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Yes, thanks, good point. Perhaps I should split one open and insert a thermocouple in the center of the pack and seal it back up to see what is really going on.

Thank you!

thx :)

Very cool info. I did cut and sand it down and placed it in a salt bath to check for corrosion but I like your method! Saving it for later.

Thanks, I mostly test to collect data for builds I am planning and a video is a nice way to share the data.

Yes, that is something I should also test. I was planning to get an Infrared camera so I could monitor hot spots, typically the hottest places should be right at the spot welds. So what would be the effect of doubling up the nickel strip? Nickel plated copper would be ideal, and since copper has excellent thermal conductivity it could also carry heat away from the hot spots where it is welded to the 18650 cell, assuming that is the true hot spot.

LOL yes, I did do it with no fan and constant fan, since I took each temp reading after it reached steady state temperature the results were the same for no fan. I planned a much longer video where I correlated the results with a thermal simulation in CAD but I got too busy and just called it, and posted what I had :)

Thank you!

Great question! I did not measure that :( however I am sure it could be estimated with the dimensions and resistive value of nickel.

@@mechanicalgraffiti same way you could estimate temperature. But you did test to prove it.

Yes if I do it again I will check voltage but I may not be using nickel on the next setup planning to switch to aluminum or coper for my busbar . Temperature is much harder to calculate, you need to know the heat transfer coefficient (h), and that is a hard number to get. Originally, I was correlating the test to a SolidWorks simulation to derive my h value but I ran out of time and no longer have access to thermal simulation.

Thx

Thx

Yes the Zeee and Turnigy were basically the same size, I think I looked for a 1000 mah Zeee and 1400 was all they had.

thx

Are you using cylindrical or LiPo pouch cells? And yes copper is much better, the OEM power tool battery I took apart used used nickel plated coper, great conductor with no corrosion.

@@mechanicalgraffiti molicel P42A, 21700 Li-ion. I have a 8" by 8" plate of 1mm copper that I'm going to cut into strips for this. Might add a couple of grams, but I did a bunch of math tonight, and this 1mm copper has 42x less heat generation than these little .1mm nickel strips at 30+ amps (all else being equal). Heat being an exponential function of current really makes copper mandatory for anything over 20A, even stacking 4 or 5 strips doesn't come close... About everything fun in the R/C world rips more than 20A... Mine are going in a dual EDF jet that can pull 120A easily. These molicel are badass, though... Much lighter than lipos for the equivalent Wh rating... But some lipos can make much more current for their size... Hence my need of a 3p config.

Dual EDF sounds awesome. And yes copper is amazing, 1mm may be overkill, you probably don’t need anything thicker than the thickness of the positive terminal on the battery and be careful soldering, the heat can damage the cells. You may be able to get some copper shim stock that could be doubled up and spot welded on the cheap. I just finished editing some old footage on high amp rated 18650 and 21700 cells and published, although they are still nowhere in comparison to LiPo pack in terms of power output, see my Zeee vs Turnigy test.

With 14s the current will have to flow through each connection made in series, how many in parallel do you have, typically that is how the current will split, there will be some bias to the path of least resistance but that should be a small fraction of the total current. It should split relatively evenly across all cells/connections in parallel.

@@mechanicalgraffitiThanks a lot buddy , i was reallly getting confused

Thanks, Yes the equipment came from industrial auction site www.go-dove.com, I have video for Sony 21700 cells and more 18650 but have not had time to cut and upload. Any batteries in mind I should test?

I would like to see how similar batteries from a single manufacturer stand up to each other. Like zeee 50c vs 80c vs 100c vs premium. Or turnigy plain 25c vs HD vs graphite vs rapid, etc. I use car packs in the 2S/3S 5000maH range. Common with the car/truck community. My thoughts would be regardless of what battery you test, standardize your C discharge rates so that at any point you can compare to any other cell you have done before. I'd like to see cells at 10C, 25C, maybe a bit lower or a bit higher as that is closer to the range most people will see. But understand for sure that more tests equal more time. What interests you?

I see, yes, I could do some testing in that range, my electronic load is limited to 1000 watts so at 3s (12.6v) and 5000 mAh I could do (12.6v*5a=63w, 1000w/63w=15.8C) 15 C max. Actual test time is no issue, setup and video is the majority of the effort. I am interested in absolute max power draw and associated voltage drop, which affects motor speed. I was working on a quad motor super kart that could take me from 0 to 60 sub one second. For that I need precise load measurements that I could scale up to 160 kW total power, plus a 20 kW ducted fan to suck the cart to the ground to get the necessary ground effects to accelerate at sustained 3g for one second. For now it is all on hold as I am looking to make a Solar Cannonball Run attempt soon. Do you have any LiPo batteries suggestions, best brands to look at?

@@mechanicalgraffiti Is 180KW (160+20) for 1sec the goal for the kart? Do you have a voltage target for the power system? Awesome sounding project either way :D RC packs are a great way to get what you need in KW and cost. Turnigy has usually been my inexpensive go-to as I have had some ~5AH packs last over 10 years, and the cell ohm (iR) matching is much better than Zeee. Which on that note, have you done any iR measurements? That seems to be everyone's go-to on pack comparisons, all else being equal.

Yep 180 kw total power. I want to go as high a voltage as possible, the limiting factor are my 5 ESCs at 85 Volts, one for each motor and the fan. I have not done any internal resistance measurements. I was looking at using 28 liPos each a 4S 9000 mAh. I have most of it modeled up in SolidWorks and a huge excel sheet with all my calculations. Maybe I should make some videos of it. I am at the point where I may need to open source the project, I do not have the time or money and progress is stalling out.

Thanks, I did not mention at the end of the video you can see the tape blistered, creating an insulating air pocket, resulting is higher than expected temperatures when correlated with SolidWorks thermal simulation, but in the end I just cut the video, since I sat on it for year waiting to complete.

@@mechanicalgraffiti - Your test is in air, not on a battery cell. The proximity to the batteries and not hanging out in the air will also affect the results. However, I think this is beyond the scope of your test here. You didn't tell people how much it can take, but instead showed them the properties of it and how it reacts to higher currents to let people decide for themselves. Most people who are assembling these are fairly technical people and can make the judgement of what is best for them. The reason I watched your video is that I am making an electric motorcycle. Based on your results, my 10X0.15mm strips can handle 35 Amps maximum for extended periods of time. I am basing this on your 6.88mm wide strip temperature at 25 Amps. Now I know how many strips to use. Thank you.

Pure nickel, I even cut and sanded sections in a salt bath to check for corrosion, so should be pure as advertised.

Glad I could be of service

Thanks, I tested some Sony/Murata 18650 and 21700 cells and just need to edit all the footage. As far as 18650s go they took the cake. I also have some heat pipes that need testing and dissecting.

Thanks, a little enginerding goes a long way.

What in the hell does a weed smoker have anything to do with the ability to gather accurate data? Your slapping a stereotype on something you don't understand.

Glad I could help

Nice, you will have to let me know how it goes. Next I plan to current test nickel strip to see where the limit is. What controller do you plan to use?

LOL, that's what AvE would have said, and then something about a vise.

Well it is a long video :)