Tesla vs Leaf battery degradation

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barsad22

Well-known member
Joined
Jan 14, 2011
Messages
142
Location
Berkeley, CA
Hello --
I just came from a Tesla S test drive, and asked the 19-year-old sales guy some tough questions about Tesla battery degradation over time.
I come at this as an owner of a 2011 Leaf with 39K miles, and a 79.4% capacity confirmed by Leaf Spy.
So when he told me that Tesla claims a maximum 0.7% per year degradation (let's call it 5% over 5 years), my jaw dropped. When you consider the 8 year battery warranty and a promise to replace any cell that doesn't meet the 0.7 standard each year, it really makes Nissan's numbers and lame warranty (ie, come to us only if you hit less than 70% capacity) look terrible.
My question is why Tesla beats Nissan by 4X or more on the degradation score? Or do we think this is unrealistic for Tesla to claim those figures?
Out of these three explanations for the Tesla-Leaf battery gap, which one has the most impact:
- Tesla has a thermal management system (does it work during the charging cycle or only while the car is running?). Leaf does not.
- Tesla uses LiCo battery, Leaf uses LiMn.
- Nissan battery manufacture is lower quality than Tesla.

Other reasons? If the Tesla degradation is really this low and Nissan keeps making cars that essentially wear out in 5 years, I don't see how the Leaf can compete. When I bought the Leaf I was fully aware of the 20% loss, but I underestimated how important that 20% is to our daily destinations. There are many places we could go to in 2011 that we cannot go to in 2015.
The biggest problem is really transparency, it always has been. If consumers have to guess at degradation numbers or trust sales people to give honest estimates, we aren't going to have solid information to make an EV choice. This drives away potential buyers and hurts the overall EV movement.
Best,
Josh
 
Tesla does not use LiCo, but uses NCA. (li cobalt has excellent calender life but woeful cycle life, it used in laptops and Tesla roadster - opposite behavior to LEAF 11-12 batteries)

Tesla and Nissan have both improved their batteries considerable over last few years, Tesla started good and is now excellent.
The figures given for Tesla seem reasonable.
Nissan batteries don't burn like Tesla's though, but the Tesla is an authentically safe car.
 
As a relative late-comer to the EV world (have now been driving a 2015 Leaf for over 7 months) it shocks me to see some of the degradation stories from early Leaf owners. I am no battery expert, but can only assume Nissan learned from early mistakes and made significant changes to the Leaf battery after the first few model years. Anecdotally, it seems 2013 and 2014 Leaf batteries do not degrade as quickly as the 2011 and 2012s do. And now that I have Leaf Spy I can confirm I still have 100% SOH on my 2015 Leaf with almost 7k miles on it, having now driven through most of what has been a very hot summer in Georgia. So far I am quite pleased with the Leaf, although time will tell if that continues.
 
The 0.7% number sounds like a bit of a stretch, unless they are talking about their newest batteries.
Anecdotally, it seems about 2-3% the first year and then about 1%/year after that.
I've heard their latest batteries use a bit of Silicon, which seems to improve power and longevity. That may have been what the employee was talking about.

As for the difference, my personal opinion is that the biggest factor is the lack of a good temperature management system.
This affected Leafs in the southwest far more than Leafs in Minnesota. Many early Leafs up here have experienced very little degradation.
As you said, both companies are improving their batteries over time, so I would expect longer lasting batteries with each new battery itteration.
 
Indeed, it appears that Tesla has gotten remarkably better with batteries since the Roadster and RAV4 EV.

It's a bit silly to compare to the first generation LEAF, which is one of the worst for degradation (compared to ALL of the current EVs on the market).

My 2012 Toyota RAV4 EV is at 12% degradation in about 3 years with 53,000 miles (Tesla drivetrain and battery). I expect to be at 20% degradation in 6 years with 100,000 miles.

Because the car is fully capable of 100 miles of real range, even with 20% degradation, it's doubtful that will be much of an issue for me.

The singular biggest issue with the RAV4 EV was the lack of CHAdeMO quick charging, and our company fixed that with JdeMO.

With 12% degradation, I was quite capable of driving 600 miles in one day from San Diego to Santa Rosa, California, using only public CHAdeMO stations. I could do it again at 20% degradation.
 
