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Ultracapacitors have come a long way, and still going..

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The trouble with caps is of course that they don't put out power at just one voltage. If you try to run a device that only works from 13v to 10v you're only using 40% of its capacity. Given, you'll only need to return 40% to get it back up, but we paid a lot for that capacity. The bad part is that the device's performance is often variable over that range.

The cool part is by putting on a dc/dc coverter you can make the output voltage constant despite the input voltage and, if it's a boost converter, you can drain the entire capacity of the caps to 0v before the output shuts off. Makes real good use of even a single ultracap. Best idea is a buck-boost converter.

With a boost converter, a 1W Luxeon would go for 2.6 hrs off a single 2600F 2.7v ultracap (in theory only, 10%-15% losses should be anticipated in the converter). 350F, 0.35 hr. Unfortunately powered the converter may be tricky but you get the idea.
 
Yes ! and one of the coolest parts is that it could charge up in a second if i could supply that much current.
conversly it can discharge all its energy in a split second ..
Energy = .5CV^2 = 1/2( 110)(2.5)^2 = 343.75 Jouls
I imagine that it could damage a semiconductor voltage regulator?
 
well it could take up a surplus of generated current in a system that has peaks both in exess and deficiency. for exanple a generating system that supplys from 0.5-2 amps can use it to charge at 1 amp. the eccess being held in the cap and given to the battery in a generator shortage :wink:
 
If you search ebay for" digital farad capacitor
or google " ebay digital farad capacitor
there are tons of people selling 12V ultra caps for car stereo systems.
they range in size from .5F to 6 Farad..
but shipping costs an arn & a leg

this is a link to some of them
**broken link removed**
and check the ESR rating , it should be around 0.001 ohms
 
i just thought of using one of those 12 V ultra caps on my solar array? not really an array , just two collectors ..
anyway i could put one on there soaking up power all day , and when i put my NiMH rechargables on there , BAM a day or night charger..
 
:shock: Those ultra caps R amazin :shock: over here in Oz the biggest I've seen is a 1 farad cap which sells for around $100. But looking at that link Willi put up there's a 5 farad cap for the same price :cry: an man 25 farad caps for $139 US :twisted: I WANT ONE WAAAAAAAA :twisted: but dey won't ship to Oz :cry:
 
Wow those things are AMAZING!! If you put enough of those in series to have a good enough voltage rating, they would make one heckuva coil gun :twisted:
 
williB said:
lol yes it would .
could you imagine dumping all that current into an unsuspecting coil lol..
I like the way you worded that, hee hee hee :lol:

I'd really like to do that, only problem is I'll bet those things aren't cheap. Say I made someone electro's coil gun that uses 70V, I'd have to have a lot of the 2.5V ones in order to attain 70V and I'll bet that would be expensive. Not to mention that coil would probably vaporize :lol:
 
zachtheterrible said:
williB said:
lol yes it would .
could you imagine dumping all that current into an unsuspecting coil lol..
I like the way you worded that, hee hee hee :lol:

I'd really like to do that, only problem is I'll bet those things aren't cheap. Say I made someone electro's coil gun that uses 70V, I'd have to have a lot of the 2.5V ones in order to attain 70V and I'll bet that would be expensive. Not to mention that coil would probably vaporize :lol:
thats the best part .. a coil gun runs on current not voltage..
one , or two ( in parallel )would do it..
 
They have 56V modeules.

But you wod need an supercoductor coil to discharge such an big cap.

1000V shod do.
But you dont have a whode room full of caps :lol:
Not to methon the price.
 
Ahh you posted fater wiliB.

You need voltage to get the huge curent troung the coil.(Ohoms law)

You wod need any aray of smaller ones to get the low enugh resistance.
 
Someone Electro said:
Ahh you posted fater wiliB.

You need voltage to get the huge curent troung the coil.(Ohoms law)

You wod need any aray of smaller ones to get the low enugh resistance.
as for the resistance , is 0.003 low enough.??

essentially you would be shorting the cap with the coil , the only thing that would hold back the inrush of current would be the inductance of the coil..
it was $31.00 btw , not cheap.. but very fun to work/play with..
 
A super cap would take a fairly long time to discharge into a coil.
Your projectile would be accellerated as it is pulled toward the coil, then as it goes past it would be pulled back. The timing for the cutoff time is critical.
Also, the current builds up in an inductor slowly. The projectile might be gone before the current is max.
 
thats the best part .. a coil gun runs on current not voltage..
one , or two ( in parallel )would do it..
How is that? 70V across a 2.5V cap would fry it right?

I've been thinking about coil guns. One way that you could get the timing right would be to get a camera set on it's highest shutter speed. Then have an LED turn on whenever the coil is on. That way you could actually "see" the coil turning on in relation to the projectile.

This would help even more in a multi-stage coil gun. I wonder just how fast the camera would need to work.
 
What i meant was a coil's magnetic strength is proportional to the current through it..
ie more current more magnetic strength.
in the circuit below there is no initial current , but the voltage on the cap is initially 2.5v.
as you can see the current instantaniously jumps up to around 6.23 A
In this circuit the resistance of the coil has a lot more of an effect than the inductance , on the current .. the coils resistance is .4 ohms..
after it fires you could allways just shot it off .
 

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Put some reasonable resistance and inductance into your coil then stretch the timebase of the 'scope (milli-seconds) to show the slow rise of current in an inductor.

The projectile might be gone long before the coil's current reaches max.
 
I think that 10mH is a reasonable value for a coil that is 0.4 ohms.
Then it will reach half current in 17.5ms, and max current in 125ms.
It will cause the projectile to move very slowly.

Why doesn't your sim show an exponential discharge current of the cap?
 
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