Tesla's Batteries are holding up well

[myleaf]

Tesla (TSLA) Batteries Found to Outperform Internal 5-Year Projections
2:47 PM ET, 07/15/2013 - Street Insider

Despite the Model S grabbing most of the attention for Tesla Motors (Nasdaq: TSLA), there's still some life left in the Roadster. Actually, event more than even the company expects, at least in the battery compartment.

Plug In America recently released a report highlighting the stellar performance of Tesla Roadster batteries. From a release over the weekend: Battery packs in Tesla Motors' Roadster electric cars will retain an average of 80- to 85-percent of capacity after 100,000 miles driven, according to a study published ... by Plug In America ... The finding, released here at the Teslive Tesla users conference, bests initial projections set by Tesla Motors in 2006 which suggested a 70-percent capacity retention after five years and 50,000 miles driven, said Tom Saxton, Plug In America's chief science officer.

Continuing: Plug In America has also launched battery-pack performance surveys of the 1997-2003 Toyota RAV4-EV and the new Tesla Model S. The RAV4-EV survey will document the 10-year experience of owners of these early electric vehicles ... It is premature to glean much about battery capacity for the Model S, which became available in mid-2012, but this research has already shown that survey participants are driving an average of more than 16,000 miles per year, well above the national average of 13,500 miles for conventional vehicles, Saxton reported.

 

[Weatherman]

What I thought was a real stretch of logic was another article where the author was arguing that the success of the Tesla battery proves that the Nissan LEAF battery is long-lasting, too.

As someone who has lost around 15% of capacity in a less than a year and less than 10,000 miles, I had to laugh.

 

[scottf200]

What I thought was a real stretch of logic was another article where the author was arguing that the success of the Tesla battery proves that the Nissan LEAF battery is long-lasting, too.

Title: Tesla Roadster Battery Study Proves That Nissan LEAF Battery Is Long Lasting Too
1 hour ago by Mark Kane
http://insideevs.com/tesla-roadster-battery-study-proves-that-nissan-leaf-battery-is-long-lasting-too/" onclick="window.open(this.href);return false;

 

[Weatherman]

What I thought was a real stretch of logic was another article where the author was arguing that the success of the Tesla battery proves that the Nissan LEAF battery is long-lasting, too.

Title: Tesla Roadster Battery Study Proves That Nissan LEAF Battery Is Long Lasting Too
1 hour ago by Mark Kane
http://insideevs.com/tesla-roadster-battery-study-proves-that-nissan-leaf-battery-is-long-lasting-too/" onclick="window.open(this.href);return false;

Here's the key paragraph from that article:

"For comparison we will use Nissan LEAF battery pack that, as you know, was criticized by Tesla CEO Elon Musk for its lack of an active thermal management system . This is big drawback and, in hot climates, LEAFs have problems with capacity fade. But the cells alone, in normal conditions or with thermal management, should be twice as durable those used by Tesla."

Normal for whom? Astoria, OR?

And, of course the LEAF battery doesn't have thermal management and Nissan has no intention of ever putting one in.

 

[TomT]

Nissan wildest dream is that the Leaf battery would be even remotely as long lasting as the Tesla battery! We all know that is not even remotely true and until there is either a dramatic change in chemistry and/or a TMS added, it never WILL be true. I wonder if Nissan would still leave out TMS if they could do it all over again...

What I thought was a real stretch of logic was another article where the author was arguing that the success of the Tesla battery proves that the Nissan LEAF battery is long-lasting, too.

 

[KJD]

What I thought was a real stretch of logic was another article where the author was arguing that the success of the Tesla battery proves that the Nissan LEAF battery is long-lasting, too.

