Official Tesla Model S thread

[Valdemar]

Oh, I have no doubt the experiences are wonderful, it's the long term situation that worries me as in if Tesla is going to be around to honor my warranty claim. At any rate, barring unexpected circumstances I'm not in the market for a new car until 2-3 years from now, and it feels it is the next couple of years that will shape the next EV generation or the lack thereof and Tesla's future. My refurbed Leafy should be able to limp through, so it's all good.

[Evoforce]

Oh, I have no doubt the experiences are wonderful, it's the long term situation that worries me as in if Tesla is going to be around to honor my warranty claim. At any rate, barring unexpected circumstances I'm not in the market for a new car until 2-3 years from now, and it feels it is the next couple of years that will shape the next EV generation or the lack thereof and Tesla's future. My refurbed Leafy should be able to limp through, so it's all good.

I can understand. That why I currently do not own more than 1 Tesla because the Leaf is still capable of handling my wife's short commute to work. The second Leaf just sits there. Can't bear to sell it for next to nothing but have entertained making it part of my solar system and parting the rest out. It would really kill me to do that because it is in excellent condition.

[DaveEV]

The point being without knowing how Tesla BMS works, and no one except Tesla engineers does, it is impossible to know how much capacity is actually lost in absolute terms. Range loss is not necessarily 1:1 to capacity loss, until the battery ages to a certain point anyway.

From wk057 via TMC:
https://teslamotorsclub.com/tmc/threads ... st-3587938

tl;dr;
There are people (like wk057) who have analyzed how the Tesla BMS works, as well as analyzed individual cells. Tesla isn't hiding anything, except for a few kWh at the bottom to help ensure that people don't get stranded and that they can drive to at least 0 miles remaining.

Tesla has changed the balancing algorithm many many times over the years. Originally this was a very dumb setup that would only kick in once a cell group reached a threshold voltage, usually around 90-93% SoC. This is no longer the case.

First, let me point out that Tesla's BMS software has come a LONG way... I'd consider it a work of art now. Lots of genius in there. It's absolutely amazing and full kudos where kudos are due here.

One thing they're now able to do is to calculate out the capacity of individual bricks of cells (96 in the 85/90/100, 84 in the rest) based on a ton of factors and compute this in near real time, in a full range of conditions, with almost magical accuracy. They're basically running physics simulations (similar to how they calculate out unmeasurable metrics in the inverter firmware, like rotor temperature) of the entire pack based on measured power usage/charge, balancer usage, temperature, temperature delta based on coolant flow and coolant temp, predicting temperature gradients, and probably 100 more variables. This is the holy grail of proper balancing for safety and longevity for a battery pack. This is not a dumb system anymore by any means. Knowing the actual capacity of the individual bricks allows them to know exactly which ones need cell bleeders enabled, and for exactly how long. With this data, they can balance on the fly at any SoC, and just use top and bottom SoC windows for fine tuning, validation, and calibration.

The car balances all the time whenever its needed. It knows when a cell group will need balancing before it's even out of balance... which is really freaking weird when you think about it, especially if you're watching a playback of the pack balancing and voltages and see it engage a balancer on a cell group that doesn't look out of balance at all, and watch it fall completely in line still at the end of a charge or discharge cycle. It keeps track of which groups will need it, which wont, how long they'll need it, how much they've been balanced, etc.

It really is an epic setup now.

The short answer to the balancing question: It balances any time it needs to balance.

As for SoC shenanigans, yes getting closer to 100% or 0% will give it a chance to tune things better... but it's not needed anymore. Just charge like you need to, and drive.

[DaveEV]

The Longest-Range Electric Vehicle Now Goes Even Farther
370 miles of range thanks to squeezing more efficiency out of the vehicle (same battery 100 kWh battery pack as before). Biggest change is that they are using the Model 3 rear motor up front in the S/X now, have updated lower rolling resistance wheel bearings and tires. Model S/X will now charge at up to 200 kW on Supercharger V3.

MotorTrend drove one from Fremont to Hawthorne (365 miles) and still had an indicated 40 miles remaining.

EXCLUSIVE: CAN A 2019 TESLA MODEL S MAKE IT FROM SF TO LA ON ONE CHARGE?

As we pull into the Supercharger stall, our elapsed time from the Bay Area stood at 6 hours, 11 minutes, 359 miles. With 83 kWh used, we had 11 percent of the battery remaining—which equates to 41 more miles at the rate I was going. Right at 400 miles if you add it up.

