What is Digg?41 Comments
- inactive, on 10/12/2007, -0/+13Is it just me or can I not find the link to the the info on how to actually make this? This does however look very awesome and it's the first hack i've seen which I will actually make :) Wow.
- rageguy, on 10/12/2007, -2/+12A quick Google for "9v supercap filetype:pdf" revealed this pdf.
http://fussychild.net/2005/precollege_saturday/Spring06/10-2003%2520SuperCap%2520Battery.pdf
Seems to be the 9v SuperCap battery specs refered to in the article. - Roger, on 10/12/2007, -0/+9Depends on what you call a "light" load.
Can anyone else not locate the pdf link? - special4k4, on 10/12/2007, -0/+7Actually, it will not last quite as long as he claims.
See afroman's comment (http://handhelds.hackaday.com/2005/12/06/supercap-9v-battery/1#c385056):
"He says it will run a light load for 3 hours without a recharge... but that's a pretty big exaggeration. He states the quiescent draw of the converter is 2ma at 2.3V, meaning a 4.6mW draw with no load, or 0.0046 joules per second...After about 1.6 hours of this circuit powering absolutely NOTHING, the cap will have fully discharged." - Roger, on 10/12/2007, -1/+8Here we go (from google):
http://fussychild.net/2005/precollege_saturday/Spring06/10-2003%2520SuperCap%2520Battery.pdf - Blah_Blah_Blah, on 10/12/2007, -3/+10Lasts 3 hours actually. Awesome "hack".
- HappyScrappy, on 10/12/2007, -0/+6Yeah, and if you hook to a common LED (25mA), it will last under a minute (if you hook it to the 9V outputs, you'd be smarter to put it directly to the 2.3V cap).
This thing has 6.4mAh of capacity at 2.3V, after the switcher it's more like 1.5mAh. A NiMH 9V battery has 230mAh of capacity, about 200x as much. - teckjunkie, on 10/12/2007, -0/+6They didnt forget it, the link was there when they first posted the story dec. 6 2005. However link probably went down since then.
- Roger, on 10/12/2007, -0/+5Connect the terminals to a DC/AC source between 4 and 12V
- Roger, on 10/12/2007, -0/+5"Do capacitors lose their ability to hold a charge"
No. And if they did, it wouldn't be on the same order as ordinary batteries.
"Is their any possible way to replace AA batteries with capacitors, and still keep the form factor?"
You could modify this circuit for 1.5V output, but it'd probably be too big. Capacitors don't give constant voltage outputs, so you can escape the additional circuitry (i.e. the switching regulator). Maybe if you used SMD components it might work, but I dont think I'd be worth the effort. - socket, on 10/12/2007, -1/+6Cost is the problem. You'll end up paying about $75-$100 for a 10F ultra cap. Sorry but I don't care how fast it charges I'm not paying that much of a DIY battery I wouldn't trust for *****. Also depending on application I have a feeling discharge times will very greatly.
- socket, on 10/12/2007, -0/+5Actually, you can get a 10F Maxwell boostcap for about $10, but generally most places want you to order like $75 or more.
- cjsedwards, on 10/12/2007, -0/+5"You'd use your engine for five minutes near the end of the charge of the capacitors, then be charged up and just running on electricity - how cool would that be? That would be an insane amount of gasoline saved."
Unfortunately you're not limited by the rate at which the capacitor can be charged, your limited by the current output of your alternator.
The rate at which the capacitor charges is proportional to the current going into it and your engine can only burn gas at a certain rate. Plus, the energy lost in converting the gas to electricity makes it more efficient to just use to gas to propel your vehicle. It is the same confusion people have thinking hydrogen is clean. You still need the energy to extract the hydrogen. - NicP, on 10/12/2007, -0/+4http://en.wikipedia.org/wiki/Image:Supercapacitors_chart.svg
Thats a diagram of the energy density of batteries and caps. So caps can charge and discharge quickly but store less energy, where batteries store more energy but need to be discharged and charged more slowly. They are suited for different uses, as mentioned above a cap will lose its voltage as it is discharged, whereas batteries tend to maintain close to their nominal voltage for most of their discharge cycle. - NicP, on 10/12/2007, -0/+4The energy density of a capacitor is much less than that of a battery
- inactive, on 10/12/2007, -0/+3Do capacitors lose their ability to hold a charge after multiple uses/recharges, like that of a NiMH or Li-Ion battery? Is their any possible way to replace AA batteries with capacitors, and still keep the form factor?
- NSMike, on 10/12/2007, -5/+7Capacitors will one day replace batteries, if nanotechnology gets off the ground.
Capacitors hold charge differently than chemical batteries. Instead of relying on reaction, a capacitor stores the electricity, essentially. The problem with capacitors is that they're dependent on surface area for the amount of charge.
