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Registered Member #99
Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637
... wrote ...
Seems like for making the H2/O2 you would be best off using a little bit of metal dipped in a pool of water, with a little bit of salt in there to get the current flowing... As long as you only use a little voltage (3v) you should get mostly O2 and H2 out. Then let the bubbles rise up onto the electrodes and life would be good
As to their prices, I didn't see a $22 piece of pure carbon, but some pieces of carbon that had been machined with small channels in them ($$$) or pieces that had been doped with platinum ($$$$)... Their prices for the pem membrane seems decent for the quantities they are selling...
As to the % methanol; I would assume you would just mix a little pure methanol into the KOH solution. You could use something weaker, but add more of it to compensate. A page linked by yours states that 1-4M KOH should be used, so it is mostly water anyway.
Also, about the platinum... I think that instead of using wire you would get much more bag for the buck with Pt plated wire or foil. Seems like a 300u layer is pretty cheap... I calculate 15mg/in^2 (double for double sided) so at $38/g that is only $1/in^2 of platinum But since we can't get foil with a 300u Pt plating for anywhere near what it costs in the platinum I think we should stick with a 2mg/in^2 Pt doped carbon for $20/in^2 as sold by the fuelcellstore
Yea, all very costly. As to the relatively low price and decent output of the mini fuel cell using methanol, i beleive that it is actually much cheaper than they are selling for. The smart thing they do is NOT mention what the electrodes are made of. From the picture, they look like glass/plastic beaker and some red tube made of plastic. Im betting a small piece of carbon sheet lays at the bottom of the "beaker/electrode" and the other electrodes lays in the red thing. They are kept almost touching and both emersed in the KOH electrolyte/methanol mixture and viola! So, since I already have bought the 3 feet of hair thin 92%Platinum, 8%tungsten wire, perhpas I will get myself some cheap carbon(deffinataley not from them) and recreate that arrangemet...How about this->
Electrodes->Two round carbon rods like those found in old batteries. Both will have the platinum allow wire coiled around them. They will be emeresed into the KOH (NaOH instead?) eletrolyte. Then when i want the magic to happen, in goes the methanol.
If this all sounds good, I will order some methanol, ( i saw 500mL of anahydrous methanol online for like 5$) plus some KOH. If I cannot find some old batteries, anyone know where I can find some carbon electrodes?
Registered Member #191
Joined: Fri Feb 17 2006, 02:01AM
Location: Esbjerg Denmark
Posts: 720
i think i saw a demo somewhere on the, where they first connect the cell setup to a powersource, let it run as electrolysis of water, let teh H2 and O2 forms on the Pt wires. then if you take away hte power source, the H2 and O2 will recombine, and give out power. not sure about efficiency tho.
as for carbon rods, if you can find old batteries, get new ones? dollar store batteries? as lond as they are Zinc Carbon type, they will have the carbon rods.
Registered Member #99
Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637
Electroholic wrote ...
i think i saw a demo somewhere on the, where they first connect the cell setup to a powersource, let it run as electrolysis of water, let teh H2 and O2 forms on the Pt wires. then if you take away hte power source, the H2 and O2 will recombine, and give out power. not sure about efficiency tho.
as for carbon rods, if you can find old batteries, get new ones? dollar store batteries? as lond as they are Zinc Carbon type, they will have the carbon rods.
I did this last night with some drain cleaner and pencil lead. It worked...But such a mess it makes!I cant find pure sodium hydroxide in town anymore(and my stupid little brother used it up when i showed him what it does to aluminum foil). I got something else with lotsa other crap in it.
I will go to the dollar store today, get some cheapo batteries and "rape" them for the carbon rods. Then, I will look for sodium hydroxide there(pure), else i will order some KOH online. Whats the difference between the two? As far as fuel cell goes? After that, i just will wait for my Pt. wire and some methanol, and see if it is sufficient enough. If not, im just going to buy their 50$ fuel cell capable of some 350mA at im guessing .5 volts. Open source is .9volts, so i plan to build a joule thief style converter to boost that tiny voltage up enough for an LED. Seeing as I only need some 10mA or so at a few volts, this fuel cell should be more than enough. Can a PEM cell designed for hydrogen gas work with methanol?Doesnt methanol release hydrogen gas anyways?Perhaps the mthanol will damage the PEM...Id ask fuel cell store, but i doubt they would reveal those secrets Matt
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Methanol would poison the PEM with CO and it will die very quickly. (read wiki)
PEMFC is probably only 'usable' type of cell when many of them are stacked, those small methanol-dipping cells probably won't go much further than lighting a LED. Maybe if you find a way to greatly reduce their size and stack a lot of them together.
