. It also gives a good example of how much superior batteries are to supercapacitors in energy / volume density.

Bob

 

[flippineck]

In the charging circuit could one arrange things somehow, such that the electromagnetic output from the transmitter coil is focussed toward the receiver coil, to counter the inverse square law, some kind of simple parabolic reflector or something?

 

[Ratch]

Hi.

I am working on a project and have had an idea to improve it. There are 2 parts to this improvement.

First I would like to replace the battery in the device for a super capacitor. I have seen 10F , 2.7v capacitors available.

The device itself runs on around 2-5uA when asleep. When awake draw is aroun 15-30mA. The device is awake for 1 second every 15 minutes.

My question is how much power can the capacitor hold and how long could it power my device?

A capacitor stores energy, not power. I got 14.5 hours, which agrees with what Kris calculated.

The second part i would like to have a go at is charging the device by wireless energy transfer.
I am wondering if it is possible to transfer enough energy to keep the capacitor charged so power is available when required.

The transmitter for the wireless power transfer will be around 3-4 meters from the device to be powered.

Thanks

 

[Ratch]

Thank you.

This is a bit new to me as i havnt used a capacitor to powet a device before. It seems they work pretty much like a battery but over a shorter period.

No, a battery's energy is stored chemically. A capacitor's energy is stored in its electrostatic field.

I also guess that they have a power curve much like that of a battery?

Their deenergizing curves are completely different.

The difference i can see with a capacitor is they can be drained to 0v.

They can both be shorted for no good reason.

Ratch