making potassium (per) chlorate

[WSM]

Drill out the copper for approx. half an inch leaveing the Pt coated Nb 'tube' behind.

You can then fill in this 'tube' with epoxy etc. You can leave the very end of the 'tube' unfilled with epoxy

and when the epoxy has set you can pinch the tube shut to hold in the epoxy and further seal the end.

An alternative is to use this anode material as a U shaped anode. ie both exposed copper ends outside

the cell.

 

Oh, I forgot to mention, I gave up on using epoxy in the cell liquids at all. It tends to erode and not hold up. PVC and Teflon seem to be the best with some others running a close second. As frank suggests, keeping the copper end of things out of the solution is a better, simpler solution to the problem...

 

WSM

[pyrojig]

Hi frank,

 

I thought of using the U shape, too. I even considered a (or several) long, very skinny U shapes spot-welded to a titanium lead for an anode. It's funny how so many different experimenters come up with similar solutions. This is great. Thanks for jogging my memory .

 

WSM

 

WOW, that is a trip!!! I thought the same thing when I first read your post WSM...

The U shape would solve the contamination issue. I second the statement on epoxy, it is only a temporary fix, nothing more.

[WSM]

WOW, that is a trip!!! I thought the same thing when I first read your post WSM...

The U shape would solve the contamination issue. I second the statement on epoxy, it is only a temporary fix, nothing more.

 

One sealant that looks like it might work well in a chlorate cell (and one I'd like to experiment with) is Viton rubber. There are several formulations for the fluoroelastomer known as "Viton", some more effective against hypochlorite than others, and I've collected a couple. One positive aspect of Viton is that it's soluble in acetone and a few other keytones.

 

If I can make a syrupy or pasty solution of Viton, I can use it to coat metal components to test in an active cell, to determine Viton's ability to protect otherwise affected materials. Imagine the possibilities; dipping metalic thermal sensors to protect them and have an effective way to monitor temperature in your cell or covering electrical connections to protect them from salt creep or chlorine attacks. It might simplify sealing a cell with an uneven surface by filling the gaps (sort of like automotive silicone "Form-A-Gasket" material). The list goes on...

 

There are several ways to solve the myriad problems encountered in our electrochemical experiments. Thank you for suggesting alternatives, some or all of which may well open the door of success for one of our readers. Keep 'em coming...

 

WSM

[pyrojig]

I like the Viton idea. One Q. is will it stand up to temperatures w/o warping or degrading ? That is the true acid test. We know that Viton is very resistant to most all chems, but heat is a factor that seems to kill . This may be more-so true if the viton is on the electrode to cover cracks or unfinished ends/ electrode post, ect . Pretty much anything that gets extremely hot.

[WSM]

I like the Viton idea. One Q. is will it stand up to temperatures w/o warping or degrading ? That is the true acid test. We know that Viton is very resistant to most all chems, but heat is a factor that seems to kill . This may be more-so true if the viton is on the electrode to cover cracks or unfinished ends/ electrode post, ect . Pretty much anything that gets extremely hot.

 

I believe it can handle up to 400^oF (204.4^oC); certainly more than twice what we expect in a perchlorate cell. There are several solvents that Viton can't take, but ozone, sunlight, heat, oils, chlorine, oxidizers, etc., it can!

 

As a fluoroelastomer, Viton is like the "Teflon" of rubber materials. Again, there are several formulations of "Viton" and I have great hopes for the Viton B formulation in our cells.

 

WSM

Edited September 1, 2012 by WSM

[Swede]

Viton has been outstanding for me. The thought of a liquid viton that can be coated on or otherwise molded is a great idea, and worthy of experimentation.

 

Barring that, it is good stuff to have on hand as both sheet and cord stock. For cord, I'd stock 3/16" or 1/4", heavier stuff that seals better, and some sheet from 1/32" thick on up. I've used it as gaskets with great success. It's pretty much immune to the chlorate process.

