Well played sir. Well played.
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The thing with cutting corners is that you don’t want the nickel to bend in the gap between the positive terminal and the negative body. So either you cut the nickel to finish at the round of the positive terminal or you let the nickel long enough to lay on the outer ring of the cell. Like here it’s not that good
In this case how you did it on the cell above would be better.
One tip to not short anything while welding, cover all parts you not work on with masking tape. For example
Even there I could have covered the row I don’t work on, but as it was the first row I did it wasn’t a big problem.
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Okay, that makes sense. The masking tape was something I did not think of, will do that when working on the other 5s2p of the battery. I see you also have the correct way of the H-shaped nickel. But I still do not understand why it performs better that way then the way I did on my first picture 
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I don’t get that as well. This H shaped nickel is 7mm wide in each direction. You can cut it the one or the other way in your case it shouldn’t make a difference.
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Ok, its time for me to chime in on this excellent thread, we have been working on some big battery packs and have some excellent results.
The Falcon evo, 12s6p sanyo 20700c 30a cells in a eboosted enclosure
on a D124 12s bms set up for quad, built to pump out amps.
Recent LaCroix battery upgrade 12s5p sanyo 20700c 30a cells (not performed by LaCroix or any affiliate of, from, or henceforth referenced in the said thread) disclaimer…
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Surely no decent amount of amps will go quietly through this dinky strip on the positive side
https://esk8-news-objects.s3.dualstack.us-east-1.amazonaws.com/uploads/original/2X/c/c9d81e37beeb2d2de571460cadf2e96e7ba16e8b.jpeg
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Isnt the "dinky strip "sposta be cell level fusing. I think lookin at it thats the idea
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Why do we fuse the positive terminal? Shouldn’t the end with both contacts have the stronger nickel?
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I never understood cell level fusing. It seems synonymous with crappy conductivity. If the goal is to break the series connection all the four cells would have to burn through their nickel. What temp would be necessary for that and will the cells actually get it that hot? All the while will be pumping amps and from what I’ve heard a dead short will send a 30q into runaway instantly.
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Its a lot less work/space/cost than thermal or currently triggered breakers, and it’s a decent defence from the whole pack exploding
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Will it stop the pack exploding though as it would have to short likely for awhile to burn through that nickel and by that point maybe in flames already.
Maybe the heat from the lame strip could even be a problem melting insulation or something. It’s so thin maybe the few welds would pop off. That nickel is good for maybe ten amps max even if .2mm thick.
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Personally I’d rather see a new generation of BMS designs with adjustable shut down currents and daisy chain temperature fuses on PCBs but that will cost a lot more so it won’t happen for a while…someone has to design and make them and I have no idea where to begin
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The temp sensors would be nice and maybe could be pretty cheap and easy but I don’t think anything will stop a fire if 30Qs burst in flames at the initial short. Tempted to dead short one just to see but I’ve heard from two people who shorted them and instant Roman candle
To me that pic above with the tiny strip looks hella dangerous.
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If you special design the pack, you can build it to eject the parallel packs if a temp sensor fires. If there is a divide between the parallel packs like on segmented enclosure then there would be minimal heat transfer to rest of the battery. Catch is you’d need electronics and a servo/solenoid/detonation bolt to open the enclosure and a plug that will release cleanly but still have a solid connection. Thats HELLA work though
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the DieBieMS has 2 temp sensors on it and the overall unit works well for lower Amps (up to 100a) I like the setup, the flexi bms lite mini has more of what’s needed and less bulk because it’s not discharging through the bms. The size of the latest version is perfect for any pack.
Flexi lite ( still in development )
A DieBieMS with a 12s6p sanyo 20700c quad (duel) unity
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@hyperion1 is there a reason why there is no fishpaper under ther balance wires
How you protect the balance wires in the middle of the pack to rub against the cells? There is some kind of spacer?
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I would place one. Silicon can rub off over time. Ask @b264 about damaged silicone wires due to vibration. For sure it also depend if there is a force on it somehow beause of less space or just accidently. that fishpaper stripe is like 0.002 cent and takes not longer than 20seconds to put it there, so why not just to add it.
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Plastic rubs off more, but silicone also can with enough vibration. Silicon is hard like glass and isn’t used for wire insulation.
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