Make supercapacitors from graphite in a DVD burner

The outline is that you can deposit graphite oxide (a cheap bulk material) onto a film of PET (the plastic used in Coke bottles), hit it with a commodity infra-red laser (such as the one in a $30 LightScribe DVD burner) and end up with a form of activated carbon material that can be used as the electrode in an electrolytic capacitor.  Add some aluminium foil, separator membrane and electrolyte and you've got cheap, robust energy storage.  The headline numbers are a few hundred milliFarads per cubic centimetre at a few volts, which works out to 1.36kWh per cubic metre of stacked capacitors.  It's still about 50 times less energy per volume than lead acid batteries, but you could store as much energy as your house will need overnight in the size of a garden shed or a set of bunk beds.  They charge/discharge in seconds and retain >95% capacity at 10,000 cycles so seem suitable for storage to even out intermittent energy generation from, for example, solar or wind power. I'm really thinking about cost here- unless I'm missing something fundamental it doesn't seem like producing these on a high volume roll-to-roll process would be excessively difficult, and the cycle life means the replacement time would be many years even in heavy usage.  Could you get sufficient kWh per dollar to make these a viable storage mechanism for home-scale renewables? There's a more informative article here.

Posted by PKM 6 years ago


where to find/recycle supercapacitors?

Been wondering just in what and where do they use super caps? i recycle any an all where i can and thought sum ofs ya could give me a clue as to where would a good source?i have coffee cans full of reg caps taken outta pcs an such but as far as i can tell i've never happened upon any super caps in anything yet.any info would help! thank you.

Posted by ripit 6 years ago


Charging BoostCaps

I recently got a few of the 3000 farad 2.7 boost caps from electronic goldmine.  I have a quick question about charging them.  Applying a higher than rated voltage before the capacitor is charged all the way would be fine, right?  The voltage drop should cause the source voltage to approach 0, thusly below the 2.7 volt rating.  As an extreme example, lets say you simply hooked up a 9 volt battery to it.  Since the battery can only supply like 200mA, the voltage drops to nearly 0 as the capacitor appears to be a dead short.  The dielectric (or ion exchange or napheon membrane or whatever it is in a ultracap, lol) should be fine, correct? My main goal is to later hook up one or two of these for a regenerative brake system of something like a small gokart or bike or something.  Stopping at 30mph is like (assuming 200kg total mass) 20k joules, and each one can hold about 10k joules, and assuming a max efficiency of like 30 or 40% (I think itd be much lower, though), these capacitors could brake a gokart going fairly several times without having to be discharged inbetween cycled (but of course they would be).  For braking, could these essentially be hooked up directly (of course with pwm, and other things, but in essence:) to the motor with a little protection circuitry to prevent overcharging the capacitors?  Or would the higher voltage instantly puncture and destroy the boostcap?

Posted by guyfrom7up 7 years ago


Supercapacitor Voltage Draw

If I am charging a super capacitor with buck converter, that is a 1 amp, 1-18 volt output, and the capacitor is rated for 2.5 volts, how do I stop the buck converter from feeding it more than 2.5 volts? When I attach the capacitor to my digital power supply, it starts charging, and the voltage slowly increase to be more than 2.5 volts, at which point I turn it off. I was wondering will it draw more than 2.5 volts from my buck converter? If so how do I stop it?

Posted by merlinj 2 years ago


Printing Graphene?

Has anyone tried this? I have a lightscribe. Looking at the video it seems that all I need is some graphite oxide. I tried embeding the video but I don't think it is going to work. Here is a link to the video. The Super Supercapacitor | Brian Golden Davis from Focus Forward Films on Vimeo.

Posted by ehudwill 5 years ago


Mysterious translated version of an Instructable published

I'm not sure what's going on, but... I submitted an Instructable on 30 June. It was subsequently featured in the technology section. A few hours ago, I noticed a new draft of that Instructable, all in Spanish. The Spanish version of the Instructable was just published a few minutes ago. I neither created the draft nor published the Spanish Instructable. Was the original Instructable translated by an administrator? Is this normal? 

Posted by supercapacitor 4 years ago


Tree Speakers, Melon Brain, Pumpkin Silly String Shooter

Tree Speakers Melon Brain Pumpkin Silly String Shooter NES DVD Player Lady Gaga Caution Tape Costume Restoring Old Sneakers Cardboard Costume Helmet Supercapacitor USB Light Lady Gaga Bubble Costume Lady Gaga Baby Suits DIY Christian Louboutin Petal Sandals Sugru Mouse Grip Homemade Wakeboard Winch Gruesome Zombie Makeup Build a Full Tang Knife

Posted by randofo 7 years ago


BOUNCE: original game (download here)

BOUNCEBOUNCEBOUNCE [download] BOUNCE is an original 2D platform style game built in Java. The game incorporates game elements like destructible terrain, 3rd person shooting, and puzzles, to provide an experience similar to such games as Mario and Minecraft. You, a lone circle in a world of squares, must make your way through 50 levels to save the galaxy from destruction. Along the way, you'll face laser shooting robots, parkour puzzles, and fire-breathing dragons. More information available at http://www.java-gaming.org/topics/iconified/27023/view.html.

