Seems the forum doesn't want me to unsubscribe to this thread. It keeps popping back up in my list, so, guess I'll try later.
No, just done having to defend my data and conclusions against people with no credibility. Private discussions elsewhere are much more appealing and useful at this point. My absence in this thread is in no way "tapping out" since that would imply that I somehow have lost the battle, which I clearly have not. It's a fight not worth fighting. Again, the data speaks for itself. I've logs from over 20 cars, from brand new to a signature VIN S00XXX. Not a single one shows pack capacity at or even close to 85 kWh as reported by the car itself. Data which matches my own testing of cells outside the car, and the tests of others.
I don't care what Tesla does with the cells prior to delivering them to customers, or not. If the product I received doesn't meet spec, then it doesn't meet spec. Plain and simple. People are welcome to verify this for themselves, and I invite them to do so. I've outlined the relevant BMS CAN messages here.
Maybe next time you should keep your "conclusions" to yourself given their implications....
First, let's actually quote things with context.
It might not sound like a big deal, but it kind of is. Today, Tesla has a 90 kWh pack upgrade (which is likely not actually 90 kWh either, but unconfirmed) that costs $3000 for an additional 5 kWh. Well, the "85" pack is missing 4 kWh to begin with, so extrapolating that out everyone with an 85 pack overpaid by about $2,400. As the buyer of a total of three 85 version Model S, that's $7,200 worth of capacity that I never received. That's significant.
This was obviously my attempt to show that the capacity difference was significant, using a monetary value derived from Tesla's own pricing, for folks who may or may not have understood the delta.
I could care less about the implications of what the data tells. The data says that customers never received a pack that Tesla labeled "85 kWh" that could actually be charged to 85 kWh in or out of the vehicle. That's a fact based on mountains of data, including admission of the cars themselves.
If the data said that the pack was say an 86 kWh pack (it does not) we wouldn't be having this conversation, and people would be praising Tesla for under promising on the spec and everyone would be happy. Instead it's data that shows that the spec doesn't match the advertised spec, however little the delta, and for whatever reason that triggers half of the forum to jump on the dog pile with the messenger at the bottom.
Personally, I'm just curious as to what the blog post that Tesla will eventually post in response to this issue, trying to explain it away like the P85D range issue and P85D horsepower issue, will read. The range issue blog I'm reasonably certain I personally triggered with my side by side testing of the P85 and P85D... either that or it was a complete coincidence that Tesla posted their blog post exactly as I was doing my pre-announced and publicized side by side testing.
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The cells are NCR18650BE, I said this a year ago...
Yes, you can get 11.9Wh out of a cell when new, even close to new.
They are rated at 3200 mAh.
I don't have a problem with Tesla's 85kWh rating
I don't know what Tesla cells you tested, but NCR18650B's are pretty poor performers. NCR18650BE will have much lower impedance because the B has a PTC, which increases resistance.
All modern cells no longer use a PTC.
500mA is too fast drain to measure Wh capacity. You need to use a quasi-static discharge... barring that... 50mA might be slow enough to get a proper Wh reading.
Also make sure you're charging to 4.2V with a 50mA charge cut. Kelvin connections are also a necessity.
Actual final post here, since I respect okashira on this, and if desired he's welcome to continue this discussion in private.
I'm not sure how you came to the conclusion that they're NCR18650BE. We can't both have the same cells, awesome test equipment, and come to drastically different conclusions. Some variable is different.
I'm well aware of how to test the cells. Actually, the latest iteration of the equipment being developed for this that I've been field testing for the company designing it includes complete thermal controls capable of holding the cell anywhere from -20C to 75C and capacity calculations accurate to a ridiculous +/- 5
mWh. It's literally accurate enough to measure degradation from cycle to cycle, and I
really wish I could share more information on the equipment because it's absolutely awesome. I know quite a bit about the cells and how to test them, and I had even made my own cycler for them prior to hooking up with the company I'm assisting. Using my lower end equipment I never got close to 11.9 Wh. I thought I did a few times, but it turned out to be an issue with the hardware (because the cells definitely don't hold 13+ Wh). Using the new equipment we've tried many different methods of charging and discharging the cell in an attempt to recover 11.9 Wh, or even close to it, and have not been able to. Thermal controlled, uncontrolled, constant current, constant power, varied power, varied current, etc etc etc. No dice on 11.9 Wh.
Fun that we have conflicting data, though. However, Tesla's BMS does in fact agree with mine pretty much exactly... so, not sure where that leaves us. Edit: Added data point being that I collect mountains of charge/discharge data from my ~16000 cells in my solar setup, and they also match nicely with my other data extrapolated out to the large scale full pack. I've not discharged my solar pack down to nothing, but I have charged it to 100% several time, and have discharged it on a few occasions below the voltage Tesla considers 0%... and the data still matches up with my single cell testing.