Flashlight Without Batteries--from the book, "Haywired"

In this project, you will make a flashlight that works without batteries. Even more amazing, you can recharge it in three minutes and it will run for more than 24 hours. Because the ultra capacitors can be recharged thousands of times, you may save the environment from ever receiving an old flashlight in the trash system.

This project is from my book Haywired

Click here to order a copy from the Chicago Review Press.

Parts List

(2) 220 farad capacitors, www.digikey.com, #589-1013-nd
Insulated wire, black and red
Solder
LED, high brightness, www.jameco.com, #217525
12" x 12" acrylic plastic sheet, 1/8" thick
Permanent marker
(2) C clamps
Epoxy
1/4" jack, Radio Shack, #374-280
Metallic tape
SPST rocker switch, Radio Shack, #275-693
Glue
Electrical Tape

Tools List

Wire cutters
Soldering Iron
Scoring knife (for plastic)
Single-hole paper punch
3-volt DC power supply--700 milliamp
Drill
1/4", 1/16", and 3/4" drill bits
Metal straightedge

Step 1: Put capacitors in series

First, solder a wire from the (+) on one capacitor to the (-) on the other capacitor.

Comments

[Schmidty16]

how long does it last

[MikeTheMaker]

It's good for an hour or so at reasonable brightness--but it will continue to produce light for 24 hours or more.

[Schmidty16]

cool man i like

[viswamtvs]

i tried it
very nice

[luxstar]

done.. Here is the link to the 2600 farad flashlight instructable:

http://www.instructables.com/id/2600-Farad-Capacitor-Flashlight/

[MikeTheMaker]

Anyone interested in supercapacitor projects should look at this--and follow the links to suppliers. Luxstar has pointed out the best price for big caps that I have heard of!

[luxstar]

I recently made a supercapacitor flashlight that requires no batteries. I charge it off of a 5 watt solar panel. The larger capacitors of this type are usally quite expensive but the $10.00 2600 farad capacitors are back for now (on home page of Goldmine-Elec plus others on boost cap page).
Here is the link plus the link to instructions, diagrams, and pictures of the flashlight.
http://s247.photobucket.com/albums/gg153/luxstar/
http://www.goldmine-elec.com/

[MikeTheMaker]

Great resource! Thanks for sharing.

[luxstar]

Working on adding the pictures

[BC-45]

How do you charge a capacitor that is rated at 350 farad 2.7 volts any one know cause i don't know is it's safe to charge it wiht a 15 volt power supply.

[D5quar3]

 Digikey stopped selling the ultra capacitors anywhere else I can find them

[EngineeringShock]

www.electroniclessons.com will take you to an ebay store that sells all sorts of them. DC-DC boosters as well.

[Kasaron]

Seems like this needs to be hooked up to an induction generator, to really make it an emergency flashlight.

Anyone know if I have to use an AC/DC rectifier to sort out the charge?

[EngineeringShock]

To charge this circuit using even a good DC crank would take a heck of a long time, and it would result in an extremely sore arm =s

[LazarusTree]

This circuit seems potentially very dangerous to me. I think there needs to be at least one diode between the voltage input and the capacitors to limit electron flow in one direction and with a voltage rating less than the capacitors.

On what you have here, if you reverse the voltage and/or exceed the voltage rating on the caps and this is a potential bomb that will send shards of plastic flying everywhere.

[EngineeringShock]

If his input voltage is 3VDC, then he's not going to over-charge the caps. I'd be more concerned for the input source with no limiting resistors in series with the caps. That's a good way of destroying your wall wart,

[shobanaelango]

Are you suggesting that in any circuits it is better to use a diode between the voltage source and the capacitors? if we should add diodes to prevent from any accidents in a circuit in what all conditions and with what all components should we do that? It would be very kind of you to reply me............

[MikeTheMaker]

If you choose to Use a diode, it should have a higher voltage rating than the capacitors and it should be able to handle as much current as your power supply provides. If you power supply has diodes on the output (and no capacitors beyond the diodes), then you probably don't need an additional diode. Although these capacitors store a lot of energy (for a capacitor), it's less energy than a "aaa" battery.

[BC-45]

So how is run time determined by ferrad like if i have a 100uF cap it will last less and if i use 100F it will last longer is these right?

