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Tesla Model S battery degradation data

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Re: Tesla Model S battery degradation data

#11

Post by RachelF »

mschuster91 wrote: post #2

What could explain the graphs and cycle stability is that Tesla does not deplete the battery pack below a certain percentage of the real battery capacity or over a threshold... basically they keep the battery pack well beyond the critical ranges where batteries degrade from simply idling, and they "undersell" the pack capacity.

I've always wondered how they do it.

They use the same 18650 cells that power laptops, yet laptop batteries degrade badly over time. My 1 year old XPS13 reports a battery "wear level" of 29%.

I wonder if Tesla's battery technology could be used in laptops and phones?

Re: Tesla Model S battery degradation data

#12

Post by colechristensen »

dmitrygr wrote: post #9

This is fundamentally flawed because lithium batteries mostly degrade not because of amount of use, but because of time (and their charge state and temperature during this time). No matter if used or not, they will lose capacity. The rate of capacity loss is mainly dependent of average charge (best is 40%, worst is 100%) and temperature (best is 5 degrees C, the higher the worse). (This is also why phone batteries fa…

Lithium batteries lose charge with use as well. Also rate of charge/discharge. It's more complicated than just one thing.

Re: Tesla Model S battery degradation data

#13

Post by vvanders »

sqeaky wrote: post #10
TomMarius wrote: post #7

Average life of ICE vehicles can't be 266kkm, that's absurdly low. Most of people I know have bought vehicles with that mileage and used it for another 100kkm after that at some point in their life (think first/second car, second family car, etc.). It's important to know that especially in Central/Eastern Europe, you can never trust the car's odometer - even the cars I'm talking about had probably more than 350kkm wh…

I have seen plenty of cars not make to 165_000 miles, those that do are often near the end of their life. Mine is beat and barely holding together and it is at 97_000 miles.

Yup, when I donated my car at 145k mi I expected to to be resold but got notified that it was turned into parts for $350(they had to report back to me for tax reasons).

Re: Tesla Model S battery degradation data

#14

Post by epistasis »

dmitrygr wrote: post #9

This is fundamentally flawed because lithium batteries mostly degrade not because of amount of use, but because of time (and their charge state and temperature during this time). No matter if used or not, they will lose capacity. The rate of capacity loss is mainly dependent of average charge (best is 40%, worst is 100%) and temperature (best is 5 degrees C, the higher the worse). (This is also why phone batteries fa…

Wow, I've never heard anybody say that before or model it that way before.

Though these tests are evidence of that, it's definitely not a common belief.

Before the Tesla data, what informed you?

Re: Tesla Model S battery degradation data

#15

Post by vvanders »

dmitrygr wrote: post #9

This is fundamentally flawed because lithium batteries mostly degrade not because of amount of use, but because of time (and their charge state and temperature during this time). No matter if used or not, they will lose capacity. The rate of capacity loss is mainly dependent of average charge (best is 40%, worst is 100%) and temperature (best is 5 degrees C, the higher the worse). (This is also why phone batteries fa…

Phone batteries do poorly because the SoC generates a ton of heat when used which gets dumped right on the battery pouch.

It's the same reason that you see early Leaf cells die out in Arizona while Tesla's have held up to 100k+. Thermal management makes or breaks longevity.

Re: Tesla Model S battery degradation data

#16

Post by JshWright »

epistasis wrote: post #14
dmitrygr wrote: post #9

This is fundamentally flawed because lithium batteries mostly degrade not because of amount of use, but because of time (and their charge state and temperature during this time). No matter if used or not, they will lose capacity. The rate of capacity loss is mainly dependent of average charge (best is 40%, worst is 100%) and temperature (best is 5 degrees C, the higher the worse). (This is also why phone batteries fa…

Wow, I've never heard anybody say that before or model it that way before. Though these tests are evidence of that, it's definitely not a common belief. Before the Tesla data, what informed you?

In the RC world, the '50/50' rule of thumb is common for lithium battery storage. 50% charge at 50˚F. It's close enough to the 'ideal' values, and easy to remember (for those of us used to a human-centric temperature scale)

Re: Tesla Model S battery degradation data

#17

Post by dmitrygr »

vvanders wrote: post #15
dmitrygr wrote: post #9

This is fundamentally flawed because lithium batteries mostly degrade not because of amount of use, but because of time (and their charge state and temperature during this time). No matter if used or not, they will lose capacity. The rate of capacity loss is mainly dependent of average charge (best is 40%, worst is 100%) and temperature (best is 5 degrees C, the higher the worse). (This is also why phone batteries fa…

Phone batteries do poorly because the SoC generates a ton of heat when used which gets dumped right on the battery pouch. It's the same reason that you see early Leaf cells die out in Arizona while Tesla's have held up to 100k+. Thermal management makes or breaks longevity.

yes... I said that...high temp is bad

Re: Tesla Model S battery degradation data

#18

Post by mschuster91 »

RachelF wrote: post #11
mschuster91 wrote: post #2

What could explain the graphs and cycle stability is that Tesla does not deplete the battery pack below a certain percentage of the real battery capacity or over a threshold... basically they keep the battery pack well beyond the critical ranges where batteries degrade from simply idling, and they "undersell" the pack capacity.

I've always wondered how they do it. They use the same 18650 cells that power laptops, yet laptop batteries degrade badly over time. My 1 year old XPS13 reports a battery "wear level" of 29%. I wonder if Tesla's battery technology could be used in laptops and phones?

You can replicate it to a certain extent by not discharging below 10-20% (don't know the exact range though). Limiting upper bound is likely either impossible or requires reprogramming the battery control unit.

What is also an advantage: Teslas can cool (and I believe also heat) the batteries so they don't enter temperature ranges where degradation is accelerated. In a laptop and certainly a phone there is neither space nor weight available for a thermal management.

Re: Tesla Model S battery degradation data

#19

Post by r00fus »

mschuster91 wrote: post #2

What could explain the graphs and cycle stability is that Tesla does not deplete the battery pack below a certain percentage of the real battery capacity or over a threshold... basically they keep the battery pack well beyond the critical ranges where batteries degrade from simply idling, and they "undersell" the pack capacity.

The Prius did this - fanatically keep it's NiMH battery at between 20 and 80% charge.

I'm pretty sure cell phones do this too.

Re: Tesla Model S battery degradation data

#20

Post by dom0 »

sqeaky wrote: post #10
TomMarius wrote: post #7

Average life of ICE vehicles can't be 266kkm, that's absurdly low. Most of people I know have bought vehicles with that mileage and used it for another 100kkm after that at some point in their life (think first/second car, second family car, etc.). It's important to know that especially in Central/Eastern Europe, you can never trust the car's odometer - even the cars I'm talking about had probably more than 350kkm wh…

I have seen plenty of cars not make to 165_000 miles, those that do are often near the end of their life. Mine is beat and barely holding together and it is at 97_000 miles.

97 000 miles, just barely 160k kilometers. That's... really not much at all.
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