Title: Tesla Roadster Battery Study Proves That Nissan LEAF Battery Is Long Lasting Too
1 hour ago by Mark Kane
http://insideevs.com/tesla-roadster-battery-study-proves-that-nissan-leaf-battery-is-long-lasting-too/" onclick="window.open(this.href);return false;

I think that title used by Mark Kane is misleading, maybe even downright wrong. Go back to the original article by Tom Saxton and see what you think.

http://www.pluginamerica.org/surveys/batteries/tesla-roadster/PIA-Roadster-Battery-Study.pdf" onclick="window.open(this.href);return false;

http://www.pluginamerica.org/press-release/plug-america-research-shows-tesla-roadster-battery-performance-bests-tesla-motors%E2%80%99-own" onclick="window.open(this.href);return false;

 

[WetEV]

Nissan wildest dream is that the Leaf battery would be even remotely as long lasting as the Tesla battery! We all know that is not even remotely true and until there is either a dramatic change in chemistry and/or a TMS added, it never WILL be true. I wonder if Nissan would still leave out TMS if they could do it all over again...

Not everyone lives in hot places.

I doubt if a TMS would change my battery life significantly. So far this year I've seen 6 TBs twice. Once since I could monitor temperatures with Leaf Logger. Peak battery temperature was 82F. Was 75F the next morning. Most of the past month has been under 75F, below 70F range seems most common. And it is summer, and a warmer summer than last year. Battery temperature was 70F this morning, and with the highest temperature of the year so far forecast for today, might have another 6TB by the time I get home.

 

[smkettner]

Not everyone lives in hot places.

Correct and I am still losing 10% per year according to the Nissan gauge.

 

[TomT]

You don't need to live in "hot places" to benefit from a TMS... If you QC, you benefit. If it is cold where you live, you benefit. And experience is showing that what is rather temperate to everything else is still hot to the Leaf battery, so they would benefit...

Not everyone lives in hot places.

 

[WetEV]

You don't need to live in "hot places" to benefit from a TMS... If you QC, you benefit. If it is cold where you live, you benefit. And experience is showing that what is rather temperate to everything else is still hot to the Leaf battery, so they would benefit...

I've QCed about 10 times. Multiple QCs in a day will get 6TBs, done that, as will a QC when the battery is already warm. Half never exceeded 5 TB. One QC turned on 6TB, but was 5TB by the time I got home.

Cold, if you need the range, but doesn't get cold enough in Puget Sound to bother me.

Still don't see much benefit from a TMS to me. Still don't see how the TMS would have turned on for more than 24 hours total in the past year.

 

[Sublime]

Nissan wildest dream is that the Leaf battery would be even remotely as long lasting as the Tesla battery!

Comparing a battery pack that sees 2x - 3x the cycles for the same mileage isn't really a fair comparison.

 

[TomT]

Mileage and time is the only fair comparison. The fact that Tesla provides a larger pack is Nissan's problem, not Tesla's...
But even with the same size pack, I'm certain that Tesla would still whip Nissan's butt soundly.

Nissan wildest dream is that the Leaf battery would be even remotely as long lasting as the Tesla battery!

Comparing a battery pack that sees 2x - 3x the cycles for the same mileage isn't really a fair comparison.

 

[DaveEV]

Personally, I think that it is quite a stretch to say the following two things:

"18.9% of the cars have had either a single sheet or the entire pack replaced."
"Tesla Roadster batteries are holding up well."

Excluding outright failure, yes, the packs have a very good rate of capacity loss on average and surprisingly (at least for LEAF owners) vehicle miles are a stronger indicator of battery capacity than calendar age.

Personally, I had expected Tesla Roadster levels rates of capacity loss when I bought my LEAF - after all, AESC's automobile specific chemistry and my mild climate surely must hold up at least as well as the laptop cells used in the Roadster. After 2 years and 20,000 miles I expected to be down less than 5% in capacity. Unfortunately it's at least twice that (currently at 56.7 Ah, 200 GIDs @80%) even in San Diego. I don't even think that BMS would necessarily help all that much given that my pack appears to mostly sit only between 80-85F so far this summer.

