Bump @chaka thanks
We cut them from nickel strips.
If you build a pack like this be sure the buss bars are insulated from the cells. Before 3d printing holders used fishpaper for this.
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Iām a bit confused maybe on the gauges needed in these packs. Iām building a 10s4p pack right now from LG HE2 cells and according to their rating, I can do 20 amps per cell. I plan on drawing up to 80 amps (probably a bit lower to lower the sag). From researching many charts, it seems like 10 gauge can do 80 amps without too much heat, 8 gauge can do 100 amps with little heat. Should I be using 8 (or 10) gauge wire (or stripping equal to 8/10 gauge) through out the entire pack? You say 20 amp fuses, but none of us are pulling only 20 amps as a max. I think my image of how the electricity flows in a battery pack might be wrong.
cells in parallel share the load
if you are using he2 cells in a 10s4p pack, each cell will provide 20a continuous (total of 80a) when needed, so 20a fuses on each cell are fine (if you draw more, it is unhealthy for the battery, and the fuses will burn to protect your cells).
Remember this is a precausumary method the lg hg2 can discharge 20A constant and 30A burst. So you will want your fuse to be for 35amps other wise youāll be blowing fuses within the normal operational range of the battery.
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Those ratings are for open air, these fuses are attached to infinite heat sinks so they will handle higher currents than those spec sheets state. If the fuse is too large then you can still get a thermal runaway.
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One important thing to consider is the heat wasting part of this arrangement should be as small as possible. Thatās why you see that the fuse box is cars have such small fuse element. Hereās my analysis.
For this analysis we consider that thick wires have 0 Ohms per cm and the fuse wire have resistance r Ohms per cm. Heat energy wasted per unit time I^2*R (I: current R: total resistance).
Say you pick 2 fuse wire with the same Ohms per cm (1ohm/cm) and both melt when 5 A current passes through them. However one is 2 cm long and the other 1 cm long. You will see that they both work when passing under 5A of current and both burnout at more than 5A, however the heat wasted through 1st one is 5(A)*5(A)*1(ohm/cm)*2(cm)=50Watts where as the 2nd one wastes 5(A)*5(A)*1(ohm/cm)*1(cm)=25Watts.
So basically if you want to not wasted your precious battery capacity as heat, use small length fuse wire.
If I were to design my own battery pack, I would try to integrate the car fuses. They are easy to replace, safe(enclosed) and very cheap. You can get a 20Amp one from here for $0.13
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The design I have works very well and the fuses do not get hot under heavy discharge. Real world testing has always given me the best results vs speculation. I have been working on this design for nearly a year. 
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Thanks for sharing this info to the community @Chaka! Really elegant design and execution it seems. The part i want to confirm here is how do you connect fuse wire to the cell top? Is it just left pressing against the flat/button top of the cell, or soldered? And the fuse wire to the back of the nickel bar - assuming itās held in place with solder?
Iām still trying to figure out how to wire these for balance charging - any completed pack before shrink wrap to reference?
Do you sell just the 18650 holders by chance?
Over a year on the designā¦ damn man - thanks for your insight and giving back to the community! Saves us a ton of time figuring it out ourselvesā¦
Iāll post some photos soon of the completed pack, it should be clear once you see the details. I need to finish another project before I can clear our battery assembly area and build more packs. Never enough space!
If you have your 3d printer up and running I can share my stl files with you.
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This is awesome. 
Just freaking awesomeā¦ This is clearly going to be the new standard of excellence.
@chaka Thank you so very much for sharing your design! Those cell holders are over the top. Too cool.
I have a quick question about the nickel strips that you are using. Why are you not just soldering the fuse wires to the cells? Is it so that you can have a tab to solder to that isnāt directly on the cell? For ease of maintenance?
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Uploaded the latest .stl files to Thingiverse: http://www.thingiverse.com/thing:1712459
If anyone needs a lower or higher number of cells in parallel let me know and I will put it on my list of things to do.
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3 cells in parallel would be nice.
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4p would be awesome too 
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Thanks so much for sharing this @chaka! The question this leaves me asking is how likely thermal runaway is with the commom cells that we see in use right now (18650)? What has to happen to push these cells to this point? Assuming they are authentic cells and that they wired and charged properly, is the risk great enough to warrant the additional complexity of the battery build?
I agree that this might become a new standard for esk8 and I fully appreciate that youāve shared your design, itās an earnest expression of your commitment to open-source thinking!
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While I canāt answer most of your questions I can chime in on a few things. One advantage of fuse wires is that, if youāre soldering your cells, using fuse wires makes the process much easier and is better for your battery as opposed to trying to solder thicker wire directly to the cells as less heat is involved. Iāve had a couple of fuses break on two occasions while Iāve been riding due to riding on extremely rough roads with really hard wheels and the fact that my current battery pack needs to be redesigned as itās been a temporary build while Iām working on a modular design for taking my board on planes. In my case I have a 10s4p pack with two fuse wires breaking on a single 4p pack and it had no noticeable effect on the battery in the short period that I rode it afterwards. As long as you have enough cells in each parallel pack to handle the current then I donāt think it should really be an issue, at least for short term use. I only realised what had happened after plugging my board in to charge and finding that I wasnāt able to fully charge my board.
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Fuse wire failed due to vibration?
More that the hot glue holding the cells together came unstuck due to vibration, allowing the cells to move about a bit and eventually break the fuse wires. When the cells are properly secured this should never really be an issue.
Okay I might do the fuse wire for my next build with the cells stuck to the board with double side tape