What can we expect of the battery after 8 years ?

What can we expect of the battery after 8 years ?

Tesla has a 8 year warranty on the batteri, 80% capacity if i'm not mistaken. The question is, what can we expect of the battery after those 8 years ? If it's 80% by that time, what about the next 4-5 years after that ? What about performance ?

Elon mentioned that they have a battery pack in the labs that has 500 000 miles on it, it would be interesting to know what that capacity is on that battery and what we could expect of a Model S using that battery, range and performance.

After all, most people doesn't drive long distances regularly and a lot of the emissions comes from the making of the car rather then the fuel it uses. I could definitely see myself using a 8 year old Model S/X as a commuter car. I think (hope) that they will last much longer then a ICE car, assuming that the battery won't die completely.

bp | June 1, 2013

According to the limited warranty for my Model S (which is available for download in the My Tesla Dashboard - battery capacity and range are NOT explicitly warrantied, and that a gradual degradation of the battery is expected.

This may remain the major open issue that Tesla should address, now that they have the service plans, extended warranty, and superchargers announced.

There are so many variables that can affect battery capacity - temperature, charging rates for the battery, charging to variable levels (with the 4.5 release), using MAX range, and using the supercharger - that expecting customers to determine and consistently use their vehicles in a fashion to minimize battery degradation is unreasonable - and the cost of replacing bad battery packs is potentially so high - that this could impact the purchase decision by many of the larger customer base that Tesla is hoping to attract as they continue to ramp up production and sales.

What they should do is amend the warranty to include range - with stipulations that the range will only be protected if users follow the recommended practices (which Tesla can track remotely). And that if batteries then lose range, Tesla will address the issue.

Another option they could consider would be an extended warranty for the battery pack - with capacity guarantees. Whenever the battery drops below a certain capacity - Tesla would evaluate the battery pack - and then replace as much of the battery as needed (hopefully the degradation will be isolated to a relatively small number of bricks).

One of the great benefits of the Model S design is the modularity of the battery pack - and Tesla should be able to take advantage of that design to address this last major area of concern by owners and potential customers - capacity anxiety.

carlgo | June 1, 2013

Can these batteries be refurbished in any meaningful way? The metal stuff could be recycled like anything else, but what about the battery ingredients? Anything in there that is valuable?

People have mentioned them being repurposed as solar energy batteries, but wouldn't a worn out car battery be just as useless in your house?

DHrivnak | June 1, 2013

Yes the batteries can be both recycled and repurposed. But hard to know for sure until we actually have old batteries in quantity.

On recycling see this:

Brian H | June 1, 2013

"worn out" is an arbitrary decision. 70% remaining is the industry LiIon standard, but the decline is slow beyond that. Lots of use left; decades in a static application, for sure. Note that at that level an 85 still has the capacity of a new 60, and a shallower decline rate.

Joshua Burstyn | June 3, 2013

@ Brian H:

"Note that at that level an 85 still has the capacity of a new 60, and a shallower decline rate."

Indeed. Considering all I need is a solid 120km for my round-trip to work every day, this vehicle could conceivably last me many more years than the 8 years of warrantied driving. My 2008 Hyundai Accent has 157,000km on it and is on its last legs... so much for battery concerns - my ICE vehicle is less reliable.

Brian H | June 3, 2013

120 km! What's that, about 75 miles? Piece of cake.

BjörnF | June 4, 2013

Here's an interesting discussion about the batteries that Tesla supposedly are using:

The interesting part is the 60-90% SOC graph where it shows that you'll get 80% capacity after 3000 cycles. 30% charge in a 85 kWh Model S lets you drive around 80 miles (EPA), something that very few do on a daily basis. But even so, using that number, 80 miles/daily every day of the year, the 85 kWh Model S will still have 80% capacity after 8.2 years.

In Sweden, the average distance a car is driven/year is ~12000 km or ~7300 miles. (3000*80)/7300 = 32.8 years. The average lifetime of a car in Sweden is 20 years.

So if i did my math/thinking correctly, the 85 kWh Model S should last the lifetime of a car.

SamO | June 4, 2013


You did your math/thinking correctly.

Brian H | June 4, 2013

(Un)fortunately, Swedish drivers, like all others, will discover that they drive much more than they used to (because it's so enjoyable) so the lifetime will be much shorter.
:D ;(

BjörnF | June 4, 2013

I meant to say "the battery of the 85 kWh Model S should last the lifetime of the car". Anyways, doing the same math on the 60 kWh pack -> 25 years. Hmm, i wonder what the smallest battery pack for Generation 3 will be, 50 kWh ?

@Brian H: That's probably true :-)

Joshua Burstyn | June 4, 2013

Supposedly the NMC type lithium cells used in the 'S are very durable even as compared to the previous generation 18650 units in the Roadster.