Thanks for the reply. I did some poking around and the answer to “what is the lifespan of an EV battery?” seems to be that we don’t really know yet. But so far they seem to be exceeding expectations, and 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. Most of the EVs out there are currently on this plateau.
Here’s a site with some interesting data:
https://www.recurrentauto.com/research/how-long-do-ev-batteries-last
It’s by an organization that tracks battery data of its members’ EVs. They currently have over 15,000 members they are collecting data on. The linked page has plots showing driving range versus odometer miles where you can see the falloff trends in various EV makes and models.
Interesting Autoweek article on battery life:
https://www.autoweek.com/news/a39713122/predicting-how-much-range-ev-batteries-lose-over-time/
Tesla uses four kinds of Li batteries. The 18650 you mentioned was used in early models and is still used in the luxury Model S. The more common Model 3 is now two generations beyond the 18650 (which is an NCA type...nickel cobalt aluminum). Recently they’ve started using a new type of battery (LFP...lithium iron phosphate) that doesn’t use either cobalt or nickel and is much easier to source. It’s also easier to recycle and much less prone to thermal runaway.
https://insideevs.com/news/587455/batteries-tesla-using-electric-cars/
This article says LFP is intrinsically incapable of self-induced thermal runaway:
https://www.powertechsystems.eu/home/tech-corner/safety-of-lithium-ion-batteries/
On eBay it looks like 2013 Tesla model S’s sell for between $10K and $20K depending on condition:
Based on what I’m reading, the price of replacement batteries has been falling and there’s an active market for refurbished and used batteries. Replacing an S battery looks like $20K on the high end for a brand new battery, but I’m also seeing people paying a third of that for a refurb battery with a warranty.
A factor in extending EV battery lifespan, and part of what separates EV batteries from Li batteries used in other applications, is apparently the active cooling that’s designed into EV battery packs. Apparently Li batteries are especially prone to degradation when their temperature isn’t controlled.
It may not be possible to replace your battery yourself and then insure the car. Unfortunately, I believe that many of the reports that you are putting your faith in are from advocates who are not sharing the whole truth.
It is a little like my 2001 Astro van which has 240,000 miles and is still going strong. The trip computer has always reported that the MPG is about 10% greater than it actually is.
Even in the article from Autoweek, "When the car was new, Neary would see a rated range of 252 miles after a full charge. “But now I don’t trust the car beyond 100 miles of range,” he said. The range degradation combines a number of factors. Now, when fully charged the gauge shows 174 miles. “And for the last two years, I can’t drive to an indicated zero miles anymore,” Neary said. “With a rated 30 miles left the car will tell me to pull over and shut down.”
These vehicles do not give an accurate indication of how much range is really left. At least my Astro van gives me an accurate indication of how much range that I have left. You are certainly free to put your faith in whatever research that you want to. I would warn you however that confirmation bias is something that we all struggle with. Most people you meet who have a few years of experience regardless of whether they are true believers or not will admit that electric vehicles seldom come very close to their advertised numbers after just a year or two. It is the nature of the beast.
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.
I did find a couple of links that said basically what you have, but they were not referring to battery packs which contained a large number of cells. I believe that the problem is that when one cell fails completely and it could even be the protection circuit... the entire battery pack can typically fails completely, and they are often not rebuildable especially by the end user and not worth a professional’s time to mess with by that point.
As far as buying used batteries that have been “refurbished” this can be a very frustrating game. From experience, they typically are not worth messing with in most applications.