I do know that I would not spend money on a battery replacement because of this issue, were it impacting my car. Even a cheap battery (let us say $5k) would have to be correcting a really serious charge rate degradation for it to be worthwhile for me. I can handle an extra hour on my annual road trip a few years down the road. Of course YMMV and I agree that it would be very nice if Tesla offered pack upgrades in the future. I can dream for a 120 pack five years down the road.
I may have posted this way up-thread, I've certainly mentioned it before, so apologies if I'm being repetitive.
Agree,
@DarkMatter. When trying to decide in late 2013 whether to take the leap of faith into a) EV's, and b) a very expensive long-range EV, my reasoning was thus
- At the time, Roadsters had 5-7 years on the road, and the "worst" battery degradation measured still had more than 90%
- I knew that Tesla had put a lot more research into Model S battery management since the Roadster
- The S85 had a range of 425km/265mi new; if degradation after 8-15 years was as bad as 80% that would reduce range to 320km
- OTOH, the supercharger locations in North America were increasing like gangbusters, so the likelihood of needing more than 320km on a road trip was reducing rapidly
- Battery prices were likely to reduce, so if I decided after 10 years that 320km wasn't enough, I would likely be able to replace the battery for similar cost of replacing an IC engine (i.e., $5k-$10k). Note that's a big "if"... 320km may be all I need even for long trips.
Given all that, I decided to take the leap and think of the S as my "permanent car". Current results: 4+ years in, 100,000km+, max range is ~406km or 4.5% degradation, and it's been at 4.5% for the last two years or so. So performance is much better than the poorer cases I was imagining, battery prices are still (presumably) dropping, and I still love how the car drives especially on long trips.