Anecdotal evidence has shown that Tesla's figures are about right... As you stated, their TMS likely has a lot to do with it...

barsad22 said:
My question is why Tesla beats Nissan by 4X or more on the degradation score? Or do we think this is unrealistic for Tesla to claim those figures?
 
You can't ignore the fact that a Tesla costs 2-3x that of a Leaf! Nissan made many design choices (discussed ad nauseum on this Forum) to make the Leaf available "to the masses". They have (finally) improved their battery technology and offer it as a replacement/alternative to those degraded by heat (whether you agree with the warranty terms or not). I like a $100k Tesla as much as the next guy, but I'll take my $35k Leaf+lizard battery any day of the week.
 
barsad22 said:
Other reasons?
Lower average daily discharge-recharge cycle. There is no reason to believe that the average driving distance of Tesla owners is significantly longer than than the average driving distance for a LEAF owner. As a result, because of the 2.5X to 3.5X larger battery the daily discharge-recharge cycles on the cells in the battery are lower. That reduces the impact of cycles on the life of the battery.

Note also that if you have a battery that is twice as large with half the degradation, you still have lost the same amount of kWh of storage capacity. For instance, Tony's 10% capacity loss after 53,000 miles equates to the amount of capacity lost by a LEAF showing 20% capacity loss like the OP is seeing: In both cases, nearly 5 kWh of battery capacity has been lost.

(Yes, I fully understand that from the owner's perspective, the opposite is true: A smaller loss in a vehicle with lower range is felt more fully. The point is that just as much battery is "lost" or "wasted". Another way to put this is that there is an incentive to not put more battery in an EV than is needed to fulfill the mission.)

The very good news is that Li-Ion battery technology marches on and the newest batteries have more capacity AND do not lose their capacity as much as previous generations did.
 
Stanton said:
You can't ignore the fact that a Tesla costs 2-3x that of a Leaf! Nissan made many design choices (discussed ad nauseum on this Forum) to make the Leaf available "to the masses".
Hi Stanton -
I am ignoring that fact because in 2017 Teslas aren't going to cost 100K. The Model 3 is supposed to be 35-40K (which is what I paid for my Leaf in 2011), so that's why I'm asking about batteries now. When I am trying to decide between a Model 3 and a Leaf Gen 2 (or a Bolt) 2 years from now, I'd like to have some hard numbers about degradation and battery quality. Actually I heard Leaf Gen 2 won't happen until 2018, so that might make the choice easier.
So I've heard that most degradation occurs during recharge when the battery is at high temps for long periods of time. Does Teala's system cool during recharging or only during driving?
All good points people have made here. It's nice that everyone who bought 2013s and higher are having better numbers, but Nissan has done little for those of us who were early supporters. Though I do feel positive about the major improvements in battery tech the last few years, I do not feel positive about Nissan doing nearly nothing to support those of us with less than 80% of our original range (and rubbing it in by selling the current improved Leafs for $10K-$15K less than the 2011 price).
Yes, I know, you asked for it, Mr. Early Adopter. :)
JG
 
barsad22 said:
I am ignoring that fact because in 2017 Teslas aren't going to cost 100K. The Model 3 is supposed to be 35-40K (which is what I paid for my Leaf in 2011), so that's why I'm asking about batteries now.
Asking now is good.
And historically, basing a comparison on the original Leaf and Tesla is a good comparison, as they perform very differently.
That said, you can't ignore cost if you accept the fact that an active TMS is part of the issue with the Leaf.
The lack of an active TMS affected the price, and could continue to....

So, given that and looking forward, you want to extrapolate and compare the Leaf 2.0 to the Model 3.
Fair enough..
I (this is MY swag here...) expect the Model 3 to have a range of 250+ miles. I expect it to cost closer to $40k. I expect it to be released in '18. I expect it to have an active TMS.
I expect the Leaf 2.0 to have a range of 170 miles or so. I expect it to cost closer to $30k. I expect it to be released before the Model 3. I expect it to not have an active TMS.

I believe Nissan is thinking (true? too early to tell) that their new battery chemistry (Lizard pack and beyond) will be resilient enough to not need an active TMS.

I know lots of people expect the Model 3 to come out sooner with greater range (I agree with that one) and at a similar price point.
I wish Tesla luck and that would be awesome.. But even if I were a betting man (I'm not), i wouldn't bet on it..

