Tesla has updated their warranty coverage for Model S and X cars, and it’s a mixed bag for owners. The warranty now explicitly covers battery degradation and capacity loss, guaranteeing that the battery will retain 70% capacity through the warranty period. But Tesla also removed their famous “infinite mile warranty” for battery and drive unit and replaced it with a limit of 150,000 miles — still plenty high for most (but not all) scenarios, but not “infinite.”

More controversially, Tesla explicitly stated that “changes to the performance of the battery due to software updates are NOT covered” under warranty, likely due to a situation last year where some owners saw sudden range drops after an update.

Those sudden range drops actually resulted in a class action lawsuit. Tesla responded, stating that the update was done to protect the battery packs.

In the full new warranty document, Tesla says that sometimes the car will get “updates to protect and improve battery longevity.” These updates, if they result in “noticeable changes” to the battery, are not covered by the capacity warranty.

In addition to this range drop for some cars, Tesla software updates have also given more power and more range in the past. These have been due to optimizations in motor and inverter control software, and also simply due to changes in the way that Tesla calculates range.

Since Tesla’s range estimates “are an imperfect measure of battery capacity because they are affected by additional factors,” Tesla says they reserve the right to decide how capacity is calculated.  Tesla has previously used a measurement called “calculated amp-hour capacity,” or CAC for similar purposes.

Battery degradation warranty extended to Model S/X

Tesla added a warranty against battery capacity when the Model 3 first came out. The warranty triggers if the car has less than 70% of original capacity before the end of the eighth year, 100k/120k mile warranty period (mileage depends on battery size).

The new capacity warranty doesn’t seem to apply to the original 60kWh Model S, manufactured before 2015. Those are now covered by a similar eight-year, 150,000 mile warranty, but without the degradation coverage. These cars were originally covered by a 125,000 mile warranty, which looks like a retroactive increase.  Though the change to 150,000 miles may just be an error on Tesla’s part, since it’s not specified in the actual warranty document, and only on the website (see below).

Here’s the basic form of the old and new warranties (old warranty scraped from archive.org, with differences in bold):

Old warranty:

  • Model S and Model X: Eight years (with the exception of the original 60kWh battery manufactured before 2015, which is covered for a period of eight years or 125,000 miles, whichever comes first).
  • Model 3: Eight years or 100,000 miles, whichever comes first, with minimum 70% retention of battery capacity over the warranty period.
  • Model 3 with Long-Range Battery: Eight years or 120,000 miles, whichever comes first, with minimum 70% retention of battery capacity over the warranty period.

New warranty:

  • Model S and Model X: Eight years or 150,000 miles, whichever comes first, with minimum 70% retention of Battery capacity over the warranty period (with the exception of the original 60kWh battery manufactured before 2015, which is covered for a period of eight years or 150,000 miles , whichever comes first).
  • Model 3 and Model Y Standard or Standard Range Plus: Eight years or 100,000 miles, whichever comes first, with minimum 70% retention of Battery capacity over the warranty period.
  • Model 3 and Model Y Long Range or Performance: Eight years or 120,000 miles, whichever comes first, with minimum 70% retention of battery capacity over the warranty period.

Batteries degrade over time, and a battery that’s several years old and has been through many charge cycles won’t hold a charge as well as a brand-new one.  Most consumers have experienced this with a phone or laptop.

Electric car batteries are much bigger and more complex than phone and laptop batteries. Many of them (like all Teslas) have active cooling systems to help keep the battery at a healthy temperature. Some also disallow owners from fully charging or discharging the battery, since keeping batteries at 100% or discharging them to 0% tends to cause faster degradation if done all the time. Tesla recommends “daily” charging to 80-90%, and plugging in ASAP when your battery is very low.

But these are small optimizations, because it turns out that battery capacity degradation isn’t all that bad in electric cars. Crowdsourced data collected by European Tesla owners has shown that Teslas can expect to keep about 90% of their capacity even through the first ~300,000 kilometers (186k miles) on average.

This sort of data has made manufacturers more confident of long-term EV battery capacity. Warranties that cover battery capacity are still somewhat rare in electric cars, but are becoming more common.

The Leaf started warrantying against battery capacity drops a couple years ago too, and some new cars like the Mini Cooper SE have a similar battery warranty.  We’ll expect to see this on more and more electric cars as time goes on.

Model Y Warranty

Tesla also added warranty information for the upcoming Model Y, which starts shipping next month.  Warranties for the Model Y will be the same as the Model 3, much as how Model S and X warranties are the same.

Electrek’s Take

When we started hearing about last year’s range-drop issue, our reaction to the situation was that Tesla could have avoided a lot of anger by being more transparent and communicative about their changes.

If Tesla can find way to update the software to get better longevity out of batteries, this is mostly a good thing. But nobody likes to see dropping numbers, and especially when the reason behind those dropping numbers wasn’t communicated properly.

Personally, I think EV owners in general (and particularly Tesla owners) tend to overreact to small changes in range numbers. Like Tesla says, the range number on your dash is imperfect. If it fluctuates a few miles from day to day, that’s normal.

Besides, range doesn’t really mean much since it’s so heavily affected by how you drive. You’ll do more for your range by just slowing down a little bit, or using the aero wheels (which I think look better anyway, cough), than several years of degradation. And there are very few owners who will see any meaningful difference in their driving patterns if their car goes from 315 to 300 miles of range, and very few who will complain if their car does the opposite.

But that doesn’t change the shadiness of the significant, sudden range drops to certain cars without communication. It’s understandable that owners would be mad about that, and this new change that Tesla has made to avoid future similar controversies seems shady as well. The proper solution would be to commit to communicating better in the future, not to tell some of your rightfully aggrieved customers that, effectively, “if this happens again, you have even less recourse than before.”

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