Good call!
If this cell performs poorly or self-discharges quickly then perhaps the seal was breached and the electrolyte has started evaporating.
@Venom121212, is there a distinctly chemical smell coming from the top of that cell. Like a sickly-sweet solvent?
No smell but cell #2 has another similar defect.
Also, the second white insulator ring is off white and more rubbery like an O ring.
I jump this pack and offroad a lot with it. I wonder how much damage that could cause. It was suspended in foam but definitely felt some vibrations.
Iâve never seen damage like that on a cell so perhaps it is from welding, as @TheBoardGarage posted. Itâs way off to the side thoughâŚ.weird.
The manufacturers say to protect cells from shock and vibration but I havenât seen any data on how much they can actually handle before being damaged internally. The frequency of the vibrations could be as important as their strength.
Always good info! Is there a recommended way to measure IR of the cells or p groups? We have access to a D6 pro and I want to rule out human error.
If the D6 Pro has a that feature then definitely use it. 
It would measure the resistance of the cell but also all the wiring and connections too. Itâs important to reduce that extra resistance and to have a very, very good connection to the cell.
If the D6 Pro doesnât measure IR then you either need a dedicated IR meter or a charger that has that feature. But I have never seen a round cell charger that has anything but terrible accuracy. Perhaps the LiPo chargers do better.
I use the ESR Meter from ProgressiveRC but itâs an expensive device.
Measure the IR of a known good cell before testing any others of the same model number. This will give you a baseline to compare to. Otherwise you donât know if a high reading is due to inaccuracy, wiring/connection resistances, or is just from the cell.
Always measure at about the same cell temp and state-of-charge. I typically measure fully charged cells that have sat for one hour after charging is done so they can come back to room temp. Warm cells have a lower IR.
Actually while on the topic, I know the answer is probably âdepends on your risk toleranceâ but what do you think about these?
I mean theyâre dented a little bit, personally Iâd feel fine using them for myself
Too bad fogstar wasnât US lol
UmmâŚyup. 
Thereâs no way for anyone to know whatâs going on inside any cell with damage, which is why no damage is acceptable to the manufacturers. We just canât say when it becomes a safety issueâŚtoo many variables and unknowns.
Itâs up to each of us to decide what looks okay and what looks too risky to use.
100% No-Go for me would be smoke and/or fire. 
About the degree of damage for that left cell is where I would start feeling uncomfortable. But that should never be used as any metric for your decision. I canât know anything about the internal condition of any dented cells I have and any decision I make is merely a wild guess. It canât be any more reliable than that.
The cell on the right I would use as long as I knew it wasnât banged around a lot, just dented from testing.
Any further details you can share on this?
Any further info on the problem?
Anything people of the forum can do to check this wonât affect their packs?
Any details on what software changes are being made?
Are you rewrapping or double wrapping your cells?
Rewrapping. Theyâre salvaged from BCH. Some of the wraps were torn and didnt want two colors. OCD much lol
Does anyone know a compact 20s BMS that does balancing?
I only find gigantic discharge bms or small bms that donât balance.
I only need like 20-30A discharge
This but Iâm looking for charge only for a onewheel
Yes mine is also for a OneWheel. Ideally i would like to use the switch of the bms for the OW. An additional 20s Anti spark probably wouldnât fit.
Iâm probably going to use this one but itâs a very tight fit.
Also. I have 27 of the 4p 18650 tabs from @BenjaminF left over. They need a good home. Take care of shipping and their yours.
