# Super Capacitor

Vendor's Description:

Description: Yes you read that correctly - 10Farad capacitor. This small cap can be charged up and then slowly dissapated running an entire system for hours. Combine two in series for 5F/5V. Do not over voltage or reverse polarize these capacitors.

Description: Yes you read that correctly - 10Farad capacitor. This small cap can be charged up and then slowly dissapated running an entire system for hours. Combine two in series for 5F/5V. Do not over voltage or reverse polarize these capacitors. (from Sparkfun)

Just as a reminder:

Capacitors in series get a total capacitance(Ctot) of:

(1/Ctot)=(1/C1)+(1/C2)+...+(1/Cn)   which is like saying   Ctot=[(1/C1)+(1/C2)+...+(1/Cn)]^-1

Capacitors in parallel get:

Ctot=C1+C2+...+Cn

The voltage rating is the max voltage it can take. (http://letsmakerobots.com/node/1988)

some formulae:

i=(f/R)*e^(-t/τ)

ΔV=f*e^(-t/τ)

where τ=R*C

and f is the potential difference of the capacitor at the beginning

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Waiting for delivery on a nice 30F cap to use as a power levelling and storage device in a planned solar powered weather station.

It's rated at 2.7V, so i have it sitting between the parallel solar array (2 panels :P) that puts out 1.V, and a pololu voltage boost that then steps 1.5 up to 5V, suitable for running logic and transmitters.

Well now that my mouth is dry and my jaw is back up, WOW! I want one! These would be great for little solare powered racers like the ones from Solarbotics!

The world's best motto: When all else fails, use a bigger hammer.

The problem with most small super caps is their low voltage. True you can put them in series but then you have to buy more of them. There are higher voltage ones about if you look for them. I used this one in Bot 08M. Car sound systems often have 1F or greater capacitors rated at around 14V. Some of them have fancy displays for pimping out your ride.
A quite small 1F, 2.5V cap:  http://www.solarbotics.com/products/cpag1.0f/
I have a capacitor thing I pulled out of the motor for the pump in my heater. it is 1uf and rated for 420V. any ideas for a use for it?
unless you plan on using a bot at 420 volts, that's pretty useless. 1uF isn't very much. Try looking for capacitors in old computer power supplies, they usually have massive ones, likes this 200v capacitor I took from on, rated at 680uF.
I received 3 from Sparkfun last month and I'm not sure what I'm going to do with them yet.  Whatever it is, it'll be pretty great! :)

I have a really stupid question...

Lets say you hook up batteries to this thing ti charge the capacitor. In theory can you then remove the batteries and let something run off of the charge in the capacitor until it is drained? Seems like a cheap option to recharable batteries... I need to dig into capacitors more to learn how to figure out which type/specs go with each use, but this seems feasable to me anyway.

As far as I understand, this is correct.  You can use this site to figure out how long it'll take to discharge:

http://www.cvs1.uklinux.net/cgi-bin/calculators/time_const.cgi

The resistance will be the resistance of the circuit plus any additional resister you add to slow the discharge.  Be sure to use owms law to calculate the Amps that it'll output as well.  You don't want to burn out your circuit.

uhm but what voltage will you have from it while it discharge?

let's say that i want to run an arduino board with those caps, how should i set it up ?