I haven't, although I did do linear regressions for each of the lines here: 3.0 Battery Longevity and then a two-variable linear regression here 3.0 Battery Longevity. I should try the exponential, too.
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I haven't, although I did do linear regressions for each of the lines here: 3.0 Battery Longevity and then a two-variable linear regression here 3.0 Battery Longevity. I should try the exponential, too.
Kerios
Member
Those comments about the Model S made me wonder whether there are similar date sets available for the S, particulary for those with batteries we think have similar chemistries to the 3.0 Roadster pack, additionally is there any data where packs have been replaced and subsequently had the performance/degradation mapped?
If we could point to similar cells showing either a trend, or difference it might help our argument collectively if/when those with 3.0 packs need to make it...
If we could point to similar cells showing either a trend, or difference it might help our argument collectively if/when those with 3.0 packs need to make it...
JRP3
Hyperactive Member
I don't think the Roadster cells are similar to any S cells.
...nor any other cells that anyone could find (if I recall the earlier discussion) being used in an automotive application. So, we're on our own here.
That would be ok, if a) we knew it going in, and b) Tesla would engage with us to collect data on cell performance, etc. as part of a 2-way research project. 2-way in that we would be getting some benefit from that research down the line in the form of a yet better battery pack. Though, I think $29k is kind of steep to be charging a research subject.
Perhaps I'm overstating the experimental nature of putting the cells into this application. After all, that's what the original car was, too. But given the data we're collecting, and the implications of it, I would certainly prefer to have a bit more engagement by Tesla in the matter. If the trend is primarily driven by time, and if it continues along the current slope, these cells won't last half as long as the original ones.
JRP3
Hyperactive Member
I thought they were found to be quite similar if not the same as a NMC LG cell.
Yeah, that sounds about right. So the cells are known and available, but when asked if anyone had used them in an automotive application, nobody could name one. That's what has me concerned, since the application can have significant impact on cell life.
Countering that, if we are seeing calendar time being the major factor, the application probably isn't a factor, which is inconsistent with Tesla choosing them for this use. So, the more I think about this, the more confused I get.
JRP3
Hyperactive Member
Unless the capacity loss starts leveling off soon this is all very odd to say the least. Did some digging and found some old links:
Roadster 3.0
LG HG2 18650 3000mAh 20A Battery
INR = NMC
Roadster 3.0
LG HG2 18650 3000mAh 20A Battery
INR = NMC
Mark77a
Member
I'm Bi-curious about the 3.0 battery - but if I had one I'd be tempted to buys some of these cells and fast cycle them on a rig to rapid lifetest - often the only way to get a full picture: (or put them to good use > F5B vertical climbs in silence - too fast to video
)Updating with a couple of weeks' data for #33 (he did a long drive and had a step drop in his CAC) and mine (I ranged charged once and had a small gain). Also adding #2, which is an extreme case of low mileage. It hasn't been driven even a tenth of a mile since July, and has 109 miles in 414 days since upgrading an essentially new original battery (CAC 156.4). It looks like a real outlier on the days graph, but it seems like the CAC algorithm doesn't run unless you drive the car some, which isn't happening. The CAC hasn't changed at all to seven digits precision since 12/8/2016 at 56.8 miles on the new battery. So, I'm not sure we learn much except that not driving means not updating the value. My guess is if it went out and drove a few hundred miles that we'd see a gigantic step drop in CAC to ~200.
Just for reference, here's the latest update date, days on 3.0 battery and miles on 3.0 battery for each car:
# Date Miles Days
670 1/20/18 25,461 463
181 1/5/2018 16,241 512
33 1/18/2018 6,256 522
425 10/11/17 7,308 460
537 7/12/2017 4,407 455
660 10/20/17 2,422 335
330EU 10/2/17 1,268 102
277 9/30/17 4,679 125
255 11/30/17 2,626 134
707 9/24/17 406 125
209 11/3/17 3,273 223
541EU 11/4/17 1,528 240
2 1/13/18 109 414
[I formatted this nicely as a table, but the forum software is taking out the multiple spaces and making it look bad. I'm sure there's a better way to do this, but I don't know how. Mods: if you feel like fixing this, be my guest.]
# Date Miles Days
670 1/20/18 25,461 463
181 1/5/2018 16,241 512
33 1/18/2018 6,256 522
425 10/11/17 7,308 460
537 7/12/2017 4,407 455
660 10/20/17 2,422 335
330EU 10/2/17 1,268 102
277 9/30/17 4,679 125
255 11/30/17 2,626 134
707 9/24/17 406 125
209 11/3/17 3,273 223
541EU 11/4/17 1,528 240
2 1/13/18 109 414
[I formatted this nicely as a table, but the forum software is taking out the multiple spaces and making it look bad. I'm sure there's a better way to do this, but I don't know how. Mods: if you feel like fixing this, be my guest.]
supersnoop
Tesla Roadster #334
A friend brought this thread over in the Model S section to my attention: Early 75/75D pack degradation
It seems @wk057 has found evidence of accelerated battery degradation in some of the 75 and 90 kWh packs. Is there any likelihood of a link to what we are seeing on the 3.0?
It seems @wk057 has found evidence of accelerated battery degradation in some of the 75 and 90 kWh packs. Is there any likelihood of a link to what we are seeing on the 3.0?
Marius
Member
David,
You have a remarkable pack, it is already more than 7 months old and only 3 CAC points down. Do you know what they fiddled around with your electronics at the beginning because first you started with CAC 205 and then it was altered to the promised 215 and now it does not decline.
All the others decline more rapidly
You have a remarkable pack, it is already more than 7 months old and only 3 CAC points down. Do you know what they fiddled around with your electronics at the beginning because first you started with CAC 205 and then it was altered to the promised 215 and now it does not decline.
All the others decline more rapidly
After range charging yesterday, I got this. I fear I may have seen the last of the 300 mile ranges.
In terms of real-world range, who knows? I haven't driven it to empty, and that depends so much on conditions, route, driving style, etc. that it's hard to measure. My informal observation is that it behaves pretty much like it always has, getting somewhat less than one real mile per ideal mile unless you're painfully careful. That is, it's not acting substantially better or worse than ever, and as far as I can tell the ideal range is still an accurate estimate of the useful energy in the battery.
I don't think there were any electronics changed, from the log files it looks like the same firmware was reinstalled.
Marius
Member
So, it could be a nice option to have Bolosky ask the SC to reinstall his firmware as well and see if this gives him back some CAC points?
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