Do you know how the Safe Current level was set? A certain max temperature?
I think use the same thermal benchmark as you do for cells, ideally we get a voltage drop per multimeter per amp rating and a overheat current at like 40V
Edit: so no air flow, most wires are tightly packed in enclosures and the nickel is under layers of fish paper and shrink wrap
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It seems so, because columns are good/warm/hot.
It would be cool to know the temperature threshold for “good” ampacity
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I’m confused…40V? The voltage wouldn’t have an impact on the strip heating.
That is what I’ve been spending some time considering…how to replicate this in testing. Not only are the wires and strip buried in the pack but you have the cells possibly raising the “ambient” temperature some too. This can probably be ignored but I want to at least consider it.
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I suppose so, heat output is always current squared times resistance
The newest numbers were edited upward from the old ones, based on this empirical test that @mutantbass found
and beyond that, they are all ratios based on conductor cross-section, so for example a 0.15mm x 12mm strip would have 150% the cross-sectional area of a 0.15mm x 8mm strip. (1.8mm² vs 1.2mm²)
The more information, the better. Testing with dummy cells wired inside a fake pack would be even better.
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Agreed. Most of the numbers are based on extrapolating from a small number of tests. Probably good enough for many but there can always be surprises when not accounting for all the variables.
Problem is, variables add lots of time and grief to the testing. 
I think it can be divided into one small set of very “realistic” tests to quantify the effects of ambient temperature, heavy gauge wiring sinking away heat, spot weld heat, etc. Then do simplified testing of all the strips/wires and apply the offset established in the “realistic” tests to arrive at the final numbers.
The results should be fairly close to the actual temperatures seen in use but, more importantly, the numbers would allow direct comparison of the performance of the different choices for cell interconnects. Any particular person might see higher or lower temps, based on their particular setup, but the differences between the interconnects should be pretty much the same for all as long as the pack is constructed about the same way.
My approach is going to be based mostly on performance rather than just temperature. My thinking is that as long as the temp isn’t high enough to damage cells, soften wire insulation (if PVC), or split shrink wrap, then the temp can be ignored.
What I want to quantify is the voltage drop/power loss for the various interconnects and to make it easy for pack builders to decide what interconnect they will use.
Is a Cu/Ni sandwich worth the spot welding grief?
What is the actual improvement in performance when doubling up on Ni strips?
What strip widths are actually needed to avoid excessive power loss?
How many spot welds are actually needed for different current levels?
I suspect that the power losses will be unacceptable long before the temperature gets too high. We’ll see if that’s true or not. 
Also heat-related stuff like…
How hot do the spot welds get? Do they heat the strip or is it just heating from ohmic resistance of the strip?
How much do the soldered on wire leads (if large enough) cool shorter strip lengths?
How much does the temp of the cells affect strip temp?
Showing that wire length has no effect on wire temp (as long as the ends are not being cooled by whatever the wire is being connected to).
Stuff like that.
It will all get boiled down to a very simple table but the more data that is gathered the more accurate and useful the table can be.
I need to find empty assembled 18650 cans to create packs with. Fogstar in the UK sells them but I’m hoping I can buy a bunch from someone here.
Looking forward to your thoughts regarding the “realistic” testing and where the temperature and performance thresholds should be!
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I’ve wondered this many times.
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Haven’t measured that, but their power loss should be very low. They have a smaller cross section (maybe 1mm diameter), but they are also very short (maybe 0.1mm) and therefore don’t have much resistance. With these numbers and pure nickel, you’d end up with R = 7e-2 * 0.1e-3 / (PI * 1 ^2 / 4) = 8.9 microOhms per weld.
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Thanks! Makes sense that the resistance of the metal would be extremely low.
But can we always assume zero ohm connection resistances to the cell (only referring to good welds)?
I ask because a single weld at 8.9uOhms would have a voltage drop of only 267uV at 30A and a power loss of about 8mW. We’d only need a single spot weld for just about any cell connection.
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Good question, but I think that it is safe to say that a weld that sticks (causes nickel strip to tear apart when pulling) will also be more or less be solid metal. I’m not a spot welding mass production expert myself, but it is my understanding that you make multiple spot welds for extra rigidity, and to cover situations where a bad weld is overlooked.
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The one at the top here is the most up to date one. At this point in time it’s got 14 edits
If you have any test results, let us know so we can take those data into account as well.
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I would love to but unfortunately I don’t have the means to 
On another note, I don’t see any listing for 0.2mm x 10mm nickel; are there any estimates as of yet?
added
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Just wanted to show appreciation to the keywords here. Search on this forum is so shit, so this really helps.
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So how would Stranded Copper Silver coated wire compare for use from ESC to Motor (phase wires only)
provided Cable flex is not and issue this should in turn result in less heat to the motor (though the motor is still copper wound)
Silver coated copper won’t help much, if any. Copper coated silver wire would help, but the amount of help would probably be marginal at best.
It’d be better if the windings were silver instead of the phase wires, because that’s where the heat gets trapped more. The phase wires don’t overheat as much as they have a lot more airflow.
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In my case there’s nearly no airflow for the phase wires, so just looking at it from scientific vs pratical for now.
Copper Coated Silver exsists heh?
And pure Silver stranded? (aware it needs somethig to prevent degrading) - Marginal gains are fine - been long term doing marginal gains thruout mysetup over time it’s not so marginal anymore when all added up.
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