 

Here is a piece of viton acting as a gasket on a bucket cell adapter rig:

 

http://www.5bears.com/s2f/s2f013.jpg

 

I'm working on what I hope will be a valuable addition to the body of knowledge. I'm taking all of the numbers and data that we have painstakingly gathered over the years, and verifying that they do in fact work for a low-tech setup that uses no electricity beyond the electrodes, and no moving parts. Starting chloride levels without actually measuring the chloride, terminating chloride levels derived from efficiency and ampere-hours, all using an HDPE bucket as a disposable container.

 

5 gallon buckets plus a lid cost about $5 in the big-box hardware stores. I'm going to execute the low-tech run using drip HCl but simultaneously verify that it works properly by checking chloride and pH with Hach Cl- strips and a pH meter. If all goes as planned, I'm hoping efficiency will be near 90%, but with an investment of only an HDPE bucket, some KCl, a $3 IV drip using HCl, and of course a power supply and MMO electrodes.

 

Some pics - remember that this bucket cell adapter is high-tech, but a simpler one would do just as well if it can be made to seal correctly.

 

http://www.5bears.com/s2f/s2f002.jpg

 

http://www.5bears.com/s2f/s2f008.jpg

 

http://www.5bears.com/s2f/s2f012.jpg

Note the bleaching on the grey PVC sheet in the above pic where it was subject to chlorine on previous runs. Beyond the decoloration, the plastic is 100% sound.

 

http://www.5bears.com/s2f/s2f027.jpg

 

On eBay, I picked up 50 feet total of some 4 gauge welding cable. 4 gauge is a good size, capable of 120+ amps, and more than adequate for 98% of anything we'd do. And much cheaper than the heavier stuff.

 

http://www.5bears.com/s2f/s2f032.jpg

 

http://www.5bears.com/s2f/s2f033.jpg

 

I'm going to resurrect my old blog and provide a lot of detail. Again, the goal is low-tech but high efficiency. The 5 gallon bucket cell should deliver ~ 220 grams per liter of KClO3 taking a 15% Cl- stock down to 8% Cl- using the "IRS" worksheet I posted earlier. That means the yield should be close to 4 kilos in a single run, including dry and wet (dissolved) chlorate.

 

I've also picked up 4 ea. 5 gallon HDPE carboys to stock used electrolyte and raw KCl solution. These things are expensive, even used. The minimum price seems to be about $15 each, but there is no alternative... the stuff has to be stored somewhere, and whatever you use needs to be fairly stout.

 

After this, I'm going to put chlorate aside and focus on perchlorate. We've pretty much got the chlorate process nailed, and there's not much left to investigate. WSM, thought you'd like the looks of this 2-element Ti cathode spot welded from sheet. It surrounds a single anode on both sides, but uses a single strap for connection to the power supply. Note all the white smut that seems inevitable on a Ti cathode. it doesn't hurt a thing, and can be cleaned off with some steel wool.

 

http://www.5bears.com/s2f/s2f014.jpg

[Swede]

I forgot to mention - some guys have sealed exposed reactive metals like Cu by encasing them in glass. Generate a blob of molten glass using a torch, poke the Cu (be sure it is bone dry and pre-heated) into the blob, and manipulate so as to leave the blob attached to the Cu.

 

I have little experience with glass work like this, but I've seen some pictures on the net that show this, so it may work OK.

 

On perchlorate, I hate to say this, but my gut feel is that when the smoke clears, it's going to be hard to beat Pt despite the cost. Perhaps the thrust of experimentation should be additives or processes that minimize Pt erosion, and one step in that direction is chlorate stock that has as little Cl- in it as possible, which is where potassium salts shine - we can separate pure K crystals from the surrounding chloride liquor with relative ease. Not so easy with sodium.

[WSM]

Viton has been outstanding for me. The thought of a liquid viton that can be coated on or otherwise molded is a great idea, and worthy of experimentation.

Barring that, it is good stuff to have on hand as both sheet and cord stock. For cord, I'd stock 3/16" or 1/4", heavier stuff that seals better, and some sheet from 1/32" thick on up. I've used it as gaskets with great success. It's pretty much immune to the chlorate process.

Here is a piece of viton acting as a gasket on a bucket cell adapter rig:

 

http://www.5bears.com/s2f/s2f013.jpg

 

I'm working on what I hope will be a valuable addition to the body of knowledge. I'm taking all of the numbers and data that we have painstakingly gathered over the years, and verifying that they do in fact work for a low-tech setup that uses no electricity beyond the electrodes, and no moving parts. Starting chloride levels without actually measuring the chloride, terminating chloride levels derived from efficiency and ampere-hours, all using an HDPE bucket as a disposable container.

