What positive thing do you expect from this update? Do the potential upsides balance the potential downsides?
It might prevent your car from catching on fire and burning to a crisp.
As y'all may know, I've been avoiding updates for literally *years*. They finally (just last update) fixed the worst regression with USB music -- you can now play folders in the correct order, yeehaw. But this one seems to be an actual safety update (unlike most of 'em) so I kind of wanted to get it.
And I got lucky, my cars were apparently not among the affected / range-reduced cars (can't be *sure* but it seems like it).
My second car was actually driven back from Toledo, and Supercharged to 100% more than once, while on the new software, and its range is still fine.
It seems that Tesla is using the DVA (differential voltage analysis) detection system to detect lithium plating.
I started doing some research on this. Lithium plating apparently is much more likely with high speed charging, which I do very rarely, and also more likely in colder temperatures. While I drive in cold temperatures a lot, I have only Supercharged during the summer, since road trips in the winter are not my idea of fun. I have high regenerative braking loads because there are very steep hills here, but Tesla was always limiting regen a lot with cold batteries, and I'm guessing they were probably limiting it enough to prevent lithium plating. So my odds of having significant lithium plating are low. The previous owner of my second car Supercharged more often, but again primarily in the summer, and had no hills; and he seems to have avoided charging to 100%.
However, the DVA system appears to be unable to detect the plating until some charging cycles have passed, and I tend to be charging very shallowly through a narrow range, so I might end up with noticeable range loss later. I doubt it though -- it appears to primarily affect people who do a lot of Supercharging particularly in cold weather (and of course with the original all-graphite anodes).
Those of you whose range has dropped -- I understand why you're frustrated. But you don't want your cars to catch fire, I assume.
Most of you also probably don't have a warranty claim. Back when I bought my car in 2013, nobody knew how much range degradation was going to happen. Tesla wrote their warranty to avoid covering degradation unless it was extreme. At the time, the chatter was of degrading to 70% of rated range over the course of 8 to 10 years. (Tesla *has* replaced batteries where the range dropped below 70% of original rated range during the warranty period; they had to admit that those were flat out defective.)
Teslas have, on the whole, done better than that projection on range degradation over time. Even for owners with this "overnight" 10% - 15% drop,... they're mostly still doing about as well as that, so people with older cars who got hit with a range reduction still have more range than we expected back in 2013. That's going to make a warranty claim pretty hard.
And furthermore,
it isn't really an overnight drop -- the safe range has been dropping slowly and continuously, due to a deterioration mode which was known and expected back in 2013, but Tesla's system wasn't detecting the drop in range. So it was a continuous drop in range, due to lithium plating, but Tesla's software wasn't detecting that, and now it is, so the
reported drop is sudden.
Someone with a more recent car who saw a sudden drop may have a better claim since nobody should be seeing a 10% drop in range after 1-2 years.
Anyone whose range is less than 70% of original EPA rated, and still within the 8-year warranty period. probably does have a claim too. While there was no specific "70% warranty" (as there was with Model 3), 70% was what people were talking about when the cars were originally delivered, and it's a good benchmark.
TL/DR: in my opinion, those who see range drops have actually had slow deterioration from lithium plating over time, but the Battery Management System wasn't detecting it properly before, and now it is. The update actually is a safety matter. If you don't update, the BMS may believe that it's safe to charge the battery higher than its actual capacity -- overcharging is, of course, a standard way to set lithium-ion batteries on fire, so if you don't update, don't charge your car to 100%. If your rated range goes below 70%, you probably have a warranty claim, if not you probably don't.