Posted by supercapacitor 4 years ago


Paper Batteries

Has anyone read anything about the up and coming Paper (thin) batteries ? Paper Batteries: A paper battery is a flexible, ultra-thin energy storage and production device formed by combining carbon nanotubes with a conventional sheet of cellulose-based paper.A paper battery acts as both a high-energy battery and supercapacitor, combining two components that are separate in traditional electronics. This combination allows the battery to provide both long-term, steady power production and bursts of energy. Non-toxic, flexible paper batteries have the potential to power the next generation of electronics, medical devices and hybrid vehicles, allowing for radical new designs and medical technologies.What do you think? Will it replace these monsters one day?

Posted by Goodhart 10 years ago


newly created Instructable not showing up in Recent section or search results

I recently posted this Instructable (https://www.instructables.com/id/12V-180kV-A-Battery-Powered-Marx-Generator-and-int/). However, it seems to have been caught in the filters like many others before it (I'm thinking the word "Communism" set off the alarms). I have looked over several other threads concerning this issue and all seem to have been handled. I figured I'd ask anyway because I have a few questions: How long does it typically take for a filtered Instructable to be manually approved? Will this affect the Instructable's approval for a contest that closes today? Will the Instructable appear at the top of the Recent section when it is approved or will it be offset? Thanks!

Posted by supercapacitor 4 years ago


Electrolytic vs supercap for CD spotwelder?

I need to make a cheap spotwelder to rebuild some battery packs(e.g,. welding thin nickel strips).My options are:(a) Try to find most of a farad at up to 25V or so on eBay. This could take a while. (Buying new electrolytics in the 0.1F range and above at these voltages is pretty expensive.)(b) Go for supercaps from Digikey (e.g). They've got some 5V 1F models for only a few bucks, and some "fast-discharge" ones for 10x more. Of course, if I go for more than 10V or so, I'll have to build some sort of charge-balancing circuit around the series caps, and I'd rather not unless it's really the best way to go--- though it might be as simple as a resistor in parallel to each cap.(c) Try one of these weirdo "digital supercapacitors" that are all over eBay for the crowd who fill their entire trunk with stereo amps. These look like they're rated at 1-5F at 13.8V and (I would hope) include some sort of charge balancer. Dunno if they're suitable for the sort of instant-discharge I want for a welder, though.I'm having difficulty figuring out:(a) How fast a discharge I need for a spotwelder anyway; I'm going to be using an SCR to trigger it and presumably want the lowest-inductance arrangement I can get, but are we talking milliseconds or microseconds?(b) What can I get out of a supercap? Milliseconds or microseconds? I haven't worked with supercaps before, and most people who seem to be designing circuits with them are using them as batteries.Other random questions:My reference design had 0.5 to 1F at 0-25V through a 600V 50A TO-65 SCR; whatworries me are things like http://www.avxcorp.com/docs/Catalogs/bestcap.pdf,whose page 3 shows that non-ultra-low-ESR supercaps (e.g., theaffordable ones) seem to have virtually no capacitance for pulsewidths of 10ms or less. (The BestCaps in that datasheet claimsomething like 60% of nominal instead, which is pretty good!)I dunno how narrow the pulse width needs to be to get good welds,but I'm guessing pretty narrow---for example, one guy claimed inhttp://www.philpem.me.uk/elec/welder/ that just the difference inputting the SCR on the low side and not the high side (so the triggerfor it didn't have to go through the wires, electrodes, and workpiece)worked a whole lot better, which implies to me that he might betalking microseconds. But I just don't know.]Of course, I also don't know whether I need 0.5 F at 10V or 1F at25V for the things I'm considering.Not to mention---the 50F caps at http://dkc3.digikey.com/PDF/T072/P1354.pdf(some of which claim ESR's of 0.025 ohm at 1kHz) have these skinny little0.5mm leads on them. How in hell would these leads not be vaporized if Icharged up the cap and then shorted it, as a spot-welder would be doing?(And sure, I could try to attach #4 copper wire to them---somehow---andsend that to the sharpened tips on my welding electrodes, but boy I feelsilly doing that---seems like whatever part of the cap's leads aren'tattached to the heavy wire will just evaporate when shorted, if they canreally dump that kind of current, even if it -is- just for milli-to-microseconds.)The Instructables site has some rambling about using supercaps for CDspotwelders, but it's just rambling---nobody who's actually built oneusing them, for example, or who seems to talk about discharge rates,etc.

Posted by HilaryGage 11 years ago