[MikeTheMaker]

Yes, the larger the amount of farads, the longer it will last.

If you can determine the "ohm equivalent" of your load, then the formula, T=RC where T=time (in seconds), R= resistance in ohms and C=capacitance in farads; then T will be approximately how long your capacitors will supply some power to your load. For example, if your load is 1000 ohms and you are using a 1000 microfarad capacitor (1000 X .001 =1) then the power will last about 1 second. This is the reason that you need capacitors with farads (not microfarads) of capacity to power anything for very long.

[Claudio_MV]

Hi, can I make this work with 2 1000 microfarad 200wv capacitors?

[MikeTheMaker]

The capacitors I suggested (in series) are the equivalent of one hundred ten million microfarads--so your capacitors are about 1/10000 of the storage.

That being said, what you have will work--but only for a few seconds.

[alexanderm]

Great Instructable! Thank you for sharing it!
Hopefully, it inspires people to buy your book!

i couldn't help but to think how cool it would be to add some solar cells in that clear case, though!

[Waren-Neutron]

such a great idea or i called invention
it so easy and educational ha....

[spark light]

(removed by author or community request)

[skyhell2009]

Can i use only a 1F capacitors..??

[MikeTheMaker]

1 F will work for a few seconds--enough to experiment with.

[MikeTheMaker]

The suggested capacitors are 220 farad rather than microfarad.

[skyhell2009]

Why we have to use 2 of 220F capacitor in this circuit, not only use 1 capacitor..???

[spark light]

these capacitors are only rated for 2.5 volts, and the led needs more than that to illuminate.

[MikeTheMaker]

You need to use two in series so that the voltage rating will be higher than the voltage required by the white led.

One capacitor (usually rated around 2.2volts) will be damaged if you charge it to a high enough voltage (around 3.5 volts) to light the led.

[spark light]

Oops, sorry. I misread it. Anyway, the caps have been discontinued, and it is pretty hard to find alternatives.

[shobanaelango]

Thank u very much for your response..... I have been doing a project on the topic RPS. So I made one. The specifications for it is (0-12)V. Since it is of variable type I used a LM317 regulator for it. The problem is I'm getting an output voltage range from (1.4-12)V but i should get from (0-12)V. After browsing thro' the Internet i found that diodes can be used in the circuit for that purpose but still, i don't know where to connect the diodes in the circuit to get the result........ I'm looking forward to your reply...........

[ukcuf]

Am I missing something here or are you effectively halving your capacitance by putting them in series One on its own 220 F Two in parallel 440 F Two in series 110 F (in the instructable they're in series?)

[MikeTheMaker]

I'm going in series to boost the voltage--2.5 volts is not enough to operate a white led (unless you add some circuitry, which is certainly a reasonable--though more complex option). It's actually the same power delivery, because doubling the voltage results in 4 times as much power delivered to a fixed (ohm) load.

[arkho]

I don't think so brother, because this led light consumes very minimal power. You can even light up an old school red led with a 1k resistor without charging it.  On the other hand, laptop as we know consumes more power, given the motor in the hard drive, the fan for the CPU and not to mention the back light for the LCD. Now most laptops, especially the new ones has lithium in the battery where the charge is stored that's how it sustains the need for power. However about the lifespan of the battery, I would say that one year is the normal life span of a laptop battery. I should know, 'cause I work for a computer company. :-)

[nani2010]

hey those are only farad capacitors or micro farad.
i got only micro once plz reply that what i sould keep.

[trekman]

I see finding a 200 to 220 F cap is difficult and expensive. What are any substitutes? I don't know anything about how to figure anything out but there should be trade offs in charging time and how long the LED stays on for different size capacitors. Can anyone give some options? Maybe using 3 or 4 of a easier / cheeper cap to get. Gerat Instructable!

[KT Gadget]

Here is a site that does give out some decent size caps. These I saw from Popular Science used in an electric screwdriver that is charged by a usb. Doesn't do big-heavy projects but it is good for short ones.

Only downside to these is the max voltage going through all of them is 5V in series (so 2 max in series). Putting them in parallel pairs, however, you can probably come close to matching to this instructable.

[scratchr]

use a supercapacitor (http://en.wikipedia.org/wiki/Electric_double-layer_capacitor)