Continue reading the ABG interview with Martin Eberhard after the jump to learn more about the Roadster, batteries and WhiteStar.
ABG: So you did this based on the fact that you wanted an EV but couldn't find anything suitable that was on the market. How did you come to decide to build a car like the Tesla Roadster as your starting point?
ME: Well, I guess when I looked at so many electric cars are out there, it seemed to be that they were built by people who considering driving a necessary evil. You really shouldn't drive. You should walk or take a bike or ride the bus. And if you must drive then a little glorified golf cart would be fine. I like cars. I've owned a variety of sports cars and I enjoy driving, and I think that I'm typical of a lot of Americans that we actually do like our cars. And of course we do feel guilty about how much oil is consumed and the dependence on oil, the CO2 production, global warming and all that. So we still actually like our cars and when I thought about this– when we started building a car it was designed for people who like to drive. We'd have a lot more success than a car that wasn't designed that way and persuading people that cars were bad.
ABG: Well given the track record of many of the small companies that have tried to start up building EVs, which hasn't been particularly successful so far, it seems like that's a pretty good approach to take. Myself having been a longtime fan of Lotus, when I first saw the Roadster it was immediately obvious that it was based on the Elise or derived from the Elise. I was pretty excited to see what you guys were doing and when I saw the performance specs it was pretty impressive. How did you come to decide to use the Elise as a base and give us a little background on the technology in what you're doing.
ME: Well, so we set out to build a high performance sports car and we looked at who we could partner with to put that car together. Lotus was a company that made sense for us because of the size of the cars that they made and the fact that their factory has built cars for other companies already. They're used to doing that. I'd like to clarify something, we do have some carryover equipment on the car from the Elise. We have the same airbag system. We have a similar crash protection system. But it isn't so much based on the Elise. There was maybe 10 percent common parts to it in our cars. The windscreen, the airbag system, some of the surround, some of the rubber seals, that kind of thing. The chassis of the car is not a Lotus chassis and the body is clearly different than the Lotus body. There are no common parts.
ABG: Well, I guess when I first saw it from, just from the shape of the windshield and the general proportions of the car you could see some, some heritage there of the Elise. But yeah, you're right, it is a different car. How are things progressing with the development of the Tesla Roadster and are you guys still on track for a launch this year?
ME: Things are going quite well. I mean, you know it's difficult to put on. There's a lot of pieces to it. You've probably heard the rumors that we changed to a different supplier for our transmission and went into a redesign on that and that's definitely the long pole in the tent right now. But even that problem is under control and things are going well. We are on schedule to ship cars this year.
ABG: Okay. With the testing, obviously you don't need to do emissions and fuel economy testing for this thing. But what what sorts of other things are you doing as far as testing and particularly durability testing? What sort of program do you have for that?
ME: Basically the testing falls into two classes. There's safety testing and the durability testing. The safety testing is the standard gamut of standard motor vehicle safety standard testing and that involves smashing quite a few vehicles because the requirements are for low speed frontal crash tests, high speed crash tests, offset and deformable front crash tests, side intrusion tests, low speed and high speed rear crash tests and roof crush tests. So that's really a large number of tests have to be done. The way that this testing is done is we do testing to learn some things and then they'll redesign whatever needs to be redesigned and then you get approval. So that usually means a full set of testing once and then a full set of testing again with whatever changes went into it. The same thing goes with durability testing there's two classes of durability testing we do. We do a super accelerated test that's called the Belgian Pavẻ test, which basically drives the car over a very harsh cobblestone road at high speed and will take pretty much any car to destruction in about, in about 4- or 5,000 miles. That's designed to catch early failures as quickly as you can in the program. We finished that test and actually did quite well on it, had a very small number of failures. We had one bracket break on a front suspension component that we redesigned. And then parallel with that is a much longer durability test. It's about 50,000 miles on a calibrated durability track that's designed to simulate a much larger number of miles of actual driving, and that's ongoing still today. We're running three shifts a day six hours a day of that car driving on the track. And that's going well also. We've learned a few things; things that needed some adjustment and we'll do all those tests again with the next round of cars we're building right now that capture everything we've learned.
ABG: From that testing, I think probably the big question that everybody is going to want to ask is; How are the batteries holding up during the testing? Particularly, I've driven cars on the Belgian Pavẻ, so I'm familiar with how severe that is. How is the battery pack holding up, especially given the nature of your battery pack, where you've got I think 6,000 some odd individual cells in there, that are wired together, on the longer term durability testing. How is the performance of the battery over a larger number of miles, how is that holding up?
