brilliant thank you
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I’m planning on running a 50° front/30° rear setup on an LY Evo 40” for a lot of stability but a solid amount of turning ability, does anyone else run an evo and have any suggestions for split angles? Using TB110s and BN M1s for reference
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I humbly disagree.
If one cell develops an internal short and starts drawing current from the other cells in the p-group then having more cells will results in less current current being drawn from each cell, reducing the chance of the other cells going into runaway (solely from excessive current draw).
If you had a 6P group and one cell started drawing 100A then the other five cells would roughly divide that into 20A/cell. Easily handled by even 10A rated cells without going into runaway.
However, if you had a 2P pack and one cell failed and started drawing 100A then the other cell would have 100A drawn from it. This on its own may or may not force that cell into runway but being next to the first cell already in runaway means both cells can get frakkin’ hot and that could force the second cell into runaway too.
IMO, a cell that fails won’t be drawing huge amounts of current though.
If it develops an hard internal short circuit then it will self-discharge quickly and start drawing current from the other cells in the p-group. But the current will be limited by the internal resistance of the other cells and the resistance of the cell interconnects. I don’t think that will result in enough current to force even a single cell into runaway. Perhaps I am wrong though so I’d be interested in seeing any academic/industry papers discussing this if you had links.
IMO, the failure of other cells in a pack, after one cell fails, is due to that first cell bringing other nearby cells up to the runaway threshold temperature. Not from too much current being drawn from the other cells. Especially since the current is divided by the other cells.
More BMS’ and more wiring can lead to a less reliable pack overall and invites other failure modes. There might be some scenarios where individual strings of cells are separately managed and then paralleled but that kind of configuration is rare, if practically non-existent, in commercial packs.
I see a couple of issues…
Covering cells in that material would be quite expensive and force the builder to wait until it set. Those materials are also not nearly as abrasion-resistant as fishpaper.
Using the spacers and silicone also increases the size of the pack.
There might be some setups that could benefit from using plastic spacers and a thermally-conductive insulating coating but I’m not sure an esk8 pack is one of those.
It’s always good to think about alternatives though instead of just blindly accepting how others are building their packs IMO. Most things are done by most builders for very good reasons but that doesn’t mean everything they do for their packs is the best for your setup. 
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Do you have any links handy?
Pardon my ignorance…”CLF”?
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He mentioned it earlier. Cell level fusing. We don’t do it much here because of the complexity and extra space requirement.
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this is the best reply ever
thank you and appreciate your time indeed
i love challenges and thinking out of the box even if smth ideas may sounds silly
thank you
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let me check battery build block in this forum
Arrgghhh…my apologies, I missed that when reading through. Thanks!
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Ah I wasn’t sure which kind you were talking about.
I haven’t personally seen any diagonal ones though and most people use the diagonal arrangement in our builds because you can fit more cells in the space. Every once in a while people with 8p packs or mountainboard packs do them in the square config though
understand but i guess the idea is there and how do we cut plate is just technicality rather than obstacle
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this is interacting how big difference makes 1mm extra spacing between cells
this is from nasa.gov
im still looking for write up about P section ( more cells more fire )
i was reading today whole day from multiple sources taking notes
and it is now 2am in London so i may postpone it — but i will find eventually
look at the 45-55 degree to compare as there is one with 20 degree - which you may not have inside enclosure when riding ( unless you have some fancy cooling system )
I’m not sure we can conclude that jist the 0.5mm extra cell spacing (not 1mm) in those tests made a difference.
Those tests indicate to me that the 25°C-30°C ambient temperature difference between some tests mattered as much, if not more, than the spacing.
I agree that spacing cells further out has to make a difference but I’m just not sure that a 0.5mm difference means a lot. That is a verrrrrry small difference. 
I would have loved those tests to have been repeated with several packs.
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Wait…so that table you posted was for testing with their insulator material in place? That changes everything. We can’t draw any conclusions from it unless we are using their material.
We have to be careful when generalizing from data in corporate presentations.
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lol nail penetration? if shit get to that point, its pretty much unsaveable
also was this test result done in a simlulated space environment? if yes, then the vacuum alone would help just by moving 0.5mm away from each other, but who would have that kind of tech built into our esk8?
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the bottom line the temperature is battery enemy
and i can see packs built mostly without taking this into consideration – please dont take me wrong
or maybe with boards this factor is insignificant and there is no point to talk about it
it is very hard to find pack with heat-sink – it should not be difficult to implement and should not take too much internal space ( since heatsink has to be exposed to outside ) – yes understand waterproofing etc.
Do we actually need to think about temperature dissipation or not
motors getting bigger and bigger and we want more power and more from small package factor
hmmmm
and i can see packs built mostly without taking this into consideration – so much insulation
very often one can find foam sheet wrapped it helps with impact but do we need to wrap all pack with it
layers of fish paper – electrical insulation – obvious – but not always a lot means better
please bear in mind im not making any claims or statements
im hear to listen to and learn from more experience builders