Fun with supercapacitor: an usb rechargeable LED flashlight

So it was a long time since i wanted to play with a supercapacitor. I found a good deal on ebay for some 4F, 5.5V capacitor.

The first thing i made is a micro flashlight. It's basically a single super bright (i think 10k mcd) LED with a 660 resistor, a custom USB plug for recharging, and a small switch to turn it on and off.

I made this to see how much juice these supercapacitors could hold. Well, the final result is: a lot :) Powering it for a two or three minutes will keep the led at good brightness for a couple of hours, after that it starts to fade but it's still "light" for more hours, gettin dimmer and dimmer :)

It turns out it's quite a useful flashlight :) with the usb port it can be recharged almost anywhere, the capacitor doesn't have memory effect or loss of capacity over time like batteries, so it's just "plug" at any time without worrying and use it :P

All considered, a funny project :)

HgU7n.jpg

image:

image:

Do you limit the charging

Do you limit the charging current?

absolutely not, the

absolutely not, the capacitor is connected directly to the usb port

italians light it better

italians light it better :stuck_out_tongue:

have you the opportunity to test your supercap with a pager motor? do you think that is suitable for power a small robot?
can you provide infos about charge and discharge current of your cap?

LOL :Pthe specification are

LOL :stuck_out_tongue:

the specification are these (i’m not good enought to understand all  :stuck_out_tongue: ):

Specifications:

Rated voltage: 5.5V

Rated discharge capacitance: 4F

ESR (mΩ, 1KHz, 25) : 120

DC Imp (mΩ, 0.1A, 25) : 180

Work temperature range: -25 to 70 Degree Celsius

Storage temperature range: -40 to 85 Degree Celsius

weight: 6.8g

Size (ΦDL): 24.96 mm

Pin configuration: vertical

Long life time : more than 100, 000 times

Maintenance-free operation

Environment-friendly, RoHS compliant

I haven’t tryed with a motor yet, but i’ve tryied to power an arduino with a buzzer and it worked. I don’t know for how long :slight_smile:

ok thankyouDC Imp (mΩ,

ok thankyou

DC Imp (mΩ, 0.1A, 25) : 180

this wah the parameter i was searching for. I think it’s ok to drive a small motor

care to explain what does it

care to explain what does it mean ? :slight_smile:

Great idea! Could you please

Great idea! Could you please make a schematic of your setup? Thanks

** big capacitors have big**

 

big capacitors have big equivalent series resistance compared to standard capacitors

this is an issue because it limit the max current that the cap can supply

 

 

So it charges almost

So it charges almost instantly (a few ms)? Nice :) 

Cool idea!

Very cool thing, the usb charching function is very handy. I would like to make a similair thing. But then

something that charges itself with a solarpanel. Wouldn’t that be a great idea?