5 gallon buckets plus a lid cost about $5 in the big-box hardware stores. I'm going to execute the low-tech run using drip HCl but simultaneously verify that it works properly by checking chloride and pH with Hach Cl- strips and a pH meter. If all goes as planned, I'm hoping efficiency will be near 90%, but with an investment of only an HDPE bucket, some KCl, a $3 IV drip using HCl, and of course a power supply and MMO electrodes.

Some pics - remember that this bucket cell adapter is high-tech, but a simpler one would do just as well if it can be made to seal correctly.

 

http://www.5bears.com/s2f/s2f002.jpg

 

http://www.5bears.com/s2f/s2f008.jpg

 

http://www.5bears.com/s2f/s2f012.jpg

Note the bleaching on the grey PVC sheet in the above pic where it was subject to chlorine on previous runs. Beyond the decoloration, the plastic is 100% sound.

 

http://www.5bears.com/s2f/s2f027.jpg

 

On eBay, I picked up 50 feet total of some 4 gauge welding cable. 4 gauge is a good size, capable of 120+ amps, and more than adequate for 98% of anything we'd do. And much cheaper than the heavier stuff.

 

http://www.5bears.com/s2f/s2f032.jpg

 

http://www.5bears.com/s2f/s2f033.jpg

 

I'm going to resurrect my old blog and provide a lot of detail. Again, the goal is low-tech but high efficiency. The 5 gallon bucket cell should deliver ~ 220 grams per liter of KClO3 taking a 15% Cl- stock down to 8% Cl- using the "IRS" worksheet I posted earlier. That means the yield should be close to 4 kilos in a single run, including dry and wet (dissolved) chlorate.

I've also picked up 4 ea. 5 gallon HDPE carboys to stock used electrolyte and raw KCl solution. These things are expensive, even used. The minimum price seems to be about $15 each, but there is no alternative... the stuff has to be stored somewhere, and whatever you use needs to be fairly stout.

After this, I'm going to put chlorate aside and focus on perchlorate. We've pretty much got the chlorate process nailed, and there's not much left to investigate. WSM, thought you'd like the looks of this 2-element Ti cathode spot welded from sheet. It surrounds a single anode on both sides, but uses a single strap for connection to the power supply. Note all the white smut that seems inevitable on a Ti cathode. it doesn't hurt a thing, and can be cleaned off with some steel wool.

 

http://www.5bears.com/s2f/s2f014.jpg

 

Hi Swede,

 

Thanks for the excellent photos and update. I'd like to share a similar project I've started to help out a friend.

 

Top View

 

Bottom View

 

Gasket Detail

 

The top view shows the BCA plate which is mounted from underneath. I chose to make the PVC plate round to better match the geography of the bucket lid. I was able to get a clean cut on the lid using nothing more complex than a pocket knife, by following the inside edge of the inner ring of the lid at a 45^o angle till it finally cut through (many passes later).

 

The bottom view shows the clear PVC adaptor in place (but not yet bolted) with a black Viton sheet gasket. I used clear PVC because it's what I have on hand (I found it when looking for gray or white PVC sheet, and the supplier made me an offer too good to pass up on the clear material). The PVC sheet is 3/8" thick (about 9.5mm). I left the clear film on the sheet to protect it from scratches till all the drilling and tapping is done.

 

The bottom view with gasket detail shows the 1/16" (about 1.6mm) thick black Viton gasket I cut from a larger sheet. I used a gasket cutter I borrowed from work for the evening (Yes, with my supervisor's blessing) and it did an excellent job of cutting the gasket cleanly.

 

I placed the adaptor on the bottom of the lid so the mounting hardware will be mounted on the outside of the cell to protect it from corrosion. I got some 10-32 stainless steel machine screws and plan to drill and tap holes part way through the adaptor, from the top, so the stainless isn't exposed to the cell liquor. The screws will go through the inside edge of the hole through the bucket lid (from the outside), then through the Viton gasket and next into the blind holes in the BCA which are tapped to accept the screw threads.

