AutoblogGreen

Sounds like a lot of fun. But there is one more thing I could ask for from a sports car, which is the ability to put in a reasonable amount of track time on it.

In the SF Bay Area, we're blessed with two world-class tracks nearby. But if you start from home, drive this car to Sears Point or Laguna Seca and do 15 minutes worth of track driving, you'll barely have enough power left to get back home. Even if you park your car at the track and thus start fully charged, you're looking at only a bit over 30 minutes of track time before you have to recharge.

And if you decide to recharge even if you have access to a 220V/60A charger (many homes will have a 30A charger, but a track could easily have a 60A one), it'll only charge 25% per hour, assuming 100% efficiency.

It really hurts this car as a track car, which is a downer given how otherwise tailored for the track it seems. On top of that, I'm told it limits torque (acceleration) as the battery runs down.

But I predict you won't see any of this in the orgasm of press. No, you'll see the car on Top Gear or whatever, lapping like a champ, probably beating a 911, not indicating that it can only do so for a very limited period of time.

The efficiency of the Tesla is amazing in street use, but on the track, you're just expending energy too fast with no hope of recovering any significant amount.

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Yes, range does represent a problem for those who would like to race a Tesla Roadster. (me! me!)

However, if you drove all the way to a race track as you stated, don't you think you'd want to hang around more than just fifteen minutes of racing?
Who goes on a "long" trip (150+ miles) and then doesn't stay for at least a couple of hours. During those couple of hours, you can charge enough to drive plenty. Then on the road, you can charge again while you eat or something.

Yes, with an EV it does take some planning for longer trips. But when you're on a longer trip, it's usually planned out and you usually know where you are going. So, you can make arrangements ahead of time so you know where you can charge andhow long it will take. Yes, it is a problem. However, I think it is a small thing to sacrafice for the sake of a great sports car.

About the post: Great writeup! :)

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I think if you can afford this car and wanted to run it on a track you would just trailer it. If you want to spend a lot of time there just bring one of these. http://www.absak.com/catalog/popup_image.php/pID/861

Great video Sam. Nice road. It was a little hard to get a sense of how fast you were moving but I'm glad you could bring us along.

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The range for track use is a worry. But as Domenick said, if you can afford this car, you can have it trailered. If you don't feel like trailing it, you can have a diesel generator on tow, as seen attached to many EVs on long trips. Yes it looks a little stupid, but you can go out during the morning, have a few runs (after detaching the generator of course), and then go out for lunch, with it charging on the generator. Then you can come back, do a few more runs, and pretty much have a full track day before going home.

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Perfection is the enemy of greatness. No, this car isn't perfect. But it's a game-changer. Once you've seen it, ridden in it, driven in it, all the parts of your body that do the thinking shout, in unison, "want". I sure hope they can translate that down into a more affordable WhiteStar, because it would be great if more people can experience that.

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Pardon me if I'm not thrilled about the prospect of people running external Diesel generators to charge their EVs. Why did we spend all this time even getting road-going Diesel engines down to be somewhat clean so people can use standalone generators to power their cars which don't meet those emissions?

I agree that you'll want to spend some amount of time at the track not in the car, and perhaps you can charge it a little then. But the charge rates are not impressive. Driving 30 mins, then waiting 4 hours while it recharges, then driving 30 mins does not seem like an ideal situation to me.

How am I going to charge on the road while I eat? Do you have 220V/30A outlets available where you eat on the road? I know I don't. And plugging into a regular 110V outlet charges at about 3% per hour. If you go by the 250mi range (or close to it), that means if you plug into 110V while you eat lunch for an hour, you only gain 8 miles of range.

Anyway, I don't want to get off the mark here. I'm not talking about road-going range. The Tesla is not marketed as a long-distance driver, so there's no reason to point out that it isn't one.

My point is more about the track. The track is just so demanding on the batteries that it doesn't seem like it quite fits the bill as a track car.

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@ why not the LS2/LS7?
I just suggested a diesel generator because I was thinking about biodiesel. I know it's not the greatest solution... There are probably (solar generated power in a stand alone battery pack?) less polluting ways of accomplishing this.

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@ why not the LS2/LS7?
Anyone racing at a race track probably isn't that concerned about the environment. That said, the diesel generator seems to be the best bet for people wanting to go farther with the Tesla. I know in EV drag races this is what people do to get a few more runs. Out for lunch you could pull the generator along.
Even in sears/laguna in a 30min session you will really only be running 50miles. Most of the 245 mile range of the tesla would be drained as you travel to the track. The generator (or a trailer if you can afford this) is your best bet to remedy this. As we haven't seen a production version of the Tesla yet, we can't really make the claim that the track time is going to be as taxing as we expect it to be (According to testing by tesla the worst case scenario was a 165 mile range w/ aircon, aggressive start-stop, high speeds, which is similar to what you can expect on a track).
Nonetheless there is no doubt the Tesla isn't the ideal car for the track. As mentioned by ltclloyd you can spend less on a elise/exige and have much less of a hassle. That said, we all know there will be pp putting it on the track, and this is just one proposal of how to remedy some of the problems. The use of EVs in drag racing haven't really been about the environmental benefits, it has been about the torque characteristics of an EV. I think we can say the same about the tesla, the experience will be unique from the experience in an elise/exige, and I suppose this is why people are willing to pay twice the price for it.