ME: Oh, the battery pack has been essentially perfect. We've had no trouble at all with the battery packs in the Pavẻ test or in the long-term durability test. You understand that these are not just a pile of batteries that are just chucked in a box. These are mounted in, in a very, very sturdy way with some our patented technology and that works frankly, just great. We had a problem with a bracket on the battery box early on in the testing that mounted to the frame. The bracket wasn't strong enough and we had to increase the strength of the of the bracket. This is the kind of thing that typically gives out during this kind of testing. We've had other kinds of problems. We had on the long-term durability track, one of the pieces is driving through a saltwater bath, which is abusive of a car. And we did have some water getting into one of our cables. So it required us to change the design of the cable and make sure it was simply more waterproof. Those are the kind of things you learn along the way. But the battery system has been one of the most robust parts of the tests so far.
ABG: What about the performance of the battery after 40-50,000 miles? Have you been able to take a look at that? And how's it, holding up?
ME: So far it's holding up just great. Holding up well, somewhat better than the computer models predicted.
ABG: Well, that's great to hear because that's clearly an issue with lithium ion batteries these days. Everybody has had experience with them in consumer electronics devices and they know that over the span of a couple of years they start to lose their ability to hold a charge. And so I think that's other than the mechanical durability of the components of the cell or the battery pack, that's the other big question when dealing with lithium batteries.
ME: Right. There's nothing unique about lithium batteries for Heaven's sake. You have lead acid batteries and nickel metal hydride batteries and nicad batteries, every battery chemistry that's come along. Batteries do degrade with time and with usage. The lithium ion battery is actually better than all of the predecessors for the most part. But the the difference between the Tesla Roadster and let's say, for example, your laptop computer is that your laptop computer was designed to last a short number of years. I mean, Microsoft just conspired to make sure that your laptop is obsolete in five years and so if the battery pack poops out in five years that's okay, that's fine. So there's no attempt to keep the battery pack cool. There's no attempt to optimize the charging of the battery pack just so long as the battery lasts a couple of years is good enough. We have of course a different approach with the Roadster as you've seen, we do liquid coolant in the battery packs to keep the battery packs at their optimal temperatures throughout their lives. and similarly we have a much, much more gentle charging and discharging algorithm on the batteries to optimize their life. It's just a matter of design.
ABG: So you've got a cooling system for the battery pack. Does that mean that it also warms the battery pack? Because that's another issue with lithium batteries, when they get cold they obviously don't perform as well either. So are you heating it as well in cold weather?
ME: So what happens with lithium ion batteries and mostly any other batteries when they get cold is they have a somewhat reduced power output. We don't under normal circumstances heat the battery pack because if you're driving at minus 20, your 0 to 60 time instead of being 4 seconds might be 5½ seconds. That's probably okay. Especially considering that you're probably on ice.
ABG: Odds are if you are at that temperature then you probably don't want to be accelerating that fast anyway.
ME: Yeah, you can't. And in fact if you look a little bit harder what you find is that the way that reduced performance manifests itself in the batteries is by increased internal resistance of the battery. So when the battery is cold it will have higher internal resistance. And what that means is that as you use the battery it will self-heat. That resistance in the battery produces heat in the battery and actually warms itself. With use it'll warm right up anyways. But it actually doesn't matter. If you come to our web site and see there's several videos of our cars being tested up in Sweden on a frozen lake in the Arctic Circle. It was minus 30. Our car runs just fine.
ABG: We posted those up on our site as well, and it does look like it's performing well.
ME: And by the way, that driver is a better driver than I. Yeah, it was, it was common place for people to do tuning of mainly ABS and traction control, that's what we were doing. Besides we're just getting an opportunity to really run the car hard in a cold climate. Those are the specific tests that were done. We were out there working with our ABS manufacturer side by side and getting help from them.
ABG: So moving on then, there's obviously been a lot of discussion and rumors in the last couple of months regarding WhiteStar. Can you give us a little background on WhiteStar? What are the goals as far as performance, production volumes, timing and price and so on?
ME: Yes. The larger goal of WhiteStar is to grow Tesla's market and build another model car that appeals to a broader class, a broader group of people. Obviously the first step of that is to seat more people. A two-seater car appeals only to a limited market and obviously price matters as well, which is the reason why we're building our own factories with WhiteStar instead of building them overseas. Then of course across that, you want to carry the Tesla motor's DNA into that car by building a car that is great to drive and beautiful and is still seriously efficient and burns no gasoline. So that's kind of what we started out. We're in the middle of the program, people ask us on our blog and so forth when are we going to post pictures. And the answer is not for a while yet. There's a lot of work to be done.
The transcript of second half of this interview will be coming soon.