 

After I do all that, I'll finish the electrodes and populate the BCA with various fittings to accomodate the required and desired accessories to the cell. I do plan to box the cathodes around the MMO anode, for the most efficient use of the anode surface. I'm also spot-welding tubular leads to the electrodes so they can be mounted in PVDF compression fittings as Swede shows in his blogs. I'm hoping for a clean setup with no worries about salt creep or leaks.

 

I completely agree with Swede on the BCA as a simpler approach to electrochemistry. After I finish this one for my friend, I might just make one for myself .

 

WSM

[Swede]

I like it! May I suggest, after having my own troubles, to really populate that plate with a LOT of screws. Because the HDPE portion is thin and flexible, if there aren't a bunch of fasteners, you can end up with leaks between them, and the salt mist/spray from the electrode gassing is going to dump a ton of liquid near that seam. And then the internal pressure forces it right on out.

 

If you do end up with a system that simply doesn't seal well, a sacrificial bead of silicone sealant on the topside joint would work for a long time, many runs, before it'd need to be renewed, and when that happens, it should peel or scrape off with relative ease.

 

My own unit has too small a vent. When a vent is large enough, say a large bore (3/4" ID tube) or even a section of pipe, the backpressure drops dramatically, reducing salt creep. Of course if one uses a bubbler for stirring, that makes it worse.

 

Idea - since your plate is PVC, solvent-weld a 3/4" PVC pipe slip fit on the bottom side. Into that goes a stub of pipe that extends maybe 2/3 of the way into the liquor. On the top, drill and tap the PVC plate at that spot for maybe a 1/8" FPT (female pipe taper) thread, and onto that goes a pneumatic fitting, maybe just a hose barb. Attach a good aquarium pump. The air gets routed through a wide bore pipe that will hopefully never jam with xtals, as the hot electrolyte will be pumping in and out at the bottom as the bubbles escape the pipe. You could even attach a "T" or "L" at the bottom of the pipe and have a section of horizontal pipe deep in the liquor, with a bunch of holes to let the air escape over a wide area of the bucket.

 

Same deal with the acid - have a pipe (I like 3/8" amber CPVC) extend deep, with a large number of small holes in it. As the acid gets added, it flows into the pipe and then diffuses slowly through the holes into the electrolyte, avoiding chlorine gas evolution and localized pH spikes. This also prevents chlorine dioxide evolution, which can be dangerous.

 

The hard part normally is the electrode mountings through the plate, which will be solved if you go with a round-shank system. Are you going to fill the tubes with tin or lead?

 

Nice work, I'm looking forward to seeing it. If anyone is thinking about replicating some sort of a bucket cell adapter, think long and hard about the electrode mounting. If you don't have a spot welder and cannot do a round shank, you have to get imaginative with those rectangular straps, and come up with a system that is both decently rigid, AND reasonably leak and gas proof.

[Swede]

http://www.kali-gmbh.com/uken/fertiliser/products/solumop.html

 

This is excellent to know. Apparently 60% "K2O" in a muriate of potash garden fertilizer indicates a 100% KCl. It'd be wise to test dissolve a smallish portion to see if there are any insolubles in there.

[ANFO]

Can I just ask a quick question, how much, round about should I expect to pay for an MMO electrode, or how much did yours cost?

Because I've found some locally that cost between 142.44 and 213.66 dollars (rough conversion) and I'm not sure if I'm being ripped off or if they are just that expensive

[WSM]

Can I just ask a quick question, how much, round about should I expect to pay for an MMO electrode, or how much did yours cost?Because I've found some locally that cost between 142.44 and 213.66 dollars (rough conversion) and I'm not sure if I'm being ripped off or if they are just that expensive

 

Right now on eBay a fellow is offering a sheet of surplus MMO on CP titanium mesh for a tenth of that much. See item #261090740522

I believe the expense of those anodes offered where you live is due to several middlemen and processes involved.

 

The same seller (laserred) often has various sized pieces available for good prices and I recommend watching his offerings for great savings. The best use of them is to cut them down to a size that matches the output of your power supply or your poor power supply may kill itself trying to keep up with the demands of a large anode. Also, I recommend CP (commercially pure) titanium cathode material, matched to the anode for the optimal performance of the anode and a clean product.