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jy:
You can't go by miles. And no, a "worst case" on the street is PEANUTS next to tracking a car. When you run a hot lap, the car is at wide open throttle over 80% of the time, and when it isn't, it's usually at 100% braking. Whenever you brake harder than you can accelerate, the extra braking is coming from real brakes, and cannot be captured with regeneration.

So on each lap, let's say you're running full power 75% of the time, and the rest of the time we'll say it's net zero energy (some acceleration, some regen braking, some maintaining speed).

The Tesla has a 53KWh battery. Let's say it has a 133HP motor. That's a 100Kw motor. So assuming 100% efficiency, you can run it at full power for 32 minutes off a 53KWh battery. 43 minutes lapping would be 32 minutes at full power.

So you can lap for 43 minutes, assuming 100% conversion efficiency.

On a track, you're going to do FAR worse than the street worst case. Just like with a gas car.

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I'm glad that you guys are happy to complain about a car where you don't even bother to think about the critical sub-systems which make all the difference in the scenarios your talking about. Let’s take a look at their site for a bit of an introduction:

"Unfortunately, the adage “your mileage may vary” applies to regen as well. The amount of energy you can recover depends on how and where you drive. From the powertrain point of view it looks pretty good. The energy conversion efficiencies from chemical to electrical (battery), DC current to AC current (inverter), electrical to mechanical (motor), and torque to force (transmission and wheels) are all quite high and work just as efficiently returning energy into the battery. The bigger problem is aerodynamic losses and higher speeds and rolling friction of the tires. These both act to slow the car, but the energy dissipated cannot be recovered. We must also remember that, even though the battery-to-wheel conversion efficiency is pretty good (up to 80% or so), the energy makes a full circle back into the battery and it gets converted twice for a net efficiency of at most 80% * 80% = 64%."

Now, if we look at the physics a motor is almost exactly the same as a generator, expect acting in reverse and batteries give/take current in pretty much the exact same way as well if they are kept at a constant temperature.

Now let’s look at what 'takes away' power:
1. Acceleration: When you accelerate you turn your chemical power into kinetic energy. In an ICE you turn gasoline into mechanical energy threw a contained explosion, in an electric car you use chemical -> electric -> mechanical. Regardless physics tells us that Work = 1/2mv^2.
2. Friction: This takes the form of resistance in a vicious medium (air) and rolling resistance/sliding (tires). Work = kv^2 for air resistance and fd for sliding/rolling.
3. Other features: stereo, climate control, etc. No easy way to measure these, but if you’re really here for the track you don’t need your stereo and you shouldn’t need your climate control in a conversable.


So this is all fine and dandy, but what does this all mean? Quite simply when you break in a normal car all your kinetic energy goes into heat, fun! This is why you have large brakes which at the high end have vents in them, they need to be able to hold as much heat as possible, and get rid of that heat or they will be less functional and thus providing worse performance. In an electric car like this we get about 64% of that energy back. Realistically you would probably get more as most tracks have few high-speed areas but rather have sharp acceleration/braking and high-speed turns. So, that means that we might get 80% of our energy going back to the brakes with a 64% overall efficiency is about 40%. So that 250 mile range adds back another 100 miles, then 40, then 16, then 6.4, then 2.5, etc. So We have just over 414! This is a 60% increase in distance.

So I ask you, if driving 45 minutes per 4.5 hours that bad? If seems to me that driving 10 minutes per hour isn’t so bad, and you could realistically do some good racing. If you spend 30 minutes on the track you have 33% charge left, set it charging and go to watch some other races and have lunch, after 2 hours you get 50% more charge which gives you 80% overall. You can go for 36 minutes. So in just over 5 hours and 6 minutes you can get an hour and 6 minutes of racing. To me, that isn’t so bad and since batteries will be improving over time this is a great ‘first generation’.

Second, track cars get a lot of money, what is to say that they won’t have super-capacitors? They would have about 10 minutes of range (Though much better efficiency and thus maybe more) but would only take 5-15 minutes to recharge (Maybe less if you have a lot of money to invest in your charge times). Then a 66% run time overall isn’t so horrible if you can find short repeating races.

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Small update, 45 minutes was just 'full power' mode, if you count 50% extra time for braking and coasting/very little thoral then you have an hour for driving.