 

[Sublime]

Mileage and time is the only fair comparison. The fact that Tesla provides a larger pack is Nissan's problem, not Tesla's...
But even with the same size pack, I'm certain that Tesla would still whip Nissan's butt soundly.

You're either comparing 2 vehicles who's price isn't in the same ballpark or 2 vehicles who's battery configuration isn't in the same ballpark. Depth of discharge is an enormous factor on battery life. The stress on the pack for a LEAF with 30k miles is equal to a roadster with at least 65k, when you consider the non-linear damage charging and driving at the SOC extents it's probably even more than that.

 

[TomT]

Based on what has been observed in hot (and even more temperate) climates, it seems clear that degradation on the Leaf is much more temperature driven than by anything else. Thus, both the Leaf and Tesla are on an even playing field regardless of price or cycles... And the Leaf looses...

Mileage and time is the only fair comparison. The fact that Tesla provides a larger pack is Nissan's problem, not Tesla's...
But even with the same size pack, I'm certain that Tesla would still whip Nissan's butt soundly.

You're either comparing 2 vehicles who's price isn't in the same ballpark or 2 vehicles who's battery configuration isn't in the same ballpark. Depth of discharge is an enormous factor on battery life. The stress on the pack for a LEAF with 30k miles is equal to a roadster with at least 65k, when you consider the non-linear damage charging and driving at the SOC extents it's probably even more than that.

 

[surfingslovak]

Mileage and time is the only fair comparison. The fact that Tesla provides a larger pack is Nissan's problem, not Tesla's...
But even with the same size pack, I'm certain that Tesla would still whip Nissan's butt soundly.

You're either comparing 2 vehicles who's price isn't in the same ballpark or 2 vehicles who's battery configuration isn't in the same ballpark. Depth of discharge is an enormous factor on battery life. The stress on the pack for a LEAF with 30k miles is equal to a roadster with at least 65k, when you consider the non-linear damage charging and driving at the SOC extents it's probably even more than that.

The author of that article conveniently overlooked calendar aging and considered cycling losses only. To be fair, Tom Saxton's study led him onto it. He claims that this is what he saw in the data. I specifically asked about that during his presentation at Teslive, where he unveiled the Roadster battery study. Perhaps calendar aging is minimal, partially thanks to the TMS. It's difficult to say.

What is often misunderstood - lithium oxide chemistries are quite temperature sensitive. Any range loss, especially early in the life of the vehicle, is typically driven by chemical processes that can be effectively mitigated by managing the temperature of the pack.

We saw a LEAF last year, which lost about 7% of battery capacity by just baking on dealer parking lots. It had 160 miles on the odometer at the time of purchase. With larger packs, like the 85 kWh one the top Model S trim uses, the effects of mileage are even less pronounced. It takes only about 50 full cycles to achieve annual mileage of 12K.

 

[jkirkebo]

Based on what has been observed in hot (and even more temperate) climates, it seems clear that degradation on the Leaf is much more temperature driven than by anything else. Thus, both the Leaf and Tesla are on an even playing field regardless of price or cycles... And the Leaf looses...

Temperature seems to be the key, yes. My Leaf is 1 year 9 months old and I have done lots of QC (up to 4 one day which got me to 8TB). But our climate is pretty cold (Norway) and I never get above 5TB without QCing. In winter it is usually somewhere between 1TB and 3TB.

We haven't seen any temperatures above 75 F so far this summer, most days are 65-70.

My Leaf still charges to 278-279 GIDs and have the same range as new.

 

[LEAFer]

^^^ How many miles (km) ?

 

[jkirkebo]

^^^ How many miles (km) ?

A little under 17,000 miles now.

 

[mkjayakumar]

Which is why unless we see statistics on Model S and Roadsters that lived in the AZ, TX regions for two years or more, with a minimum of 25K miles in it, it is meaningless to declare victory.

Others might be fooled, but Leaf owners need hard data that they can relate to.