 

If you're serious about this pursuit, study Swede's blogs and read through (all of) these posts. A wealth of knowledge and experiences are contained here, waiting to be learned...

 

WSM

Edited September 3, 2012 by WSM

[WSM]

This is excellent to know. Apparently 60% "K2O" in a muriate of potash garden fertilizer indicates a 100% KCl. It'd be wise to test dissolve a smallish portion to see if there are any insolubles in there.

 

That is good to know. Reports from users in the EU indicate that a brownish foamy scum is often related to agricultural KCl. If this is the case, I suggest dissolving it in water, filtering and recrystallizing it before use in a cell. I imagine most, if not all the problems with it will dissappear.

 

I need to see the availability of it in my area !

 

WSM

[WSM]

I like it! May I suggest, after having my own troubles, to really populate that plate with a LOT of screws. Because the HDPE portion is thin and flexible, if there aren't a bunch of fasteners, you can end up with leaks between them, and the salt mist/spray from the electrode gassing is going to dump a ton of liquid near that seam. And then the internal pressure forces it right on out.

If you do end up with a system that simply doesn't seal well, a sacrificial bead of silicone sealant on the topside joint would work for a long time, many runs, before it'd need to be renewed, and when that happens, it should peel or scrape off with relative ease.

My own unit has too small a vent. When a vent is large enough, say a large bore (3/4" ID tube) or even a section of pipe, the backpressure drops dramatically, reducing salt creep. Of course if one uses a bubbler for stirring, that makes it worse.

Idea - since your plate is PVC, solvent-weld a 3/4" PVC pipe slip fit on the bottom side. Into that goes a stub of pipe that extends maybe 2/3 of the way into the liquor. On the top, drill and tap the PVC plate at that spot for maybe a 1/8" FPT (female pipe taper) thread, and onto that goes a pneumatic fitting, maybe just a hose barb. Attach a good aquarium pump. The air gets routed through a wide bore pipe that will hopefully never jam with xtals, as the hot electrolyte will be pumping in and out at the bottom as the bubbles escape the pipe. You could even attach a "T" or "L" at the bottom of the pipe and have a section of horizontal pipe deep in the liquor, with a bunch of holes to let the air escape over a wide area of the bucket.

Same deal with the acid - have a pipe (I like 3/8" amber CPVC) extend deep, with a large number of small holes in it. As the acid gets added, it flows into the pipe and then diffuses slowly through the holes into the electrolyte, avoiding chlorine gas evolution and localized pH spikes. This also prevents chlorine dioxide evolution, which can be dangerous.

The hard part normally is the electrode mountings through the plate, which will be solved if you go with a round-shank system. Are you going to fill the tubes with tin or lead?

Nice work, I'm looking forward to seeing it. If anyone is thinking about replicating some sort of a bucket cell adapter, think long and hard about the electrode mounting. If you don't have a spot welder and cannot do a round shank, you have to get imaginative with those rectangular straps, and come up with a system that is both decently rigid, AND reasonably leak and gas proof.

 

Hi Swede,

 

All excellent suggestions; Thanks. I was wondering how many screws to use on the BCA to lid connection. It looks like I better err on the side of caution and use a lot. I'm using pan-head phillips screws, 3/8" long; and not drilling through the PVC plate (to protect the screw ends from the cell liquids).

 

I plan to fill the round shanks with 1/8" diameter, solid lead-free solder (typically 95% tin) and the 4mm ID of the tube is ideal for tapping to 10-32 with a cobalt-containing tap for titanium, so I can connect each of the power leads with a stainless machine screw and two stainless washers. I usually tap the tube ends before forming and spot-welding the other end. Next, after filling with solder, I chase the threads to clear them before putting the stainless screws in. I did this last year and had great success.

 

I'll show photos as I progress.

 

WSM

[ANFO]

Right now on eBay a fellow is offering a sheet of surplus MMO on CP titanium mesh for a tenth of that much. See item #261090740522

I believe the expense of those anodes offered where you live is due to several middlemen and processes involved.