[Valdemar]

Thanks, I guess that's as much of a proof one can get.

[EVDRIVER]

How can you see your pack true capacity? There is always an inaccessible portion of the battery capacity called a buffer, oversized initially. Capacity losses shrink the buffer first, then when the excess of the buffer is gone capacity losses must come from the user-accessible part of capacity that directly translates to reduced range. I always thought it was EV 101.

A 2014 P85 has about a nominal capacity of 80-81kWh. Here are some real numbers from cars today and about average for most. Please don't spread FUD or make assumptions. There is no capacity adjustment over time.

94K miles 72kWh
125K miles 72Kwh
88K miles 73kwh

So, very low degradation in general for the miles and all about 5 plus years old. Not to mention these cars have moderate to high SC use.

[dgpcolorado]

While the larger battery cars appear to have moderate degradation, according to numerous user reports I've seen, some of the S60s, such as mine, have quite significant loss of capacity. I'm down 15% at 69,000 miles in a five year old car (176 Rated Miles* at 100% SOC). Some S60s are worse off but I know of one of the same vintage that has triple the mileage and significantly better capacity — go figure.

I presume that the S60s show more degradation than the S85s (or S75s, S90s, S100s) because the small battery gets worked much harder. In my case the capacity loss may also be due to extensive use of Supercharging, since most of my miles are from long road trips, although that is just a guess. My plan is to put a new battery in my car in a couple of years, when the range gets to the point that it becomes too difficult to make long trip legs at highway speeds. For local driving the capacity loss is completely irrelevant.


* Unlike the LEAF GOM miles number, which varies with driving conditions, the Tesla Rated Miles is actually a battery capacity measure: it is the SOC (Wh) divided by the EPA efficiency (Wh/mile) = RM. In effect, the RM number is a finely divided fuel gauge, not an estimate of how far one can go (unless one drives at exactly the EPA efficiency number).

[SageBrush]

* Unlike the LEAF GOM miles number, which varies with driving conditions, the Tesla Rated Miles is actually a battery capacity measure: it is the SOC (Wh) divided by the EPA efficiency (Wh/mile) = RM. In effect, the RM number is a finely divided fuel gauge, not an estimate of how far one can go (unless one drives at exactly the EPA efficiency number).

Bjorn Nyland just did a range test of his Model X 90D battery at 100k miles. At 100% SoC the car reported 223 miles of range. EPA averaged city/highway is 36 kWh per 100 miles which implies 80 kWh capacity but his range test resulted in ~ 71 kWh. Bjorn thinks the discrepancy is due to increased battery resistance. Whatever the reason(s) may be, it suggests that the RM may be optimistic over time.

[WetEV]

I'm down 15% at 69,000 miles in a five year old car

According to LeafSpy today I'm down 12% in 5 years and 50k miles. Your S60 has 3 times the battery size of my car.

[GRA]

I'm down 15% at 69,000 miles in a five year old car

According to LeafSpy today I'm down 12% in 5 years and 50k miles. Your S60 has 3 times the battery size of my car.

You live in flat, cool Seattle and he lives in mountainous western Colorado, and I expect you have totally different use cases and L2/QC % as well. A related article on Bjorn Nyland's X P90DL, via IEVS:

Tesla Model X P90DL Battery Degradation After 62,000 Miles: Video

https://insideevs.com/news/346847/video ... gradation/

8% of battery capacity/range gone after 100,000 km (62,000 miles), but that's because of the trailer

In his last test of the Tesla Model X P90DL Optimus Prime before the sale and switch to a Model 3, Bjørn Nyland tested the battery degradation.

After around 100,000 km (62,000 miles) of the second battery pack (the first was replaced after 116,000 km (72,000 miles) under warranty, the overall capacity fade seems to be at around 8%.

Second battery pack 81.9 kWh (new):

35,000 km (21,800 miles): 79.3 kWh (down 3%)
75,000 km (46,600 miles): 77.2 kWh (down 6%) - 368 km (229 miles) of range assuming 210 Wh/km
100,000 km (62,000 miles): 75.1 kWh (down 8%) - 349 km (217 miles) of range assuming 210 Wh/km

I'd expect degradation as good or better than Seattle's in say Oslo, and Bjorn's putting miles on at a higher rate than either of you, so calendar degradation is less of a factor.