That said, if Tesla can release the Model 3 around the same time as the Leaf 2.0 with a greater range and within $5k, I think Nissan will be in trouble. ;-)

desiv
 
Yes, Tesla battery management system will kick in to cool, or heat the battery pack while charging, or SuperChargering.
 
Even if the Model 3 was as much as $10K more, I'd still buy it over the Leaf, what with everything else that Tesla brings to the party that Nissan does not.

desiv said:
That said, if Tesla can release the Model 3 around the same time as the Leaf 2.0 with a greater range and within $5k, I think Nissan will be in trouble. ;-)
 
anyone see the recent article about Tesla degradation? I was in the middle of something so only skimmed it but looks like degradation was a bit more than expected and seems to not be an uncommon thing. I did a quick search and found other Tesla owners seeing range loss as well so what you were told was a bit a of stretch it seems but ya TMS helps but it also is a vampire drain that large packs can afford. smaller packs not so much.

fact of the matter; if EVs were really that easy, there would be more of them out there. Nissan did not do nearly as bad a job as everyone seems to think they did
 
DaveinOlyWA said:
anyone see the recent article about Tesla degradation? I was in the middle of something so only skimmed it but looks like degradation was a bit more than expected and seems to not be an uncommon thing. I did a quick search and found other Tesla owners seeing range loss as well so what you were told was a bit a of stretch it seems but ya TMS helps but it also is a vampire drain that large packs can afford. smaller packs not so much.

Tesla degradation on the roadster is one thing

Tesla degradation on a Model S85 with A pack is another

Tesla degradation on a Model S85 with B pack or early S60 with A or B pack is yet another

Tesla degradation on a Model S85 with D or E pack or S70 or S90 is yet another

Tesla has full on temperature control even when the car is off. Any degradation issue they found in the early packs they fixed every time they did a revision to the battery packs.

Model S owners don't have the equivalent of Leafspy and find that the dash range amounts change from software revision to software revision so they can't be sure they even have any degradation unless they take the car into Tesla to check for them. To add to the fun of comparing they have two styles on the GOM, rated range and ideal range. One is less subject to change by software than the other but they do change.

I don't know that anyone on Teslamotorsclub.com (the equivalent to mynissanleaf.com) has any solid data about degradation of a modern Tesla pack. There were those that had noticeable issues with Roadster and early S85 packs but the majority of the people with anything noticeable got a pack replacement and even then didn't have hard data like Leaf owners have.

If anything gets too far out of whack Telsa gives you a loaner pack and fixes (refurbishes) your old pack then gives it back to you (as in swapping packs as many times as needed until you have a properly working pack that you own again).

All in all, I'd trust Tesla 100 times more than Nissan on being reasonable about replacing a faulty pack and/or selling me a capacity upgrade.

Nissan might catch up a notch if they offer the 30kWh or higher capacity packs to 2011-2015 Leafs as a purchasable upgrade option but even then they would be leaps and bounds behind the battery pack support Tesla gives.
 
Tesla's TMS philosophy is all about safety, not longevity, that is why they would brick (permanently destroy) a Roadster battery pack before allowing the TMS to cease function. Any longevity benefits were distantly secondary.
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look at the cooling targets 40c passive and 55c active!
that Tesla's active cooling target would cook a Nissan LEAF battery.

as it stands, both Tesla and Nissan seem to have improved longevity considerably, Moore's law may not have applied to battery capacity, but there has been a Moore's law type improvement with longevity. It was however something that is not clearly documented or explained by the manufacturers.

its possible that Tesla 90kWh has lower longevity than 85kWh (or more precisely, an earlier knee for degradation, but if that occurs after 500,000km does it matter ?) real world wear is different to modeled wear.
 
As an example of Model S real-world degradation, here's an except from a post today by a member on TMC:

55K+ miles on my Model S S85 and I've made the Nixa, MO to St. Louis round trip at least 10 times over the past 2 1/2 years. But as battery degradation sets in it has become apparent that it is impractical to make that trip in the Model S any more until they install a Supercharger between Springfield, MO and St. Louis on I-44. Why this part of the country (and especially Arkansas) are being so completely neglected is beyond me. I made the trip North (the easier run due to tail winds and a slight elevation drop) with a 45+ minute stop at the Greenstay HPWC (about 24 MPH charge rate) in St. James with about 22 miles of range left. Coming home I didn't have time for a stop longer than about 20-30 minutes and, despite driving 60-65MPH and drafting big rigs for a short time AND raising the AC temp to 78 I arrived home with just 5 miles of range.
Nixa-STL is about 230 miles. That there needs to be an SC in Rolla, MO is obvious.
 