 

The same seller (laserred) often has various sized pieces available for good prices and I recommend watching his offerings for great savings. The best use of them is to cut them down to a size that matches the output of your power supply or your poor power supply may kill itself trying to keep up with the demands of a large anode. Also, I recommend CP (commercially pure) titanium cathode material, matched to the anode for the optimal performance of the anode and a clean product.

 

If you're serious about this pursuit, study Swede's blogs and read through (all of) these posts. A wealth of knowledge and experiences are contained here, waiting to be learned...

 

WSM

 

Thanks WSM, MMO's in the post already ebay isn't usually a place I look because between postage and import tax it turns out more expensive, but not in this case, not at all. I've got some grade 4 titanium already, so that's sorted. I'm already reading through it, as well as this thread to educate myself.

[WSM]

This is excellent to know. Apparently 60% "K2O" in a muriate of potash garden fertilizer indicates a 100% KCl. It'd be wise to test dissolve a smallish portion to see if there are any insolubles in there.

 

After reading through the online literature, it appears to be 96.4% KCl but with very low insolubles. I'd like to acquire some for testing and I'll have to look in my area for it.

 

WSM

[WSM]

Thanks WSM, MMO's in the post already ebay isn't usually a place I look because between postage and import tax it turns out more expensive, but not in this case, not at all. I've got some grade 4 titanium already, so that's sorted. I'm already reading through it, as well as this thread to educate myself.

 

Excellent, let us know how it goes!

 

Do you have access to a spot-welder? Spot-welding seems to be the best way to apply leads to the electrodes, we've discovered so far. Some have had good success riviting the leads on, too; and that's an option if you can't find a place to do the spot-welding.

 

If you run into problems or challenges with the process, ask here and someone (or many) will usually offer suggestions (some of them, even helpful ).

 

WSM

[WSM]

On eBay, I picked up 50 feet total of some 4 gauge welding cable. 4 gauge is a good size, capable of 120+ amps, and more than adequate for 98% of anything we'd do. And much cheaper than the heavier stuff.

 

http://www.5bears.com/s2f/s2f032.jpg

 

http://www.5bears.com/s2f/s2f033.jpg

 

By the way, Swede, I love that red sheathed welding cable. I've only ever gotten the black sheathed and use red or black shrink tube on the ends where the terminal is swedged. I wonder how the red colored material will hold up to sunlight (whether it will fade or not)? Time and exposure will tell, I'm sure. Nice find!!!

 

WSM

[WSM]

By the way, Swede, I love that red sheathed welding cable. I've only ever gotten the black sheathed and use red or black shrink tube on the ends where the terminal is swedged. I wonder how the red colored material will hold up to sunlight (whether it will fade or not)? Time and exposure will tell, I'm sure. Nice find!!!

WSM

 

Since I was already going to the welding supply shop to exchange an acetylene bottle, and have the #2 copper terminals for #2 welding cable, plus the swedging tool to properly attach the terminals to the cable, I bought 20' of #2 welding cable to handle the larger loads of my biggest power supplies (up to 150A). I figure I can make custom cables as neccessary, as I go...

 

Since I didn't buy that sexy red sheathed cable, I'll indicate polarity by using red or black shrink tube over the barrel of the lugs as I make up the cables . Maybe I'll do it as classy as Swede does one day, but for now I'll keep doing it my way .

 

WSM

[WSM]

Since I was already going to the welding supply shop to exchange an acetylene bottle, and have the #2 copper terminals for #2 welding cable, plus the swedging tool to properly attach the terminals to the cable, I bought 20' of #2 welding cable to handle the larger loads of my biggest power supplies (up to 150A). I figure I can make custom cables as neccessary, as I go...

 

Since I didn't buy that sexy red sheathed cable, I'll indicate polarity by using red or black shrink tube over the barrel of the lugs as I make up the cables . Maybe I'll do it as classy as Swede does one day, but for now I'll keep doing it my way .

 

WSM

 

Oh yeah. Swede's right about AWG #4 welding cable being the most useful size for most of our work. I have about 50' of it already, plus termination hardware to match it. Mine is all black though, so I have to mark it for polarity (I wouldn't want to mix them up ).

