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Tesla Model S battery degradation data

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Re: Tesla Model S battery degradation data

#81

Post by thinkling »

IkmoIkmo wrote: post #25
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…

> Average life of ICE vehicles can't be 266kkm, that's absurdly low. I'm not sure it is... I mean, in my country (Netherlands) the average car user drives 13k km per year, in very car heavy countries that's probably around 20k. But here it'd mean a car would last on average 20 years, that's not absurdly low by any standard.

Pretty close. In the US, it is commonly assumed that average mileage per year is 15,000mi (24,000km).

Maybe someone could write a quick script to scrape AutoTrader.com or a similar site and see what the mileage is on cars over 20 years old that are offered. ;-)

Re: Tesla Model S battery degradation data

#82

Post by WillPostForFood »

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…

So if you were optimizing your phone for low battery degradation, when would you charge it, and to what %? If you were trying to keep it around 40%, would a good strategy be to let drop to 20%, and then only charge to 60%, or would you bias it even lower to keep it away from 100%, like a working range of 10-50%?

Re: Tesla Model S battery degradation data

#83

Post by sapienthomo »

hwillis wrote: post #72
peterwwillis wrote: post #37

FYI: Tesla batteries are literally laptop batteries with cell balancing. No secret battery magic going on. You could in theory crack open the pack and replace inefficient cells to get your capacity back. But, I'm assuming this is too huge a PITA for most people.

Sharing a form factor does not mean those two things are the same. The only similarity between laptop batteries and tesla batteries is the can they come in, which is... not important. Please don't open a Tesla battery, the bus is at 600 volts and will kill you stone dead, then start a fire

The cells inside a Tesla S are off-the-shelf Panasonic catalog parts and are identical to parts found in some laptops (and flashlights, and so forth). Tesla's contributions are entirely in the controlling electronics, integration, cooling, etc.

Re: Tesla Model S battery degradation data

#84

Post by sliken »

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.

Buy a subaru next time.

Re: Tesla Model S battery degradation data

#85

Post by graylights »

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…

Sounds like a case of survivors bias. Cars totaled in accidents likely bring down the average.

Re: Tesla Model S battery degradation data

#86

Post by ProfessorLayton »

hwillis wrote: post #57

You lose about 5% capacity in the first 45k miles, then it's essentially flat- 3% in 120k miles. It seems like keeping your charge level at 100% has some impact on lifetime, but lower than 90% looks to have very limited returns. I'll be interested to see how the cycle graph evolves, but right now it looks like batteries will on average make it to 2500-3000 cycles, which is great. There are a number of early outliers…

IIRC no high voltage car batteries are actually charged/discharged 0-100%, even if it reads so from the user's perspective. This is due to significantly increased wear on the batteries when fully charged/discharged, and why a cellphone battery only lasts a few years.

The batteries need to be significantly over-provisioned to extend their lifespan. A Prius, for example, will keep the battery's SOC between 40-80%, and is one of the most reliable hybrids out there.

The same is true for EVs, so charging it till it reads 100% does not mean the battery is at capacity. The same is true when it reads empty.

Re: Tesla Model S battery degradation data

#87

Post by abawany »

fish_fan wrote: post #60
peterwwillis wrote: post #37

FYI: Tesla batteries are literally laptop batteries with cell balancing. No secret battery magic going on. You could in theory crack open the pack and replace inefficient cells to get your capacity back. But, I'm assuming this is too huge a PITA for most people.

I thought laptop batteries are also a bunch of phone batteries stuck together. Is that assumption incorrect? Edit: apparently so.... I would appreciate a reply if anyone has time. I have a difficult time figuring out what about my question could have caused disagreement.

Not an expert and I didn't downvote but from my examination of laptop batteries, they appear to be composed of LIon cells of a standard size, something like 3V cells. Phone batteries OTOH seem to be pretty custom designs to fit a specific phone or range of phones. For e.g. https://electronics.stackexchange.com/questions/156928/repla...

Edit: added link.

Re: Tesla Model S battery degradation data

#88

Post by robryan »

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…

It is more about when the car is costing you enough per year to fix that paying for a new one would be cheaper overall.

Also perceived safety/ convenience, a car might be good for another 100k km but appear unreliable enough that it might break down at any time.

Re: Tesla Model S battery degradation data

#89

Post by kbenson »

user5994461 wrote: post #59
kbenson wrote: post #8

> The red fitted line has a slope above 60.000 km (say 40,000 miles) of 1% per 50.000 km (30,000 miles). I'm going to bring this up because I think it's both interesting, and sometimes it comes up on its own and detracts from the conversation with conjecture (and sometimes harsh assumptions) until covered adequately[1] - different countries have different conventions for whether they use a comma or period for a thous…

It's not just about the thousands separator, the same character is used to separate the decimal part. It's better to use no punctuation at all if you want to internationalize.

Actually, if you want to internationalize for the thousands separator, spaces are likely pretty safe as they are preferred by numerous standards bodies, as well as AMA.[1] That also neatly sidesteps any comma/period confusion for the decimal in large enough numbers, since whichever you see, if there's space grouping thousands, it's that one.

1: https://en.wikipedia.org/wiki/Decimal_mark#Digit_grouping

Re: Tesla Model S battery degradation data

#90

Post by konschubert »

rcthompson wrote: post #31
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?

I think the idea is if you programmed your laptop to never charge the battery past 80% or discharge it past 20%, it would degrade much more slowly, but you would also get about 40% less battery life out of a single "full" charge. Or you would need to increase the battery mass by 66% to get the same battery life. Laptops need to be light enough for a human to carry, while cars don't, and cars are generally expected to…

My Thinkpad supports limiting the max charge to 80%
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