I did want to thank you for sharing your links... I am a little busy today but I did try to go through them all. There was some good information. I did not see anything that seemed to be responsible for your statement, “ the pattern doesn’t seem to be that they fail suddenly and become unusable. Instead there seems to be a falloff early on which then flattens into a plateau with a slow gradual decline.”
This actually does not completely contradict what I said in post 26, “When they have faded to 50% capacity, they are likely to quit working completely within a short period of time.” The long fading period is to about 50%. Once they fade to around 50% they do not tend to remain useful for any purpose for very much longer. Typically, they quit working completely not too long afterwards. This has been my experience with various types of lithium-based batteries over a fairly long period of time... They go downhill for quite awhile; you think that you will be able to keep using them and then they stop working completely.
I am a person who uses things until they are completely warn out and throws away nothing if it still has some possible uses or contains parts that could be salvaged. But over the years I have had to take a lot of lithium-based batteries to the hazardous disposal drop-off location of our city dump.
I am however interested in where you picked up your impression that lithium-based batteries slowly fade to nothing.
First off, I’m not an EV true believer by any stretch. But I am trying to get a clear understanding of their pros and cons rather than rejecting them outright. This means acknowledging the areas where they’re successful.
The plots in the first page I linked show the decline in range versus mileage for various EV makes and models based on data collected from 15,000 or so vehicles. You can see in most plots there’s an initial loss of range in the first 20K or so miles and then it flattens out and continues on with only a very mild loss of range per year. This is a consistent pattern across nearly all of the plots.
The long fading period isn’t to about 50%. It’s to more like 90%. The Tesla Model 3 with the mid-tier 75kWh battery starts out with a range of about 300 miles and then settles to a range of about 280 miles. The graph is very flat from about 20K out to 100K miles on the odometer. The plots end at 100K miles, probably because they don’t much data on cars beyond that mileage at this point. The trend of the data shows no sign of a sudden inflection towards failure.
An interesting statistic is that, industry wide, only 1.5% of EVs are requiring battery replacements within the warranty period, which for the Tesla Model 3 is 8 years or 150K miles. So at 150K miles most Tesla 3’a have at least 70% capacity (70% is the threshold for replacement) and presumably are still on the flat part of their decline.
The guy in the Autoweek article whose EV was acting strange had a vehicle with over 200K miles. The article suggests his experience may be anomalous since studies have found vehicles with 200K+ miles to have only a minor loss of range.