 

WSM

[WSM]

Thanks WSM, MMO's in the post already ebay isn't usually a place I look because between postage and import tax it turns out more expensive, but not in this case, not at all. I've got some grade 4 titanium already, so that's sorted. I'm already reading through it, as well as this thread to educate myself.

 

Hi ANFO,

 

If you get a chance, can you take a photo of your setup and materials so we can see what you're doing? It's hard to visualize by verbal descriptions alone. Thanks.

 

WSM

Edited September 5, 2012 by WSM

[Swede]

Yeah I bumbled into the red on eBay. I thought "why not" because otherwise, you've GOT to mark those cables. I like heat shrink at the junction of the cable and lug, and you can use red heat shrink on the + cable, for example.

 

If anyone mail orders cable, two things... prices vary WILDLY, and Cu is expensive, so do a lot of comparison shopping. Secondly, and obviously, be sure it is welding cable and not regular Cu wiring, because a #4 or #2 Cu wire is going to be like a solid bar, totally inflexible.

 

I think short runs (like 3 meters) of #4 can do 80 amps continuously without getting more than slightly warm. Beyond that, or if you need a LONG run of cable, #2. I can't imagine needing anything larger unless someone is planning a 200+ amp monster.

[taiwanluthiers]

How big of a cell are you running to need 80 amps? Would it be acceptable to run multiple wires into the same terminal to maintain proper amp rating for a given cable?

 

I don't know about welding cable but I was thinking if big cables are needed air conditioning power cables are rated for a lot of amp... maybe not 80 amp but that's 3 conductors of 30 3.5mm copper wire, surely you can splice them all together to get a whopping 80 amp on one power cable... They're still fairly flexible, not as much as welding cable but flexible enough to be workable.

 

I would think you want a shorter cable run from the power supply to the cell... How do you calculate the amount of amps needed for a given cell volume? I was thinking to use a used computer power supply or laptop charger.

[pdfbq]

Aircon cables are for 110 or 220-230 V .. Say if an aircon uses 3KW on 220V it means 3000/220 =~13.5 amp for your cable (not near 80!! )

Now if you want to run your aircon on 5V ... you will need some heavy cables 3000/5 = 600 amp!

This is why the power supply cables in the air run really high voltages, means low amps.

 

For the power you have to do it the other way around.. smart WSM thinking. Adjust your anode to your power supply. A good comp power supply probably handles easy 20A.

I would try an anode of 2" x 4" for that.

Edited September 8, 2012 by pdfbq

[WSM]

Aircon cables are for 110 or 220-230 V .. Say if an aircon uses 3KW on 220V it means 3000/220 =~13.5 amp for your cable (not near 80!! )

Now if you want to run your aircon on 5V ... you will need some heavy cables 3000/5 = 600 amp!

This is why the power supply cables in the air run really high voltages, means low amps.

For the power you have to do it the other way around.. smart WSM thinking. Adjust your anode to your power supply. A good comp power supply probably handles easy 20A.

I would try an anode of 2" x 4" for that.

 

Many computer power supplies can supply 30A. If we want to take it easy on our power supply, size the anode to demand only 80% of that, or 24A. Now the most efficient setup is two cathode plates surrounding the anode plate. I figure a setup like that would use an anode 1.5" x 4".

 

1) 1.5" x 4" = 6"²

2) 6"² x 2 = 12"²

3) 12"² = 77.4cm²

4) 77.4cm² x 0.3A/cm² = 23.22A

 

Step one finds the square inches of the anode

Step two shows the average total surface area of the anode (two times the single side surface area; omit this step if only one cathode is used)

Step three converts the square inches to square centimeters (a ratio of 1 to 6.45)

Step four multiplies the surface area in cm² by the average current per cm² (which is 0.3A) and yields the total expected current demand of 23.22 Amps.

 

I use this formula all the time to calculate the total current demand of any MMO anode, and so far it holds true.

 

Now if your power supply is rated to 30A (which would call for AWG 10 gage wire) and all you have is finer wire, just multiply the number of wires used till the required cross section for the current demand is met. Basically, the voltage carried determines the insulation thickness, the current carried determines the conductor cross section.

 

WSM