I have been wondering about this also, and I am not going to be able to fully explain the issue, so will just convey some observations.
It hasn’t seemed to give us any trouble that I know of in results or consistency. We usually don’t anodize part loads this small, and I just “mocked” these up for illustration. However, on the finger rack that has the smaller washers we run parts that aren’t in the picture with theoretical current requirements that range from .0179 - .5664 amps for each part at 8 amps CD. Since the resolution on the power supply is only .1 amps we do try to run total loads of at least 2.5 amps to try and minimize the error some. But even then the surface area of the rack is much larger than the combined parts.
They still seem to anodize consistently though with larger parts and loads using upwards of 20 amps. I can’t explain why the rack surface area doesn’t seem to show up as a problem. Perhaps there is room for improvement though, by learning more about it and maybe factoring the relationship of part area versus rack area into some kind of current adjusting formula.
I do know that the titanium racks make the actual voltage inconsistent with your numbers. For example, when the total part load is small due to small parts, the voltage will be lower than expected, I suppose due to the fact the resistance of the rack is fairly low. If the parts are larger, it draws more voltage at the same CD. I have varied the depth that the racks are submerged and watched the voltage go up and down. PAR is shown, just not necessarily at the voltage expected. That is probably why, (if you remember sometime back) that some voltage peaks we see were low indicating low ohms.
I really don’t have any conclusive answers, although I would like to understand it better myself. Since you appear to enjoy experimenting and understand the electrical aspects, I was wondering if I sent you some titanium racking if you would be interested in playing around with it and perhaps come to some conclusions? If you are interested let me know, and I will some to you.
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