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Wiki Sudden Loss Of Range With 2019.16.x Software
- Thread starter Dutchmeeuw
- Start date
BigNick
Infamous Fat Sweaty Guy
There is also this, showing they knew limiting max voltage to 4.15V instead of 4.2V would reduce stress on the cells, and that was implemented in the Roadster: A Bit About Batteries
DJRas
Member
The datasheet specifies a fast charge, which is 4000 mA constant current, then 4.2 V constant voltage, then cut off at 100 mA, which is a C/25 charge termination.
Thanks, that made me stumble across this, Tesla Roadster (first generation) - Wikipedia
"The pack is designed to prevent catastrophic cell failures from propagating to adjacent cells (thermal runaway), even when the cooling system is off.[121] Coolant is pumped continuously through the ESS both when the car is running and when the car is turned off if the pack retains more than a 90% charge."
Just like my S60. Maybe I got old Roadster cells in the battery swap last year. I even have nominal capacity of 54 kwh now
DJRas
Member
DJRas
Member
From 2015
Charging Lithium Ion Batteries
The lithium battery charging algorithm consists of constant current and constant voltage stages. Here are a few ideas on how to charge you lithium batteries.
www.digikey.com
C rate explained here
What Is A Battery C Rating & How Do I Calculate C Rate - Power Sonic
Power Sonic look at what a battery C Rating is and how that C Rate is calculated. Includes battery C Rate charts, formulas and examples.
www.power-sonic.com
More to the point is that Tesla doesn't use off-the-shelf Panasonic cells, so there is no datasheet available for the actual cells they use. (They are custom made for Tesla.)
I thought NCR18650B was close enough but ok. Regardless, 4 A turned out not to be safe so I'll bet they stretched the Panasonic spec.
DJRas
Member
Jason Hughes determined each cell in the 85kWh pack has 11.36Wh (thus the whole pack had 80.7kWh).
11.36Wh at 4.2volts is 2,704mah. But the nominal voltage for 18650 cells is 3.7 volts (usable 3.2 to 4.2 volts).
So, 11.36Wh / 3.7V = 3,070mah per cell. Clearly NOT std Panasonic 18650 cells.
Tear down of 85 kWh Tesla battery pack shows it could actually only be a 81 kWh pack [Updated]
Tesla Model S owner and battery tinkerer Jason Hughes published this week some of his findings following his tear down...
electrek.co
lightningltd
Member
DJRas
Actually my assumption was mostly based on this by Jason, 85-type | Battery Modules | Products | 057 Technology
where he writes "similar to NCR18650B". This however, Model S Battery Voltage?
seems to indicate the 60 and 85 cars have 'very similar to' NCR 18650A cells. Puzzling...
Actually my assumption was mostly based on this by Jason, 85-type | Battery Modules | Products | 057 Technology
where he writes "similar to NCR18650B". This however, Model S Battery Voltage?
seems to indicate the 60 and 85 cars have 'very similar to' NCR 18650A cells. Puzzling...
DJRas
Member
(Some randomness here, but don't feel like making a bunch of different posts)
The Model S 85 type cells are something completely custom. They're similar to NCR18650B in many regards, but not exactly. Tesla's definitely done something to the mix to make them capable of handling much higher than the listed NCR18650B charging rates... seemingly at the expense of some rated capacity. The other tradeoff seems to be that extended use of this higher charge rate capability would cause the "surface charge" capability of the cells to deteriorate over time, resulting in a faster ramp up in IR than new cells, or cells that didn't supercharge, when under initial load/charge as the cell degrades.
Interestingly, this change doesn't seem to negatively impact capacity loss substantially, just impacts the ability to efficiently use that capacity due to the IR increase. I've got well over 1.5 million miles worth of simulated supercharge trips on a few 85 pack type test cells I've had running for around 7 years now, and they're still going strong with > 65% capacity retention. In fact, continued capacity loss is almost non-existent and holding level. I expected them to completely fail at some point, but they haven't. However, judging by the IR profiles of these, if they were driven harder than my original simulation (which emulates some real highway trips I've taken over and over from before superchargers were as plentiful and I was driving efficiently) I think the performance drop would be quite noticeable... possibly even unusable for more than reasonable chill/efficient driving.
