Battery warranty

Any ideas how the battery warranty will work? Let's say that after 7 years and 70,000 miles the range of the car has decreased to 75% of its original 230 or 300 miles. Can I claim a new battery under warranty? What if the range had decreased to 50%? 20%? 5%?

What other symptoms would a battery exhibit that could lead to the need for replacement under warranty?

When I talked to a Tesla rep at the Geneva Motor Show in March, I asked the same question. Obviously, the fine print was not yet finished at the time, and the rep would not commit to any hard figures, but he stated that Tesla's warranty refers to a "practically-new" state of the battery. The warranty not only covers degradation in capacity, but also degradation in power delivery which becomes visible in higher 0-60 times.

In any case, the rep confirmed that 70% of the specified capacity cannot be considered "practically new" and would be covered under warranty.

When I was at the Menlo Park store last month I specifically asked about battery warranty. I was told it would not cover degradation at all. The battery would not be warrantied for 70% after 8 years or even X% after N years. I was told residual capacity was too dependent upon individual driving characteristics to warranty and that the battery warranty would cover power output but not residual capacity. I asked several times to be sure I heard correctly that percent of original capacity would not be covered and got the same answer each time. Hopefully the rep was misinformed but he was extremely knowledgeable in all other areas so one has to wonder if he was correct about this too. I hope he was mistaken. We will know soon enough.

I asked this question when I was at the NYC store for the technology tour a few months ago, and also of my Tesla rep via email, and got the same answer both times-

"The official warranty has not been published yet, but should be available soon. The battery warranty will cover parts and workmanship defects, but will not cover natural degradation over time."

I guess the question is "unnatural degradation", which presumably would trace back to parts and workmanship. Considering Tesla would have access to the log, it would be possible to establish whether unusual capacity drop was due to owner abuse!

Workmanship warranty on the battery is useless by itself unless it also includes a number for the residual charge. That residual charge number should be in the 80% or higher range in my opinion at the end of the warranty period.

What do you think Tesla should say to someone who keeps their car fully charged - against Tesla recommendations - every day, thus reducing the capacity?


I thought Tesla wanted owners to charge the car every night? Wouldn't that keep the car fully charged every day?

Tesla suggests you plug the car in every night. But you get to set how you want the car charged (at least this is the way it is reportedly done in the Roadster). If you want the full range for the next day, you put it in Range Mode which fully charges the battery at some cost to its lifespan. For everyday use you use a different mode which keeps the car at something more like an 80% charge maximum, thus lengthening the life of the battery pack.

@EdG Thanks for the explanation. I typically drive less than 20 miles a day during the week and slightly more on the weekends. I guess I won't be using Range Mode that often.

@EdG. Thx for that info. I will have to do some re-calculation now since 80% may have some consequences. I drive +/- 160 km minimum a day at 120km/h (100 miles at 75m/h). No detour or going to the city for grosseries are included. Comes closer to empty than I thought ...

Don't hold me to the 80% figure. All I know is that it's not 100%. And it may be different for the S than the Roadster.

For what it's worth, remember: the amount of savings you get for slowing down is dramatic.

I do not expect Tesla to warranty the charge capacity. That would be like warranting tire wear. I can take a year old tire out smoke the tires until all the rubber is gone and drive back in for new ones..... that doesn't fly. Likewise I can run my battery down to 2% every day and supercharge everyday. That will probably kill the battery in a few years..... not going to be covered under the warranty.
Now if you drive the car for 7 years normally and the battery has some low charge capacity, lower than other cars, then they will probably say it's a warranty issue after looking at the logs for the your car.

You could probably recharge nightly on a 110V circuit! Or a couple of times a week on a 220V.

"No detour or going to the city for grosseries" -- Jeez, sounds kind preverted! I doubt many people want grosseries in their Model Ses. They can be kinda gooey and gluey!

Will you be doing any shopping for groceries, tho'?

@BrianH : thx for pointing that out.

If you try to spell my name correct, I will try to write my comments correct in this foreign language called English...

sorry 'bout that! There are a couple of stephens around, force of habit.

(I'd never seen "grosseries" before, and it was such a compelling image I couldn't resist.)

Brian H, if there's any typo which you can resist commenting on, as you seem to imply by your above post, please let me know which it is.


Lots of issues and stumbling blocks with a battery warranty, apparently. I can see why it's taking time to settle on a policy. Does anyone know what e.g. the Leaf battery coverage is? Or the Ford Focus EV?

And what is the wording of the Roadster battery policy?

I understand the issue with people abusing the battery in their Model S but if you follow regular charging procedures and the car only had 20% of it's original capacity left at the end (I am just trying to make a point with the 20% number), I want to make sure they will cover this under warranty. With making sure I mean in writing!

And what is the wording of the Roadster battery policy?

And... are there typos in there? :-P

That does make sense gjunky. It should stand to reason that a battery at 20% anytime over the warranty period should have some kind of manufactures defect in it if it was charged reasonably "normal". I would think they would replace it.

They may deduct for mileage.... kinda like tires tho... That's what I am waiting to read... or not. If you had the battery for half the warranty time they might only give you half the cost for a new battery.

Small things amuse ...

Yes, 20% left is almost unusable. That's also almost impossible under normal usage without a significant battery flaw. If the warranty covers anything, it would surely cover that.

My guess is that the warranty may take the form of replacing individual sheet or cells in the pack if they are found to be weak. This would be part of annual service and/or might be detectable by system monitoring and fixed as needed. Keeping the whole pack optimized should reduce the likelihood of major capacity loss at the end of 10 years. I hope!

Do you think the packs can be popped open like that? It would almost be a factory-level service job, I'd think.

I don't know. Just making it up as I go.

Because the pack is supposed to be able to be replaced in somewhere between one and five minutes (depending on where you've read it) I would think it would be relatively simple (with the right equipment) to drop the pack, open the section with the weak sheet and replace it. This should be a far simpler job than in the Roadster.

It might be less labor to just replace the pack and send the bad one off to be refurbished. Pulling a battery pack out of a laptop is easy. Opening up that battery once it's out of the laptop is rather difficult.

I agree with Sudre_ here. Replacing a faulty battery inside the battery pack can't possibly be a very fast job, there are electronics and cables to mess with and all of that in high-voltage environment. Also where there are one sheet of faulty batteries it is probable that there are others not yet giving out symptoms of failure. Much easier to just replace entire pack and send the faulty one to factory to be tested and repaired.

You guys are probably right. I was thinking that the sheets just snapped in from the top similar to how a hard drive snaps into a Mac Pro.