Brown sludge/filter/diff electrolyte??

[jcbarton]

I have a 7 cup cell. The cups are SS but not a good quality. I know that I need 304 or even better 316L steel to prevent the oxidation of the metal and the electrolyte. My problem is that I do not have access to these materials in central america where I live. Has anyone had any luck with installing some type of in-line filter to help clean out the rust? I was thinking of maybe a pool filter but would like some feedback before I waste more $$. Or maybe a different electrolyte?? I use 100% KOH. I am switching to a dry cell as soon as I can find a quality supplier but I need to solve this problem before I move on to the dry cell. I have a small surplus of the cup cells.. :( frustrated and needing help, thanks!

[Painless]

If you're using KOH and distilled water as your electrolyte, you shouldn't be having constant issues with rust flakes. I've built my cells out of 304 since day one and only get the rust issue during the burn in period.

If you could provide some more details, such as the rough surface area in your cell, gap size and kind of volts / amps you're putting through it I should be able to give you a better analysis of which way to go.

Russ.

[jcbarton]

My 7 cup stacked cell has a gap of about 1/8 (approximate) of an inch between cups. They are -NN+NN-. I am using a food grade SS cup (not 304-made in china :( ). The KOH flakes I am using is suppose to be 100% -1 teaspoon per gallon (bought in central america). Cold start about 8 amps and gets to about 20 amps when it heats up (maybe in 30 mins). I use distilled water but again it is bought here in central america so I cannot guarantee the quality. Huge amounts of brown sludge after about a week of running it.

[jcbarton]

Sorry, the volts are about 13.8, approx. The surface area I am not sure about but they are the same SS cups that a lot of people were using for a while. They are about a 2oz size, not sure about the surface area. I can send you a pic later tonight to your email address or how do i attach a photo here??

[Painless]

Ok, 13.8v with only two neutrals is a major cause of your issue. Over voltage per cell gap has always caused big time leakage and brown sludge for me.

Remove the centre positive connection and make that cup a neutral, then connect the positive in place of one of the end negatives.

If you find this gives you too much of a production drop, bring your cups closer. 1/16th of an inch or less would be ideal for a small cell like this.

Hope this helps!

Russ.

P.S. best way to do photos is to upload them to a flickr.com account and use their embed code.

[jcbarton]

Thanks a lot painless, will do. I will post the results asap.

[mytoyotasucks]

if it is rust u are getting, the stainless might be plated stainless steel, not real stainless. not sure about brown sludge.

Painless - can u explain more about brown sludge?

[Painless]

if it is rust u are getting, the stainless might be plated stainless steel, not real stainless. not sure about brown sludge.

Painless - can u explain more about brown sludge?

Over voltage per plate gap and too close a gap is what tends to cause it, in my experience, especially with the lower grades of stainless. From what I can see, the metal leaches brown particles (oxidised carbon?) which make a lovely brown sludgy soup.

[jcbarton]

I was told my the guy who built my cells that if I switch the power leads which would make it a +NN-NN+ instead of the opposite that this should help with the current leakage and the over voltage per plate. What do you think? I know you have experimented a lot with the plate configurations. Its a pain in the A$$ to take the cells apart, re-configure and then re-seal..

[Painless]

I was told my the guy who built my cells that if I switch the power leads which would make it a +NN-NN+ instead of the opposite that this should help with the current leakage and the over voltage per plate. What do you think? I know you have experimented a lot with the plate configurations. Its a pain in the A$$ to take the cells apart, re-configure and then re-seal..

Simply switching the positive and negative terminals will make zero difference.

Following the advice in my first post of this thread will be your best bet.

Russ.