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Tesla model Y 4680 battery pack not very serviceable!
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tom66:

--- Quote from: nctnico on August 14, 2022, 10:36:54 am ---But you have to factor in the nature of the device you are deriving statistics from. At some point Li-ion batteries start to lose capacity exponentially. You can imagine a straight line going down gradually but that is a fantasy. So again: there is data missing to draw a definitive conclusion. The graph should have included error bars; that would show an entirely different picture.
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Do they?   Why would cell degradation be exponential and not just linear?  The cause of Li-ion deterioration is contaminants building up at the SEI layer, which limits the amount of charge and discharge progressively.  You can model this with coloumbic inefficiency; Panasonic chemistries have a very low CI figure.  I see no reason this has to be an exponential failure, especially if the cell is kept within reasonable temperature ranges and has a stable chemistry.  Heck, even the shittiest Nissan batteries have near-linear degradation. (https://flipthefleet.org/wp-content/uploads/2018/07/decay_comparison.png)


--- Quote from: nctnico on August 14, 2022, 10:36:54 am ---That is not the point  :palm:  The point is that cars (or any item) can have defects. Some are more costly to fix than others based on construction. Looking at the graph the chance that you buy a Tesla with a bad battery is around 1 in 1000.
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And I'm sure there's a 1 in 1000 chance of something bad happening with an ICE engine - owning a car is always a risk.  I know people with ICE cars, perfectly serviced, which have burned to the ground in the night for no good reason.  Or cars that randomly throw a rod just outside of warranty.  I do agree that Tesla needs to make their packs more serviceable but I don't think the chance of failure is so high that it can't be mitigated.  There will certainly be a good after-market for battery warranties, and battery service, once EVs become more dominant, just as there are gearbox/engine rebuild companies now.
Someone:

--- Quote from: tom66 on August 14, 2022, 10:14:36 am ---
--- Quote from: nctnico on August 14, 2022, 10:07:26 am ---There are a whole bunch of outliers in the graph that show you can get seriously unlucky and buy a lemon battery pack. Also the amount of data for high mileage numbers is minimal.

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Boy, it sure is good that there's an entire field of statistics based on the idea of statistical distributions that allows you to infer data into the future. 

And of course, everyone knows lemon products are not seen in any other field other than electric cars.

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Also, graph cutting off the y axis at 85% remaining capacity. Not 0%, still completely usable! Given things like fast charging are going to reduce capacity it is not surprising that there is spread. Given they are chemical batteries (without a significant opportunity for binning??) the spread is impressively small! Prius' with their more heavily cycled battery were getting 150,000 to beyond 300,000 km before requiring replacement.
PeteH:
Some additional data here (Tesla Model 3, Long Range, 2018). DC fast charging (supercharging) about 6.7% of total kWh charged. Range at time of purchase was rated at ~499km.

Edit: added another 3rd party tool's data.
tszaboo:

--- Quote from: Psi on August 14, 2022, 03:23:57 am ---
--- Quote from: tszaboo on August 13, 2022, 09:08:32 pm ---
--- Quote from: Coordonnée_chromatique on August 13, 2022, 08:54:51 pm ---
--- Quote from: tszaboo on August 13, 2022, 07:59:27 pm ---Realistically, the battery lasts longer than the car.
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Could you give some examples of reliable statistics please ?

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Sure, but you could just google it yourself.
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--- Quote from: SiliconWizard on August 13, 2022, 09:28:48 pm ---Over 90% after 250 000 km... yeah. Really? ::)

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Hm.. i'm not sure if that graph takes into account the cars that have software limited battery capacity.
I mean the cars that received a large battery pack but were sold as lower range cars with range software limited to match the model that was purchased.  I'm pretty sure those cars use the extra capacity to compensate for aging, so they appear to last forever because you don't notice any loss in range until the pack is like 60% deteriorated and it starts eating into your software usable range. Also those cars don't get their batteries charged/discharged to as wide of a voltage range so that helps a lot too.

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The toyota prius battery pack was microcycled for at test. They used the usual between 40-60% DoD that the car is using for it's ~2km range. They did as I remember over 100.000 cycles with it, which is like 200.000 km electric only.
Most EVs have better lithium batteries. And it's not like your cal becomes unusable with a 80% battery pack. Even Nissan Leafs which had badly designed batteries with insufficient cooling often have 80% left after 6-7 years.
tom66:
My GTE battery is going on for 1200 cycles (25 miles range, 40000 miles but some on petrol so assume 30000 miles on EV) and still shows capacity of around 93.5% of original.  That pack is discharged up to 10C under hard acceleration and regen is ~5C peak.  It is however liquid cooled and uses Panasonic cells.  I am pretty sure even a PHEV pack could do 200k miles to 70% capacity although this might be a good reason not to get a PHEV over BEV - I would imagine the BEV battery will last longer (but the PHEV does have the engine as a backup)
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