Tesla Model S battery degradation data • Hacker News Board

Re: Tesla Model S battery degradation data

#41

Post by epistasis » Thu, Aug 31, 2017, 10:36 PM UTC

dmitrygr wrote: post #21

epistasis wrote: post #14

Earlier quoted context omitted.

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?

I provided a citation. Feel free to google around to find more info. This is basically how everyone models LiPo and Li-Ion cells. Tesla only publishes marketingspeak (which makes sense - that makes them money). Look for actual science and you'll see

Weird, was that there when I replied? I definitely don't remember seeing it there... Perhaps I was just rushed.

In any case thanks for the source!

Re: Tesla Model S battery degradation data

#42

Post by TomMarius » Thu, Aug 31, 2017, 10:38 PM UTC

sorenjan wrote: post #33

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've never seen anyone put more than one kilo before the unit before.

For me, it's normal to write "its mileage is 165k" - and the "km" is assumed. I just wanted our friends that use imperial units to understand, you're true it's non-standard, and it's actually the first time I wrote it like that.

Re: Tesla Model S battery degradation data

#43

Post by [deleted] » Thu, Aug 31, 2017, 10:39 PM UTC

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?

[deleted]

Re: Tesla Model S battery degradation data

#44

Post by dmitrygr » Thu, Aug 31, 2017, 10:39 PM UTC

vvanders wrote: post #36

dmitrygr wrote: post #17

Earlier quoted context omitted.

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

Sure, but you lead with: > not because of amount of use, but because of time Which makes it seem like time is more important that heat.

heat != use

think of it more as

BADNESS = integral(abs(temp - 5), over time) * integral(abs(charge_amt - 40%), over time)

Re: Tesla Model S battery degradation data

#45

Post by dmitrygr » Thu, Aug 31, 2017, 10:41 PM UTC

sqeaky wrote: post #35

dmitrygr wrote: post #30

Earlier quoted context omitted.

They are rated in cycles so consumers do not need a degree in physics to understand the reality. Feel free to inspect a REAL spec sheet for a LiPo battery from a manufacturer (I think ATL provides some online)

Can you provide links? You clearly feel we have never seen a "real" sheet, perhaps more hand holding is order. I would appreciate the experience and would not do it without the link.

I am trying to find some non-NDA specs online for you. I saw this when I was working with these for a job and the specsheet was NDA (and I no longer work at the place this was)

Re: Tesla Model S battery degradation data

#46

Post by dom0 » Thu, Aug 31, 2017, 10:44 PM UTC

JshWright wrote: post #16

epistasis wrote: post #14

Earlier quoted context omitted.

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)

> human-centric temperature scale

One point (100 °F ~ 37 °C) doesn't make a scale.

Re: Tesla Model S battery degradation data

#47

Post by Zekio » Thu, Aug 31, 2017, 10:44 PM UTC

mschuster91 wrote: post #18

RachelF wrote: post #11

Earlier quoted context omitted.

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 sp…

Pretty sure all newer thinkpads can be configured to only charge to a threshold

Re: Tesla Model S battery degradation data

#48

Post by nathancahill » Thu, Aug 31, 2017, 10:45 PM UTC

sqeaky wrote: post #40

seszett wrote: post #22

Earlier quoted context omitted.

165 000 miles is 266 000 km, for the readers who might wonder. My car is at 350 000 km now, and I'm not planning on selling it anytime soon. It doesn't have any special problem, except for a malfunctioning electric window lifter on one side. It's only one data point of course.

What percentage of car owners do this? There is some percentage of cars crashed in the first week. It only takes a few of these to cancel out the average of extreme outliers like your car. For reference I have never seen an odometer with more than 200 000 on it before. Even most classic rebuilds I have seen like 69 Corvettes have some high 100K count on them, some event have reset odometers.

Huh, I drive a Toyota with 205,000 miles on it. Still in great condition after tons of cross-country road trips.

Re: Tesla Model S battery degradation data

#49

Post by Animats » Thu, Aug 31, 2017, 10:46 PM UTC

sqeaky wrote: post #40

seszett wrote: post #22

Earlier quoted context omitted.

165 000 miles is 266 000 km, for the readers who might wonder. My car is at 350 000 km now, and I'm not planning on selling it anytime soon. It doesn't have any special problem, except for a malfunctioning electric window lifter on one side. It's only one data point of course.

What percentage of car owners do this? There is some percentage of cars crashed in the first week. It only takes a few of these to cancel out the average of extreme outliers like your car. For reference I have never seen an odometer with more than 200 000 on it before. Even most classic rebuilds I have seen like 69 Corvettes have some high 100K count on them, some event have reset odometers.

I'm up to 235,000 miles on a 1985 Ford Bronco as the original owner, but that's a 2-ton truck. High-mileage trucks aren't that unusual.

Re: Tesla Model S battery degradation data

#50

Post by tinus_hn » Thu, Aug 31, 2017, 10:47 PM UTC

obblekk wrote: post #5

Is there a non-linear decline at the end? i.e. do the batteries at some point just give up and capacity starts declining very quickly?

In the comments it is explained that this is because there is only one user who made it that far so the graph is skewed towards that users data. That users battery happened to be slightly worse than the mean so the graph goes down. It doesn't really mean anything.