Six cells from three sources for these 
but that still means absolutely nothing for a different batch of them. Or even cells from the same company and batches.
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Ah okay well same point stands
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Ok sorry. I guess it would be fair to say if you tested 100 of them? And built a pack to see the performance over some time?
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I dont think the problem is the number of cells tested. The problem is the uncertainty behind where these cells are sourced, how they were stored, whether they were used, the batch they came from, how old they are, their grade, etc. etc. etc. There are too many unknowns for anyone to guarantee anything about these cells.
With the big name brand suppliers it’s more reasonable to expect a certain level of consistency between cells and batches, but even then there is variation.
These “Tesla cells” are essentially re-wraps of unknown (or at least un-verified) origin. You could test 1000 cells but that does not guarantee that the next 1000 will be good, or even the same cell. We just dont know, and so any decisions to use them have to be taken with the knowledge and awareness of risk.
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No, we cannot say that.
No amount of testing will tell you how other salvaged cells from different cars, with top contacts added on, will perform or what risks you might, or might not, be taking using them.
You want me to say that the odds are fairly good that any of these salvaged cells that we might buy will be okay? Sure, there is a good chance they all will be.
But that is no guarantee…none. So we cannot say that I verify anything. We cannot say that these cells will be relatively safe or perform well for anyone because we have absolutely no idea what the condition is for any cell that hasn’t been tested. Even then there can be issues that appear later. A few discharges for a cell guarantees nothing.
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If they were doing something shady, you probably would have noticed. You for 6 very random samples and all tested well. They probably were all stored together
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Sure, I agree.
But there is a huge difference between what we think is probably the situation and stating that I verify that all of these cells will perform the same and be safe.
Think of it this way…
Would anyone test six of these cells and then offer $10,000 to anyone who got a cell that didn’t perform the same or that they had safety issues with?
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would anyone even do that for brand new brand name samsung cells?
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My renters insurance is the one taking this risk for me haha
I can “bet” up to $25k
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I would, in a flash, for any established cell from a major manufacturer. As long as I got them from the manufacturer or a trusted source.
The field failure rate for cells from the large manufacturers is most often quoted at one in a million, or a lot lower. We can’t even begin to estimate field failure rates for cells being used after being salvaged.
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Here’s my testing contribution so far, I’ll be our ‘road tests with logging’ guinea pig.
12s11p w/ Tesla 2170 cells.
Only about 225km into this pack, BMS is getting an upgrade so I’ll be able to monitor individual Pgroup voltage soon.
Log:
2021-04-05T033429.csv (1.4 MB)
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I’ve been riding a 12s5p pack I made with them as well, noticeably less punch with them than 30Qs, but the range is insane. Lack of punch could be from serial connections just being 2 layers of 2mm folded nickle–does that make a difference?
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Your settings will determine that. If you lowered them because you know the limits of your pack then that’s normal. If it’s slower with the same settings then you need to lower them.
Here’s what it was: I ran a 12s4p 30Q’s with dual TBVESC4.12 (Them oldschool fuckers), with 40A battery and 50A/motor, and now running the 12s5p tesla cells with a unity at 75A battery and 50A/motor. I know that doesn’t make sense to have the battery amps that higher for tesla cells vs. 30Qs, but I wasn’t getting shit for punch with the teslas so I cranked it up, and it didn’t really seem to make a difference.
edit:
a unity at 75A battery and 100A/motor.
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Is this 100A per motor? Or total? I can never remember if Unity/Stormcore values are divided or shared.
Either way, “Motor Amps” are the maximum power that will be seen by your motor at any duty cycle. That means there is absolutely no benefit to setting your battery amps higher than your motor amps. The VESC will never drive your motors with more amps than what you have your motor amps set to.
The inverse is not true, you can set your motor amps much higher than your battery amps, and at low duty cycles you will get that amount of current to the motors, which tapers off as you near full duty cycle, and are then limited by the battery amps.
I would reccomend bumping up your motor amps considerably until you get the “punch” you are looking for. Your low end “punch” can be increased a lot by bumping up the motor amps, your top end “punch” will be limited by your battery amps or motor amps, whichever is lower.
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It’s so nice to have both high and low punch, make all this diy bullshit worth it
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In that case, the tesla cell is probably not the one you are looking for haha.
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Oh I know, unless you have a lot of them
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I’m not sure either, been wondering this myself too 
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