On the flip side, all of the gen1 90-type cells I've tested have all failed (capacity drop off a cliff to basically nothing). The first 100 type cells I had under test also appear to be close to failure (beginning of the cliff appears to have begun). The original release 90 type cells are absolute trash. Every single gen1 90 pack would have far less usable capacity today than an 85-type pack would with the same mileage.
I'm not a chemist, so I don't fully understand what changes they made and why they have the effects they do, but this is what I've seen in my own long term testing.
An important note: Unfortunately I don't own the equipment I've used for these ongoing tests. It was strictly licensed to me years ago where the company would have full rights to data produced by the equipment (exceptions being super high level data like noted above). They intended to showcase the data from the ultra accurate testing of cells from all over the world as part of their marketing push at release. However, the company that originally designed them is now bankrupt and never released the product publicly. I've not been able to purchase or otherwise acquire any rights to the equipment or data produced by the units as of yet... and I don't want to end up on the wrong side of their lawyers at the moment. I'm hoping that changes as this winds its way through bankruptcy court, as I'm attempting to buy the prototype equipment and release from the original contract/license as part of their financial settlements. Hopefully it works out, because I have a lot of interesting data about these cells...
The Model S 85 type cells are something completely custom. They're similar to NCR18650B in many regards, but not exactly. Tesla's definitely done something to the mix to make them capable of handling much higher than the listed NCR18650B charging rates... seemingly at the expense of some rated capacity. The other tradeoff seems to be that extended use of this higher charge rate capability would cause the "surface charge" capability of the cells to deteriorate over time, resulting in a faster ramp up in IR than new cells, or cells that didn't supercharge, when under initial load/charge as the cell degrades.
Interestingly, this change doesn't seem to negatively impact capacity loss substantially, just impacts the ability to efficiently use that capacity due to the IR increase. I've got well over 1.5 million miles worth of simulated supercharge trips on a few 85 pack type test cells I've had running for around 7 years now, and they're still going strong with > 65% capacity retention. In fact, continued capacity loss is almost non-existent and holding level. I expected them to completely fail at some point, but they haven't. However, judging by the IR profiles of these, if they were driven harder than my original simulation (which emulates some real highway trips I've taken over and over from before superchargers were as plentiful and I was driving efficiently) I think the performance drop would be quite noticeable... possibly even unusable for more than reasonable chill/efficient driving.
On the flip side, all of the gen1 90-type cells I've tested have all failed (capacity drop off a cliff to basically nothing). The first 100 type cells I had under test also appear to be close to failure (beginning of the cliff appears to have begun). The original release 90 type cells are absolute trash. Every single gen1 90 pack would have far less usable capacity today than an 85-type pack would with the same mileage.
I'm not a chemist, so I don't fully understand what changes they made and why they have the effects they do, but this is what I've seen in my own long term testing.
An important note: Unfortunately I don't own the equipment I've used for these ongoing tests. It was strictly licensed to me years ago where the company would have full rights to data produced by the equipment (exceptions being super high level data like noted above). They intended to showcase the data from the ultra accurate testing of cells from all over the world as part of their marketing push at release. However, the company that originally designed them is now bankrupt and never released the product publicly. I've not been able to purchase or otherwise acquire any rights to the equipment or data produced by the units as of yet... and I don't want to end up on the wrong side of their lawyers at the moment. I'm hoping that changes as this winds its way through bankruptcy court, as I'm attempting to buy the prototype equipment and release from the original contract/license as part of their financial settlements. Hopefully it works out, because I have a lot of interesting data about these cells...
Can you share how many simulated miles/charge cycles the 100 type cells have gone through to get to this point?
They have the same capacity as NCR18650A it seems. Are you sure they are not A-s? At least in the early models.
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