Just a question, but what adhesive is used to hold the fishpaper, busbars, and the whole pack together?
To hold cells together you can use hot glue or better electrical silicone. Fishpaper comes with adhesive.
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Well only if you buy the version that is adhesive backed, there is regular without adhesive but that is a pain in the but.
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I’m pretty sure I don’t want to get into this discussion about BMS and cell fusing together. 
If I was going to cell level fuse I would have the fused sized to only blow in a short circuit situation to prevent thermal runaway but not to prevent thermal runaway from heavy amp draw, that issue should be solved with good pack design and safe Vesc amp limits.
And cell fuses or not I would not trust a regular BMS to keep my pack in good condition. That’s just blind faith. 
I would only use a BMS if it monitored P group voltage sag or I was monitoring them with another method so I could see when one of the P groups lost capacity or was acting weird.
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I decided against cell level fusing after the above discussion. At the time based on my limited reading I considered it the gold standard of battery building. I weighed up the stated benefits of cell level fusing against the risks set out by @TowerCrisis and figured it wouldn’t make sense for my situation for the following reasons
- considerable extra effort to do cell level fusing
- planned build is 10s3p… the risk of a bad cell ruining an “entire” p group is not such a big deal if we’re only talking about 3 30qs
- my bms is from aliexpress and took over a month to be delivered, blowing it would be a total PITA
@TowerCrisis Cell level fusing is to prevent catastrophic damage from a resulting fire. Not to prevent damage to components.
Say your board has been run over by a car, cell fusing will help prevent a fire should the pack become damaged. Or lets say the box you shipped your board in becomes crushed, the cell fusing will help prevent catastrophe and possible loss of life.
I haven’t gone through this whole thread since I have been back but I don’t think it is a great idea to dissuade people from this method of construction if they have the desire to and means to do it. I know I sleep better at night knowing my packs are fused at the cell.
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Why not have multiple fail safes?
Literally thousands and thousands of people use a BMS to keep their packs in good shape, and for 99% of them it works. Why would you encourage people to NOT use a BMS?
This post really confuses me…
I was not saying to not use a bms, I just personally want to monitor the cells, either with a Bluetooth bms or some other additional method.
Your right they do work.
Might just be habit, paranoia, science or curiosity not sure.
I want to know if a p group is under performing ASAP, which is hard to tell with a regular bms until the p group is pretty far gone.
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Good, that’s not what I understood from your message above. Just wanted to be clear, didnt want a bunch or people running around sans-BMS and starting an Esk8 apocalypse 
.
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Lol 
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Are you saying that you pot your battery pack into the fiberglass enclosure for your deck or that you put the battery in it’s own fiberglass enclosure that is mounted to the board inside your enclosure for the rest of your electronics? Do you have any pics of this? Thanks
Wanted to chime in real quick and mention that barley paper is another alternative for insulation if anyone has a hard time finding fish paper in their neck of the woods.
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It’s funny. Never heard that name. I just googled It to find out i always had It.
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Why do automotive makers do it? I like the idea of isolating a rogue cell.
This would be much more your knowledge area I’m sure. Surely a rider would ‘know’ something is up from the time the power/current drops a bit?
The premise of destroying the rest of the pack due to a loss of 1 cell of the P, I dunno.
You would have to be pulling more amps continuously then that P could provide for some time to make it also go bad and then the fuses should start going on that too. I guess it depends on the current demand on the battery config
Well, it depends.
Plenty of electric cars and hybrids don’t even have significant P groups because they use very large prismatic cells (like 80 Ah each) so they don’t do cell level fusing.
Ones like Tesla baby their cells so much that I’d be surprised if a single cell ever fused out on their packs. I’m no expert on their batteries, but if we’re talking 50 cells in parallel, then one cell going out isn’t really bad. 49 cells vs 50 is only a 2% difference, which could be corrected by a BMS. In addition to that, Tesla’s cell level fusing is mostly for complete failiure, like a piece of rebar stabbing through the underside of the car. It will slow down the thermal runaway enough so that the passengers could get out of the car.
Keep in mind, their battery management is far superior to anything we use. It monitors P group performance, keeps track of which cells have likely gone bad, and has a multitude of safety features and a level of “self protection” that our BMS’s will likely never reach. They need this kind of ultra safe environment because they need a tremendously low failiure rate. Even 0.1% of these packs having issues would lead to a recall.
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Good thoughts thanks
This is interesting in esk8 application
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Hi guys ! Do i really need terminal insulator to build a battery pack? Thanks !
yes you do. they cost like £2 lol just get it
Well its just i dont have somewhere near by to get them… for 20700 cell…
Most I found are plastic, here’s some of the fish paper ones it seems- https://liionwholesale.com/products/20700-flat-top-battery-terminal-insulators-5pcs-blue?variant=8644889608286