So now, we have 1 hour per charge, so if you drive from full to nothing and charge half more and race you could drive 1 hour, 30 mins over 3 hours 30 minutes. That seems pretty reasonable to me!

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@ "why not LS2/LS7"

"Do you have 220V/30A outlets available where you eat on the road?"

No, not usually. That's why I said you have to plan in advance.

I forgot to ask a very important question for Abuelsamid. The test drives given to Tesla Motors customers were only allowed to drive in second gear.

Was the car driven in first or second gear?

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No Hello Moto. Regen braking is near useless on the track. It's simple, the motor in the car cannot generate any more electrical power out from mechanical power in than it can generate mechanical power out from electrical power in.

In practical terms, than means if you decelerate at a rate higher than you can accelerate, the excess deceleration beyond the equivalent acceleration rate is coming from the brakes. And energy put into the brakes is lost, never to be recovered.

Well, on the track, you are at full throttle or full braking almost all the time. And the full braking is much stronger than full throttle. Can your car accelerate to 60mph in 130 feet? No, but it can stop from 60 in 130 feet.

On the track, you get almost none of your energy back because of the braking characteristics. The energy recovered I can pretty safely say will all be eaten up by the fact that I don't take any energy wastage (less than 100% efficiency) into account in my calculations.

I'm not sure how you tie races into track time. Most track days are not races. You could watch other people practice I suppose.

66 minutes of racing in 4 hours (not counting transport time and BTW, you have to trailer your car to get even this much) doesn't seem very good to me. It's far worse than comparable track cars, that's for sure. And you say this will improve as batteries improve. It isn't going to improve much, as the problem (at this time) isn't batteries. The major limitation is the rate of charge (60A@240V due to the charging source), not the batteries. Perhaps they'll work on a 440V charger? GM promised one for the EV1, but I don't believe they delivered it. A 440V charger and of course installation of 440V supplies to the pits would make a difference. If the Tesla cannot accept 440V input, and the power has to be converted to 120A@240V at the charger, the cable set for charging the car will start to become very unwieldy.

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If you want to drive around a track at high speed for long periods of time the Tesla is not the right tool for the job.

With the current state of battery technology, it's probably not possible to make a good electric track car. There's nothing wrong with that.

A hammer makes a lousy wrench, but so what, that's why we have different tools, and different vehicles.

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With the current state of battery technology, it's probably not possible to make a good electric track car.

I guess you must have missed all the news about all the fast-charge capable batteries ?

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As far as racing on the track - I'm going to chime in with a big, giant, "who cares".

Sorry, but most people just don't race at track. Even in the demographic that can afford the Tesla, most people just don't race at the track. Nor do they race on the street. They just _drive_.

The roadster in question isn't designed for it, and we may as well talk about going off-road in the thing.

That said - if the battery pack was modular, and you could switch packs as easily as filling a gas tank - then we're talking about a track car.

For now, the roadster is maybe the easier piece of engineering than the family sedan (small sports cars are already lightweight/low drag), and its sexy enough to generate interest and raise some money for Tesla to keep producing.

And finally, don't you race against cars of similar specs? I've never been to a day of Ferrari flogging at a track, but isn't the idea to test driver prowess as well as engineering skill? Seems to me with chargers installed at the track, you could run a bunch of roadsters in heats and leave plenty of time for the gassers to run in-between while they charge up.

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There is an awesome version of the tesla that is made for the track and costs 1/2 as much and no limitations. It's called a lotus elise.

now with that being said. The last Event I instructed at had 4 run groups. which cycled 3 times in an 8 hour day. which affords the driver 2.6 hours between what is typically 15 or 20 min sessions. and yes almost EVERY track has motorhome 60 amp hookups. so you MIGHT be able to do it.

of course we will not get into the environ-mental effect of burning through 1/2 a set of tires on a track weekend.

If I had the money... I'd take the Elise to the track. invest the remaining 60,000 throwing off 8% interest which should allow me to afford 10 additional track days a year with no effect on principal. Of course my car is a sentra that laps Sebring Long course on par with most 911's (2:40's) so do the math.

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Kert:
It's not a battery problem. Please read my post again.

Even conventional LIons can be charged to 80% in one hour. This vehicle is only charging 25% in one hour. This is because of the difficulty of getting enough power out of the wall into it fast enough, not because the batteries can't take it faster.

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Wow. See, I've realized why I only read autobloggreen, and not the regular autoblog. I had no idea that normal people take their cars to a track.

The Tesla Roadster... is for the road.

Am I insane?

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Correct me if I'm wrong, but I don't recollect Tesla selling this car as a track-day car. If owners want to give it a try good luck to them...where's the harm in that? Meantime the car does achieve pretty much what it set out to achieve on the road....at least it will when they finally get the gearbox working as it should. If you really want an electric track-day car maybe you'd be better off with Ian Wright's X1, if he'll sell you one.

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