SInce you only need it for demonstrative purposes then I think you are on a right way...
Registered Member #99
Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637
Firkragg wrote ...
Methanol would poison the PEM with CO and it will die very quickly. (read wiki)
PEMFC is probably only 'usable' type of cell when many of them are stacked, those small methanol-dipping cells probably won't go much further than lighting a LED. Maybe if you find a way to greatly reduce their size and stack a lot of them together.
SInce you only need it for demonstrative purposes then I think you are on a right way...
I spoke with the guy from fuelcellstore about it. He said it may work, just wont be as efficient. Since it went on sale today down to 39$, i decided to give in and get it. It will output.6-.9 volts at 350mA. I dont need more than 10mA for a superbright LED, so along with a "joule thief" this out to do it for now. I just need a clean way to produce and reliably store hydrogen gas. Ideas?
I did get some carbon rods from a dollar store 6volt battery. What a messy job, and they have TAR in them, goddarn!They are soaking in water to get clean. I will still do the methanol cell experiement. I plan to use two of these large carbon rods. Wrap the Pt. wire around each, and dunk them in a KOH + Methanol solution. See what happens! Any ideas? Any predictions? 3 feet of 43awg 92%platinum wire/8%tungsten...
Registered Member #19
Joined: Thu Feb 02 2006, 03:19PM
Location: Jacksonville, FL
Posts: 168
I built a small fuel cell with NaOH, some of that hair thin platinum wire for the electrodes, and bubbling h2 and o2 over them. It produced about 150ma average and probably only several ma. I tried using platinum wrapped around carbon but I ended up making a battery. That seemed to happen every time I put two different conductors in the solution. I think the fuel cell page posted by carbon rod is the best guide I have seen but it will cost a bit of $$.
Registered Member #99
Joined: Thu Feb 09 2006, 06:10PM
Location: florida, usa
Posts: 637
Nick wrote ...
I built a small fuel cell with NaOH, some of that hair thin platinum wire for the electrodes, and bubbling h2 and o2 over them. It produced about 150ma average and probably only several ma. I tried using platinum wrapped around carbon but I ended up making a battery. That seemed to happen every time I put two different conductors in the solution. I think the fuel cell page posted by carbon rod is the best guide I have seen but it will cost a bit of $$.
That fuel cell construction seemed poorly planned out considering the cost of the stuff used. If i had spent the money to get that stuff, id opt for a bit better than plastic syringe tubes and such
Anyways, I ordered a reversible PEM cell from the place for 40$ (was on sale). It will output .6 to .95 volts and 350mA. With a joule thief, I should have no trouble lighting a superbright LED. The cell is reverisble too, so I can use it to produce hydrogen gas via a solar cell and some water.
Seeing as I already bought the stuff to make a methanol fuel cell, I will give it a go. Its GOT to work, as fuelcell store has a super simple one, looks like maybe just carbon electrodes with platinum on them emeresed in a KOH + methanol solution. Its GOT to work...
EDIT: I think i may have just created a fuel cell! NaOH electrolyte, and two carbon electrodes emersed in the solution. I applied 9 volts to create H2 bubbles, then connected the joule thief to the output. Very brightly lit LED! The LED stayed lit for maybe a minute, then turned off. After turning off, there was about 0.5 volts stil showing up on the DMM. When the electrodes were pulled out (removing the bubbles attached to both electrodes, and put back in, no output at all present. This appears to be fuel cell, no? I dont understand why this is working without a platinum catalyst? Next step is to add the platinum wire to the electrodes and see if that improves the operation any... Hurray joule thief! So lets hope a methanol cell will work like this as well. That will consist of a KOH solution with the same electrodes, except covered in Pt. wire and of course methanol added.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
I just tried the peltier experiment, common refrigerator peltiers work pretty well
By just heating one side with hand I get few hundreds of milivolts.
After heating one side quickly with cigarette lighter I can get up to 1,3 volts at almost an amp. I also get pretty good results if I throw and ice cube on one side. No liquid nitrogen needed
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Fuel Cells
But since we can't get foil with a 300u Pt plating for anywhere near what it costs in the platinum I think we should stick with a 2mg/in^2 Pt doped carbon for $20/in^2 as sold by the fuelcellstore 
