Looking for capacitors, Please Help

[nightstalker101]

I am going to attempt to make a 300watt Maglite. I plan on doing this with a capacitor or multiple capacitors. I figured out the math today, and to get a 300watt 200volt bulb to light for 3 seconds to "1/e"(1/3) the output I would need a 200volt capacitor that could hold 22.6mF, I would also have a 133ohm resister. Now I am wondering where I can find a capaciter close to this size that is skinny engough to fit in a D sized light. Also if you see an errors in this, or reasons why it wouldn't work I would love the hear them, thank you.

 

[naga]

impossible hahah

for starters 300watts for 3 seconds means 900 Joules. To achieve this energy storage would require capacitors that would be the size of 6 coke cans.

I don't think u would put a resistor in there either would be wasting energy. The bulb would be ur resistor.

good luck trying anyway

 

[scott.cr]

I don't know if this will hold the energy you are looking for, but I'm sure someone here can help you with the math.

p/n P11349-ND on digikey.com... it's a Panasonic "Gold Cap." 70 Farads of capacity @ 2.1v.

Digikey carries other voltages and ratings too...

 

[nightstalker101]

I don't know if this will hold the energy you are looking for, but I'm sure someone here can help you with the math.

p/n P11349-ND on digikey.com... it's a Panasonic "Gold Cap." 70 Farads of capacity @ 2.1v.

Digikey carries other voltages and ratings too...

Thanks, this would actually probably work, however I wonder if it is actually 70 Farads and not 70mFarads or 70uFarads. If anyone knows that would be great.

 

[ckthorp]

Thanks, this would actually probably work, however I wonder if it is actually 70 Farads and not 70mFarads or 70uFarads. If anyone knows that would be great.

I think you might have better luck with A123 system's 26650 LiIon cells. They'll take something crazy like 50A discharge. At maybe 3v under heavy load, you'd only need two of those to get to 300w of burst usage.

 

[matrixshaman]

Hmmmm... First do you have a 200 volt 300 watt bulb? If not what were you going to use that is 200 volts at 300 watts? This sounds more like a slow burst camera flash. Maybe a big reflector and some gunpowder would be cheaper - that's essentially what they used to use in photography. Or maybe you are just looking for that firestarter function from a light like in the video I'm sure everyone has seen? Sorry for the sarcasm but it just seems like a very unusual project with little use. But let us know as I don't want to discourage any free thinking. Another question - what would you use to charge this to 200 volts? That kind of voltage can be dangerous in a capacitor - especially if there are enough farads to light a 300 watt bulb. Be careful with this project.

 

[nightstalker101]

Hmmmm... First do you have a 200 volt 300 watt bulb? If not what were you going to use that is 200 volts at 300 watts? This sounds more like a slow burst camera flash. Maybe a big reflector and some gunpowder would be cheaper - that's essentially what they used to use in photography. Or maybe you are just looking for that firestarter function from a light like in the video I'm sure everyone has seen? Sorry for the sarcasm but it just seems like a very unusual project with little use. But let us know as I don't want to discourage any free thinking. Another question - what would you use to charge this to 200 volts? That kind of voltage can be dangerous in a capacitor - especially if there are enough farads to light a 300 watt bulb. Be careful with this project.

Well, I already have a ROP L/E and I have a 2C with a 5761 bulb. Now I would want to increase my brightness alot but still keep it within a 3D size. However I don't want to spend alot of money and I was thinking the capacitor would be rather cheep. I am still working on the 200v power source, I still have a lot of looking to do, lol. This would mainly be a "WOW" light. Like I said, I don't want to spend a lot of money (less than $75) and still get something insainly bright (+100Watt). So I'm not sure yet.

 

[nightstalker101]

I think you might have better luck with A123 system's 26650 LiIon cells. They'll take something crazy like 50A discharge. At maybe 3v under heavy load, you'd only need two of those to get to 300w of burst usage.

Does anyone know where to find these?

 

[matrixshaman]

There's a web site for them but not sure how readily available they are. www.a123systems.com is the site I believe - just went there and it's freaking my browser but I've seen their site before from another thread here. IIRC the only application currently available to the general public using their batteries is a DeWalt 36 volt battery for power tools and it's been going for around $200.

 

[nightstalker101]

Does anyone know what the cheapest 100+ Watt Maglite would be?

 

[ckthorp]

There's a web site for them but not sure how readily available they are. www.a123systems.com is the site I believe - just went there and it's freaking my browser but I've seen their site before from another thread here. IIRC the only application currently available to the general public using their batteries is a DeWalt 36 volt battery for power tools and it's been going for around $200.

You can get the batteries for $115+S&H here: http://cgi.ebay.com/DeWalt-36-Volt-...3QQihZ014QQcategoryZ82272QQrdZ1QQcmdZViewItem so they can be had for well under $200. That nets you quite a number of cells.

 

[zamboniman]

The capacitors are indeed 70 farads -- google "carbon aerogel capacitor" or "electrochemical double-layer capacitor". You'd need 100 of them in series, though, and supercaps tend to have a high enough internal resistance that they can only put out something like 10 amps. Personally, I'd just recommend 4 50 watt 12v halogen bulbs hooked to a car battery. You could get about 1.5 hours runtime.

 

[2xTrinity]

One point worthy of not: While the nominal voltage number for a battery represents typical operating voltage, In the case of a capacitor, the nominal voltage is actaully the maximum voltage it will tolerate. The real voltage will be less than that, and will constantly drop all the way to zero as you discharge it. Unless you have a regulator circuit that can operate across a 0-200v range, a very large portion of the energy stored in your capacitor will be useless for driving a bulb. (capacitors are better for driving a Xenon flashlamp, like the one in your camera, than an incan bulb)


For a high power incan "burst" light, the A123 LiIon batteries are your best bet, those are designed for short bursts of acceleration and regenerative charging in electric vehicles, so they're perfectly suited to your application. A pack of them should be able to drive a 300W lamp for a couple minutes, and the plus is, you can rechrage and reuse them again in only several minutes charging time (you might want some kind of fan cooling with that kind of turnaround time though...)

 

[Data]

I have over 150 of the A123 cells (I got them for my electric dirt bike project). You can buy them directly from a123systems but only in their prototype kit that is very expensive. The best place to get them is from DeWalt packs, as was mentioned before. See this web site > http://www.slkelectronics.com/DeWalt/index.htm

They are a very "safe", "C" size battery, about 2.5" long, that will source over 70A continuous. There is a good charger on the market made to charge them too.

Cheers
Dave