Does size matter?

[VanHalen]

This may have been covered in a another thread but I hadn't seen it. So I was thinking, does the size of the plate ie. 8x8 or 4x4 affect MMW or effeciency loss? It seems to me most people are using larger plates, but if you could use the same amount of surface area in more plates, wouldn't you increase effeciency? For example instead of 7 8x8 plates for a total 448 sq in of surface area, what about 28 4x4 plates for the same amount of surface area? Looking at some of my past cells, the middle seems to darken before the edges. Maybe my cells just suck(very possible), but maybe the current isn't as strong as it reaches the edges, eliminating usable surface area?

[redneck323]

Ok heres my absolutely non professional non experienced opinion. From what i have been told it is best to have 4 sq in of plate area per watt. If you dont know wattage is volts x amps so as long as you have the supporting surface area. This area is active area so a neutral plate 1in x 1in would be 2 in of surface area as neutrals act as positive on one side and negative on the other. As far as the middle darkening before the edges i believe that is the area that is supporting more electrolysis(or current leakage). I would venture to say that your connections are in the center as well. I wonder if we should be making 4 point connections on these cells(all 4 corners) due to the high resistance of stainless even if no traces of current leakage are evident that may increase efficency especially on larger cell plates.

[VanHalen]

Actually my connections were on the top of the plates. So if your not drawing enough amps to suffice for SA your actually losing efficiency?(assuming a seven series plate cell)

[redneck323]

Thats a good question. I dont know if you would lose efficency do to lack of wattage per surface area i would venture to say that you wouldn't but i do not know. My plan is to target a certain (maximum but safe amp draw) for my vehicle and build a cell accordingly. I am targeting 1440 sq in to support 30 amps at 12 volts. If you had a choice i would say build it too big rather than too small.

[Painless]

Personally, I prefer the "more plates providing the same surface area" approach. The bigger the plate is, the more encouragement the current has to take a short cut through a limited section of the plate, wasting surface area.

[redneck323]

Yea good thought. Since the stainless has poor conductivity it would be better to go with more smaller plates... but i wonder what connections on all 4 corners of each plate would do for this maybe equilize the current flow more so, since you would have more connection points to cut down the distance the current has to flow through the plate.

[VanHalen]

I agree with painless, we don't need to encourage any current leap lol, and it just seems to me that smaller plates would work better because of the full use of each plate. I do like the four point connection idea. My plates are on the way(I think), maybe I'll give this four point connection a go on my next dry cell.