Nanotechnology could potentially change that by providing tremendous amounts of surface area in very small spaces, therefore increasing the capacity of a capacitor, with equally fast charge times. You could, potentially, see laptop "batteries" that last for 6 hours and charge in five minutes. The same could occur for hybrid cars. Imagine that! You'd use your engine for five minutes near the end of the charge of the capacitors, then be charged up and just running on electricity - how cool would that be? That would be an insane amount of gasoline saved.
If you can't tell, I'm excited about the prospects of carbon nanofiber and capacitors. - inactive, on 10/12/2007, -0/+3There is also a higher chance of explosions.
- localzuk, on 10/12/2007, -2/+5You're not gonna get much of an explosion from a capacitor the size of your thumb. Maybe a small 'pop' but not a fullblown explosion.
- drwtsn32, on 10/12/2007, -1/+4repeat after me
It's not the fire, it's the heat.
It's not the fire, it's the heat. - rocketryguy, on 10/12/2007, -0/+3A Battery is electro-chemical, where a capacitor is essentially a static charge device, solid-state in the sense that it doesn't change chemically regardless of what charge it's carrying.
But as commented above, they currently don't have nearly the same energy density.
However, research into super-capacitors has yielded some progress. One potential application is in electric hybrid cars, where you can work with the size/weight, since it does mean that you don't have to replace them at 50K Miles or so.
With an intelligent controller one could also use them to take temporary acceleration loads and minimize battery charging cycles, sort of a eletric-cache buffer. But that's probably not worth it. Eventually replacement of the batteries entirely with caps would probably make more sense as the technology progresses.
Batacitors, combining the two types of storage seem to occasionally rear their heads, then disappear, anybody know what's up with them lately? - PointAndClick, on 10/12/2007, -0/+3No, it's not just you. I never seem to see the links on hackaday.
Neat DIY project, but I think i'll just go dig through "the drawer" in hopes of finding one more good battery. - inactive, on 10/12/2007, -0/+2smart invention, maybe the reason was that supercap which kept this back and it's more environmentally sound, but I still don't feel any regret when I drop the storage batteries to the trash :>>
- zupzupper, on 10/12/2007, -0/+2@rockefeller
Glad someone else was thinking this. I wouldn't trust most people to mess about with the little 400uF caps from camera flashes, you touch a 10F cap the wrong way it's going to knock you into the middle of next week. - thunderer, on 10/12/2007, -2/+4The problem is, I only use 9 volt batteries with $500 wireless microphones, and there's no way I'm trusting this with them.
- waz67, on 10/12/2007, -1/+3I once connected a 50v power supply to an experimenters breadboard without noticing the electrolytic capacitor still on the board (a small one, only about half an inch tall). The rather large BANG (not a pop) made me just about jump through the ceiling, and left a cloud of smoke above the desk and tiny bits of paper scattered throughout the room.
- HappyScrappy, on 10/12/2007, -0/+2A resistor would work too.
But what's the point? The reason is discharges so quickly is because it contains so little energy to start with. Adding an inductor isn't going to fix this. - aurifex, on 10/12/2007, -0/+2Won't last as long as he stated, realistically, but a cool hack nonetheless.
- keba, on 10/12/2007, -1/+2@ zupzupper
The 400uF camera caps (flash caps) charge close to 300V ;so touching it gets pretty nasty,but these supercaps charge to around 3 V ,so touching it would not be dangerous ,
Also dischrging it with a screwdriver would produce some nice welding flares.....and an explosion maybe...
(sticking your tongue into it,is a completely diff thing) - thunderer, on 10/12/2007, -1/+2First, it's microphones.
And I just pay for the batteries; when you go through 5-10 a week at a buck or two each, the cost adds up. - special4k4, on 10/12/2007, -0/+1Not at 9 volts... At most you'll get a tingle if you lick the terminals. The skin's resistance is high enough that minimal current will flow for such a low voltage (on the order of microamperes for dry & dirty skin and milliamps for wet skin). Think Ohm's Law. The effective serial resistance of supercapacitors (ESR) is also quite a bit higher than the ESR of electrolytic and other capacitors, further limiting the current.
- AngryPenguin47, on 10/12/2007, -0/+1couldn't you throw in a larger inductor in series to slow the discharge rate of the capacitor?
- raptordrew, on 10/12/2007, -2/+2How would you charge this "battery"?
- khyberkitsune, on 10/12/2007, -4/+4repeat after me
It's not the voltage, it's the amperage.
It's not the voltage, it's the amperage. - inactive, on 10/12/2007, -1/+1Looks like they forgot to include it in the post :(
- Roger, on 10/12/2007, -7/+4What do capacitors have to do with Ghostbusters?
- wurzelgummage, on 10/12/2007, -6/+3Completely useless.
- rockefeller, on 10/12/2007, -10/+610F cap.....
"Whatever you do, don't cross the streams!!!!" - Roger, on 10/12/2007, -7/+2You spent $500 on earphones but won't buy 9v batteries?
- freonchill, on 10/12/2007, -6/+1nevermind
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