TMC Connect 2014 - Save the Date - July 18-20

[CarlK]

Several conference attendees have asked about getting a copy of my slides from the conference. They are now available here:

Model S Battery Pack Longevity

Model S Performance (all but the first slide appear in the Battery Longevity slides)

They are just the slides with no additional commentary, so they probably won't make a lot of sense unless you attended the talks. I plan to update the charts with the data that has been added to the Model S survey since I finalized the presentations for the show (including Dante's 91,500-mile report), add a chart comparing "A" batteries to later versions, and write a paper to explain it all. That's at least a few weeks out, but I wanted to make the slides available for TMC Connect attendees right away.

Tom, Thanks for the great data. However I'm still not sure if I understand the definition of pack cycle correctly. Do you consider two cycles from 80% -> 30% -> 80% the same as one cycle from 100% -> 0% -> 100% and both counts as one cycle? What are the bases of this assumption?

 

[ecarfan]

I do realize that once they decided to pursue their own path, they ultimately made the SCs more capable than other chargers, and these are all moot points now given how well the SCs have worked out. Both the industry and Tesla are each now in a different place, and I don't think there is any legitimate question of the success of the SCs. But under similar circumstances I'd raise similar questions- so while my current view of SCs may be different, I didn't retroactively change that original position when asked.

I applaud your clear and extremely well-reasoned answer! I appreciate it when someone takes the time to craft such a thoughtful and rational post. Thank you.

 

[ecarfan]

I think people tend to underestimate the aesthetics of the connector...
I heard comments along the same line when I showed her the first CHAdeMO charging station we saw in the wild. The connector is big (subconscious: DANGER), and yes - it's round, so there's not instant alignment. In fact, when you need videos to demonstrate to consumers how to properly connect to a quick-charger without breaking the charger, you're probably Doing It Wrong(tm). (How To Use a Yazaki CHAdeMO Connector - YouTube)

I offer that Tesla was smart here to reject the existing connectors in favor of a better design.

I have never used a CHAdeMO charger, I have only used Tesla cables. I watched the video. It left me speechless. The CHAdeMO design is shockingly bad. It is excessively complicated, not intuitive, and yes, ugly. In contrast, the Tesla cable is simple, attractive, and it's use is intuitive. No training required.

Tesla did the right thing in designing their own cable to a much higher standard. In a couple of years when Superchargers are widespread and ubiquitous in North America, Western Europe, and China (with build outs in other regions well underway) it will be obvious that all other EV charging systems are archaic.

 

[tomsax]

Tom, Thanks for the great data. However I'm still not sure if I understand the definition of pack cycle correctly. Do you consider two cycles from 80% -> 30% -> 80% the same as one cycle from 100% -> 0% -> 100% and both counts as one cycle? What are the bases of this assumption?

In order to compare Model S (60 kWh and 85 kWh), Roadster and LEAF, I divided estimated lifetime kWh by the size of each vehicle's battery pack. I'm certainly not saying that 2 50% middle SOC cycles are exactly the same as a full 100% cycle, but it's a good first order approximation. It may not be perfect, but it's much better than comparing vehicles by miles or kWh.

In order to do a more sophisticated model, I'd need full live telemetry from each vehicle, which I don't have.

 

[pete8314]

I have never used a CHAdeMO charger, I have only used Tesla cables. I watched the video. It left me speechless. The CHAdeMO design is shockingly bad. It is excessively complicated, not intuitive, and yes, ugly. In contrast, the Tesla cable is simple, attractive, and it's use is intuitive. No training required.

Tesla did the right thing in designing their own cable to a much higher standard. In a couple of years when Superchargers are widespread and ubiquitous in North America, Western Europe, and China (with build outs in other regions well underway) it will be obvious that all other EV charging systems are archaic.

Agreed. There's been so many bad consumer-facing 'standards' in the past that are so unintuitive, presumably designed by committee. Who doesn't enjoy blindly trying to plug an HDMI cable in behind a TV? Those in Europe will remember the monstrosity that was the SCART plug. There's USB where (in theory) you stand a 50/50 chance of getting it right first time, but it never seems to work out that well. The list is endless.

I've heard various people say in the past that certain things in the Model S are there because 'what Elon wants, Elon gets' (the door handles, for example). It takes a certain kind of character to do that (Steve Jobs being another example) and it's not always right, by any means, but on average the success rate is good. My kids figured out how to plug in the S on the first try. I wouldn't trust them not to ding the car half a dozen times with a CHAdeMO plug before giving up. Dreadful design, at least from the end-user point of view.

 

[CarlK]

In order to compare Model S (60 kWh and 85 kWh), Roadster and LEAF, I divided estimated lifetime kWh by the size of each vehicle's battery pack. I'm certainly not saying that 2 50% middle SOC cycles are exactly the same as a full 100% cycle, but it's a good first order approximation. It may not be perfect, but it's much better than comparing vehicles by miles or kWh.

In order to do a more sophisticated model, I'd need full live telemetry from each vehicle, which I don't have.

Thanks. I think it makes good sense to compare cars with different battery capacities that way. I wish you have made it clear that's what you meant. Maybe you did just that in your presentation but there are people who looked at your slide and intepreted it as cycling the battery from 0% to 100% has no bearing on battery life. It's not what Tesla has been saying.

 

[tomsax]

Thanks. I think it makes good sense to compare cars with different battery capacities that way. I wish you have made it clear that's what you meant. Maybe you did just that in your presentation but there are people who looked at your slide and intepreted it as cycling the battery from 0% to 100% has no bearing on battery life. It's not what Tesla has been saying.

As I said in my post, those slides are for people who attended my talks and wanted to see the slides in more detail. They are not intended to be a stand-alone substitute for attending the talks. I will write up a paper that explains everything, but that is going to take at least a couple of weeks and I didn't want to deny conference attendees access to the slides until then.

 

[spleen]

As I said in my post, those slides are for people who attended my talks and wanted to see the slides in more detail. They are not intended to be a stand-alone substitute for attending the talks. I will write up a paper that explains everything, but that is going to take at least a couple of weeks and I didn't want to deny conference attendees access to the slides until then.

It's greatly appreciated, Tom. I enjoyed your talk.

 

[DaveT]

Does anybody know when the videos for TMC Connect talks will be posted online?

 

[lorih]

Doug is still traveling, so they won't be posted at least until he gets back.

 

[DaveT]

Doug is still traveling, so they won't be posted at least until he gets back.

Thanks, Lori.