Well, one of the main tests for any given pack is that if one cell has a thermal runaway, it should not combust the others. Only way to prevent that is to make it vent in a good way, covering the vent is not that way xD
Test is basically wrapping one cell with a heating conductor and bringing it to a flaming 150+ Celsius and see how the pack holds up.
Heres an example(porn) of a pack that passes that destruction test:
Itâs an unbelievably bad idea, an astoundingly bad practice. But everyone does it because it makes things a lot easier. Classic convenience vs safety tradeoff. None of us ever feels weâll be the one with a cell that goes into thermal runaway. 
Directing the ejecta sideways like that, if a cell goes into runaway, helps adjacent cells go into runaway. Fishpaper doesnât help much when the steel can gets burned through.
But mounting them directly against each other is bad practice too so how much extra does covering the vents impact safety? No way to quantify that. But covering the vents is a very, very bad practice.
Sure, a well designed pack probably wonât ever get even close to having a cell go into runawayâŚif the pack is never physically damaged badlyâŚif the electronics never short the packâŚif no connections ever short the packâŚif no cell has an internal defectâŚetc. But it can happen and the vents are there to try to keep the event from causing even more havoc.
We donât think weâll crash every time we get into a car but we still have air bags and seat beltsâŚ.just in case. The vents are there for the same reason and we cripple them for convenience when we cover them with nickel strip. Weâre adults though and are free to choose how to build our packs. IMO as long as we know about, and accept, the additional risk then we can build them any way we want.
What pack builders should tell their customers is an entirely different thing I am not diving into here. 
I agree and Iâm guilty of covering my vents too, Iâd sudgest cycling a pack before actually taking it for a spin to make sure things are OK tho.
I think the pack surviving vibrations are more worrysome then how its the cells are aligned in esk8 purposes.
Theoretically, a top mounted pack with cells standing tall could be made abit safer, but most of us cram cells into a confined space xD
Someone should really do an experiment to try to get a cell in thermal runaway, I gave my first pack hell abusing it, and only got dead cells, hitting it with a hammer, axe, throwing it around and I didnt even get smoke, either its been super used or 30q are really safe cells
Also its really hard to follow all the safety stuff when we just want POWER 
We could test hundreds of cells, in all kinds of situations, but that wouldnât mean that covering the vents is safe. For many cells itâs quite hard to force them into runway. But if it couldnât be done then there wouldnât be vents on all of them.
Many of us have used cells without incident for decades, abusing the hell out of them, but we canât apply any of that generally to say that something may or may not happen for someone else. Their cells and circumstances are completely different.
Iâll go back to the seat belt and air bag mention againâŚwe never think we will actually need them when we get into a car but because the consequences of a crash can be so great we have those safety features. Thatâs what vents do for us. They donât exist because we will definitely have a cell go into runaway. They are there to help keep that very, very low chance event from becoming much more serious.
Agreed! Another reason we trade off safety.
I use Teflon/PTFE wire for all the Onewheel batteries I make. Itâs a bit harder to strip, but I use a special wire stripper and it makes it easier.
In terms of durability, itâs the best Iâve used.
Silicone wires squish more easily, but I can strip them with my thumbnail easily.
PVC wire melts easily and deforms with heat, but I cannot strip or tear it without tool assistance.
PTFE is very strong.
Iâm not sure why thereâs such a veneration of silicone balance wires, apart from them squishing before actually crushing apart. But itâs the least abrasion/sharp resistant from my use and tests.
Hereâs a pack:
I think I did a decent job.
Hereâs another:
Hereâs a Onewheel pack I did with PTFE wire.
Historically (short history, but rife with numbers), wires being crossed without fish paper between them hasnât led to failures using PTFE wires, even when these kinds of packs are compressed heavily on installation.
Thatâs not to say one shouldnât consider doing that, but itâs worth having a realistic view of things.
Granted, itâs hard for me to have a realistic view of things myself since thereâs much I donât know and also have to balance anxieties with build completions.
Might be worth mentioning that our APEX packs are probably the closest thing there is to a âgoodâ pack right now.
All cells are mechanically isolated and air-gaped from the cells around them, both in series and parallel. This has cooling benifits as well as lowering the chance of propagation during thermal runaway.
The BMS is PCB mounted and has no balance wires to rub or short. Additionally if there was a short or failure at the BMS for whatever reason, all balance points are individually fused near the cells. As is the charge port.
The only concern currently for us is the vent situation but this is something we are aware of and hope to address in the near future.
Wouldnât the trampa packs fall into that category as well?
Iâm theory yes.
However with their current design the balance PCB spans the entire top and bottom of the pack. I canât see any way they could keep this style of construction whilst exposing the cell vents.
Plus their construction means you canât shrink wrap the battery or BMS. Plus they house this in an enclosure that is in no way waterproof.
Also The BMS circuitry is exposed inside the monster box and the charger can be plugged in backwards 
So in other words itâs perfect. Gotcha Iâll take 9
I tell them most of what youâve said. I advise them never to leave it charging unattended and to understand that there are inherent risks of using a very large battery. And that there are risks of having cells packed so tightly into an enclosure with little to no extra space for ventilation. We go over all the possible hazards and everything more than once and I usually show them how I mitigate risks, since I generally build for locals.
Every single one of them accepts all the risks with a smile and occasionally a raised eyebrow. They often have never been told to always supervise charging and not to charge a board overnight while they sleep.
I hammer that point in pretty heavy, and remind them that itâs one of the more dangerous moments for batteries, aside from riding.
I never soften the blow of the risks. Iâd rather them reconsider and get an ebike or something, than get a custom board or build a DIY with any misconceptions that were caused by me.
Oh boy⌠this will produce some popcorn worthy replyâŚ
I doubt he will reply honestly
Also, Iâve opened a few EUC batteries.
The stuff youâre worried about here is laughed at inside those.
Lol surely that is worse with their single point of failure, no?
Cells glued together with a smear of thermal glue. No isolation anywhere, right on a PCB with integrated BMS that doesnât do much at all. Like, allowed charging beyond 4.3v when one P group was dead and total voltage was low. Just not the most confidence inspiring stuff.
Made me feel way better.
Oh, and a series connection that was a single 0.2x8mm nickel strip.
I would be scared to ride anything with that level of quality in it
Granted sure, they have less vibrations, but stillâŚ
Yeah we sure see a lot of untested products in the PEV space
*Consumer tested.
Yes but China.
Having seen inside a few ebike batteryâs myself I can confidently say I will never own a cheep ebike.