TomT said:
Even if the Model 3 was as much as $10K more, I'd still buy it over the Leaf, what with everything else that Tesla brings to the party that Nissan does not.
While I am inclined to agree with you (long distance travel via Supercharging is worth a lot to me) Nissan has some advantages in areas other than batteries. Teslas have had a lot of drive unit replacements, as many as three per car, as well as needing a lot of wheel alignments, to name just a couple of common problems. How many motor or drivetrain repairs have we heard about on the LEAF? Other than battery degradation the LEAF, especially 2011 and 2012 MY, has been been pretty solid and reliable. That certainly has been my experience. That does not seem to be the case with the Model S, not even close.

Also, Tesla service centers are few and far between. That's not an issue for those in cities that happen to have one nearby (although the waits for service can be weeks or months in some places). But for those of us who don't live in areas with a Tesla service center, getting repairs or routine service can be difficult. That was going to be taken care of by the Ranger program (where Tesla sends out a technician or picks up the car) but they now charge very high fees for that service. By contrast, LEAF-certified Nissan dealers are considerably more common. The lack of Tesla service centers could be a significant problem if the Model 3 sells in the numbers that Tesla is hoping for (500k/year by 2020). Especially if the drive unit issues continue. (Why can Nissan build a reliable motor but Tesla can't? Might it be best if Tesla just gave up on the induction motor?)

Battery issues aren't everything. If Nissan does get a relatively robust battery and long range, they could become competitive for those who don't plan to use the car for long road trips.
 
My 2012 Leaf has dropped to 51ah/211Gids (was 66ah/269 when new) and has NO CHAdeMO and only 22k miles.

My 2014 Rav4 has 26,800 miles and now shows 148 on the GOM after a reset. It was 153 miles new with 17 miles at the dealership on the GOM (it's how it calculates range).

And I've been doing ALOT of DCQC'ing on it too! So it's safe to say Tesla has their act together.
 
dgpcolorado said:
Teslas have had a lot of drive unit replacements, as many as three per car, as well as needing a lot of wheel alignments, to name just a couple of common problems. .

The wheel alignment and drive unit replacements are the same issue (Tesla pushing things to the edge of design).

They aren't replacing tons of drive units for failures (some did fail, but others were preemptive). They are replacing most of them for structural design changes to improve the cars performance and/or to get rid of noises that don't affect actual reliability or performance.

The alignments issue is primarily because Tesla is running high performance with overly large diameter rims for looks. 3 classes of OEM rims / tire layouts on the Model S

19"
21"
21" with larger width rear tires (staggered layout)

The larger tires are more susceptible to excess wear on the inside edge due to the alignment choices that Tesla made for performance.

The extra large rear tires wear even faster and make alignment choices worse because you can't rotate the tires front to back.

You can bet your bottom dollar they won't be pushing the Model 3 to those extremes. They'll choose a more sensible alignment, rim, tire setup. It'll also help that the car will weight less.

Maybe they do 17" rims standard and 18" as an optional? Maybe they do something else. Whatever they do I'm not worried about drive unit reliability as a concept. They have that under an unlimited mile warranty that is quite consumer friendly.

http://www.teslamotors.com/blog/infinite-mile-warranty

The Tesla Model S drive unit warranty has been increased to match that of the battery pack. That means the 85 kWh Model S, our most popular model by far, now has an 8 year, infinite mile warranty on both the battery pack and drive unit. There is also no limit on the number of owners during the warranty period.

Moreover, the warranty extension will apply retroactively to all Model S vehicles ever produced. In hindsight, this should have been our policy from the beginning of the Model S program. If we truly believe that electric motors are fundamentally more reliable than gasoline engines, with far fewer moving parts and no oily residue or combustion byproducts to gum up the works, then our warranty policy should reflect that.

To investors in Tesla, I must acknowledge that this will have a moderately negative effect on Tesla earnings in the short term, as our warranty reserves will necessarily have to increase above current levels. This is amplified by the fact that we are doing so retroactively, not just for new customers. However, by doing the right thing for Tesla vehicle owners at this early stage of our company, I am confident that it will work out well in the long term.

– Elon
 
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