[The original version of this post was written as a response on SpeakEV.com forum a few days ago.]
All EV batteries degrade. The important thing is to warrant what is acceptable degradation and what is not. Lacking the guidelines sucks, for lack of a better word, but it isn’t fatal. It’s just part of the equation.
We own our two Teslas and I am disturbed by Kevin Sharpe’s Experience, but the published guidelines did say 30% in five years… All this means is caveat emptor.
Our Roadster was already five years old when we bought it, so, I would love to know what I get with the CPO Warranty or what we would get with purchase of the 400 mile upgrade batteries. How long will the car run up to 400 miles.
On Twitter, Nikki Gordon-Bloomfield (@aminorjourney), has postulated that battery packs are the consumable portion of EVs.
An electric car battery is a consumable item: discuss.
— N. Gordon-Bloomfield (@aminorjourney) September 9, 2014
Like it or not, she has a valid, and yet expensive point. However, unlike gasoline/petrol we don’t have to replace every time we charge, only as long as the batteries are useful for us. In which case, it’s eventually time to change.
Tesla’s Roadster warranty had defined that in a binary situation, so, if one were to make the case to swap it out under Tesla’s warranty, it can’t be done based on degradation, it is because of a full battery/system failure. This sucks, unfortunately that is what was warranted.
Now the valid question for Model S owners (and guess what, I’m one of those too) is what about our battery packs? Well.. We’ll need to see if degradation is covered.
[This is where new information, or should I say OLD information was posted on the Model S Warranty (including the current "unlimited" Model S warranty) also specifically excludes battery degradation. As was pointed out on both TeslaMotorsClub.com and SpeakEV.com forums, see page 35 and 36 (pages marked 33 and 34 due to other unumbered pages) of this PDF.
The particular language excerpted from the PDF link above:
"The Battery, like all lithium-ion batteries, will experience gradual energy or power loss with time and
use. Loss of Battery energy or power over time or due to or resulting from Battery usage, is NOT
covered under this Battery Limited Warranty. See your owner documentation for important
information on how to maximize the life and capacity of the Battery."]
Otherwise, prepare to save for a replacement battery pack in the future. I have always recommended (often in the early years of my blog and in forums) that new EV owners put aside half of what their “fuel” savings aside for the future need to buy a replacement pack IF they do as I do with most of my cars (and that’s keep them for a LONG while) (my hybrid garage has a 2001 BMW X5, my non-green, I have to get to the mountains for Fresh Snow car.)
Guess what, that advice still holds. I’ve lost five miles of rated range from 265 max charge to 260 max charge. Ideal miles lost 3 miles. And I’m less than a year AND over 20,000 miles. However, it must be noted that Tesla delivered the car with greater than 300 miles of ideal miles and I’m just around 299-300 miles ideal now. Yes, it’s hotter in California than the UK and we do have active thermal management, but it’s still the case that degradation happens. I still made it to Barstow, then Vegas on SCs. The car is still awesome, the Roadster is still fun, and Tesla is not perfect. I never thought they were (if BMW i didn’t piss me off as much, I might still have picked up the i3 I ordered.)
[end of almost original forum post.]
After a day of mulling over the lack of battery degradation and comparing the Nissan Warranty, BMW’s match of said warranty and the fact that Tesla’s two competitors include battery degradation, I believe that it is time to call out Tesla and tell them that they need to include battery degradation into the equation. Spell it out. If it is the same specifics as the 2006 Roadster blog post that says 30% after five years, then that’s what it is. It’s not very impressive and I would ask that CPO Roadsters be provided with a modification to this, but that’s at least something. Additionally, AFTER providing such guidance, give us a price on replacement batteries. Nissan gave a $5,500 rate for their cars, why can’t Tesla do it now? With the pending Gigafactory, surely the economics only gets to improve.
C’mon Tesla, be awesome again!