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Thread: Dramatic Current Drop When Current Flow Reversed

  1. Default Dramatic Current Drop When Current Flow Reversed

    I just discovered something which I completely do not understand and was wondering if anyone knows the explanation for this phenomenon or has seen it themselves. When I reverse the voltage across my dry cell, the current draw is half of what it was in the normal direction. It's as if the plates allow the current to flow in one direction more than the other. I'm guessing whatever direction the cell was originally run at becomes the least resistance path, but don't understand the physics of why that would happen.

    This leads to another problem I recently started having. When I originally built my cell, it worked great and current, voltage and gas output values were as expected. But then after taking the cell apart several times and expanding it's size, I can no longer get it to draw the same current as before. Since I was not aware of the above phenomenon, I did not take care to keep the plates in their original order and they got shuffled around. So I'm guessing some of them are reversed and adding more resistance to the current path than they originally were. Since I wiped the slight rust colored stain off the positive sides I no longer have a visual cue as to what the original plate orientation was. Is there any other way to tell, or will the new orientation eventually "burn in" after some time and get back to the original resistance values?

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    Default Others have run into this phenomenon.

    Quote Originally Posted by Pyronaught View Post
    I just discovered something which I completely do not understand and was wondering if anyone knows the explanation for this phenomenon or has seen it themselves. When I reverse the voltage across my dry cell, the current draw is half of what it was in the normal direction. It's as if the plates allow the current to flow in one direction more than the other. I'm guessing whatever direction the cell was originally run at becomes the least resistance path, but don't understand the physics of why that would happen.

    This leads to another problem I recently started having. When I originally built my cell, it worked great and current, voltage and gas output values were as expected. But then after taking the cell apart several times and expanding it's size, I can no longer get it to draw the same current as before. Since I was not aware of the above phenomenon, I did not take care to keep the plates in their original order and they got shuffled around. So I'm guessing some of them are reversed and adding more resistance to the current path than they originally were. Since I wiped the slight rust colored stain off the positive sides I no longer have a visual cue as to what the original plate orientation was. Is there any other way to tell, or will the new orientation eventually "burn in" after some time and get back to the original resistance values?
    Your conclusions are probably correct for the current density and stainless alloy you are using. An iron rod in an electric field becomes bi-polar (magnetic) over a period of time. The same is true for many SS alloys.

    I use common 303/304 SS but run low current densities through them. I also use tubular electrode configurations and as such, I don't see the polarization problems you have observed.

    As to losing production as you have expanded your generator cell count, remember, at some point, that the voltage per cell can drop below the Faraday limit for the cell and production will drop drastically. You will have to split your arrangement to include two parallel units.

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