The San Jose Mercury News reports that tano kubwa have tested the Tesla. Yes, well, the buff books' jobbing journos only got a couple of hours behind the wheel. What's more (or less), Tesla gently revealed their Roadster is a "two mode" vehicle. Tesla now claims 220 miles per charge (down from 250) on "maximum range mode" and 165 miles in "standard mode." Motor Trend missed this wrinkle, and reported the higher number. Autoweek didn't mention the dual-mode deal, but reported they traveled just 93 miles on a single charge– with a limp-home aftertaste. And all the journos tested the Roadster with a "this is not my beautiful transmission" either locked into the higher of its two ratios, or, uncomfortably, not. Which doesn't square with Tesla mouthpiece Darryl Siry's claim to TTAC that the mags tested two different transmissions. In short, Tesla failed to provide journalists with a production-ready Roadster less than two months before its supposed production date.
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I guess that Tesla feel I have it in for them, but their claims will never compute.
BMW has been working for years with capacitors and super-capacitors, which they consider are required to deliver the off-the-bat torque that is considered to be BMW-performance.
We still don’t have a road-ready vehicle from BMW, though there’s been lots of noise about the technology, which was supposed to be superior to regular hybrid engines. (As if there is such a thing as a regular, good hybrid.)
Problem? Energy out = energy in, and then some. And you can get a couple of excellent standing starts, before everything calms down to “let’s hope we can coast home.”
With Tesla, the hope is that they can store copious amounts of energy in itsy-bitsy batteries, and just keep adding batteries until you’ve got enough. That’s not working out as advertised – and I think their customers, though apparently willing to pay through the nose, will get a little less positive when their battery pack is ready for replacement, due to having been “overtaxed” in very short time.
BTW – person I know is waiting for his Tesla. Was supposed to have been in his eager hands before last summer, then this fall, and now he’s been told that the first ones are coming this year. A good thing is simply worth waiting for. The Tesla? Maybe not so much.
The problem with lots of little batteries is that their inherent internal resistance rises rapidly with decreasing state of charge; but the power system and motor needs high voltage to deliver the amount of power needed (without having to use thick copper cable and a heavier motor which would be needed with larger, fewer calls and lower voltages).
That’s why supercapacitors need to be used for short-term bursts of power (in conjunction with long-term power from the battery pack); the problem is anticipating the need for power bursts, and not “wasting” energy in the supercaps (which tend to “leak off” stored energy).
Sophisticated computer control combined with driver selectable modes (i.e. “sport” and “eco”) is the only way to put the energy to its best use.
@shaker
Yes, you’re quite right. And without having access to Tesla’s design concept I couldn’t tell you whether they are planning on capacitors (which are chiefly good for bursts ofacceleration, anyway.)
But I do know that anyone even approximating regular performance car behaviour with the throttle in a Tesla is in for a disappointment after a few runs.
Didn’t you get mad at me when I said you weren’t objective? I think when I said that you wished a pox on my family or something. Well, you were mad.
In the auto week article Mark says he went from 95% to 21% and went 93 miles. Do the math and that corresponds to 125 miles for the full charge on his drive.
Mark drove the car as aggressively as anyone has, with the top off, all heaters blaring, seat heaters on, and a big guy (me) in the passenger’s seat.
Just like with a gas car, mileage varies significantly with usage. My EVO gets about 20 mpg on the highway under the best case. Drive it as I normally do (fast) and I get 15. Drive it very hard and I get about 11. I measured my mileage on the track and it was about 6 mpg. Electric cars follow similar rules of physics.
Read Csaba’s review in C&D and he gets a very different figure. He drove differently.
Drive moderately and you will indeed get the 220 miles stated.
And the transmission he drove that distance was indeed the xtrac that we are starting production with. The other car he tested (there were two) had the 2 speed.
But you are right – the cars we tested were not production cars – that is typical for first drives. They are very close to production intent but not production cars.
Siry:
In the auto week article Mark says he went from 95% to 21% and went 93 miles. Do the math and that corresponds to 125 miles for the full charge on his drive.
Hang on. AW clearly stated they got 93 miles on a charge. And although Car & Driver “did the math,” extrapolation is NOT the same as proper empirical data.
You can prevaricate all you like about the difference between caning a sports car and pottering about, but 120 miles vs. [an unsubstantiated] 220 miles is a big ass gap.
C&D may have tested two separate transmissions, but it sure doesn’t read that way.
As for your admission that the cars aren’t ready for production, why not? And if so, do you really think you can deliver cars by your latest promised delivery date? March is only 32 days away.
Meanwhile, rest assured that we wish your house no ill. All we want is objective performance data. So how about lending us a car so we can give it to an independent scientific organization to establish the Roadster’s performance parameters once and for all? I mean, until you get the new transmission which you’ll swap with the old one.
120 miles vs. 220 miles is a pretty big gap but I can easily get anywhere between 8mpg and 16mpg city in my Vette depending on how heavy my right foot is feeling. If somebody gets 120 miles of range driving aggressively getting 220 miles driving conservatively is not out of the realm of possibility
Just like with a gas car, mileage varies significantly with usage.
True. The difference is that if I want more miles between fill ups, the automaker can offer to put in a bigger gas tanks. What do you offer the [potential] Tesla buyer who wants more miles between charging? Come back in two years?
My EVO gets about 20 mpg on the highway under the best case.
Good to see you guys are dedicated to saving the planet. If When Roadster sales take off, what are you planning to get? A Hummer? Perhaps something more roomy?
So how about lending us a car so we can give it to an independent scientific organization to establish the Roadster’s performance parameters once and for all?
What TTAC is not an independent scientific organization. Boy, talk about disappointment.
From the article:
“We got 93 miles out of the full charge we had on our day’s drive, which was, as we said, spirited and over twisting mountain roads. The meter on the dash went from 95 percent charge to 7 percent by the time we got back to San Carlos.”
It went on to say that that 7% (sounds like a “virtual number”) became 21% when the car switched over to power-conservation mode.
That’s still very low, on what really was a very short trip, mountains and twists notwithstanding. I can do 100 miles just going to school or running errands. There would be not enough juice left for an evening dinner for two after a typical weekend day in my car.
Incidentally, anything below 25% to 30% SOC (State of Charge) is considered a “deep discharge,” and significantly shortens the life of the battery pack, regardless of what the battery is made of.
I learned this while I researched hybrids and batteries, just before I bought my Prius, and that’s why the Prius’ batteries last so long, the computer never lets the SOC go below 40% or so.
Armed with that knowledge, I’m now able to extend the life of all of my batteries. I don’t let my camera, laptop, or cell phone batteries go below a 40% SOC, except in rare case of bona-fide emergency.
But back to the car. I don’t think the range is long enough, especially if the driver is prudent and seeks to limit deep-discharge cycles.
Engineer:
TTAC is an independent organization, but not one with ALL the in-depth scientific knowledge and equipment to thoroughly test all the battery and distance claims of the Tesla.
For that, I’m sure you’d need a lab, a dyno, and multiple charge/discharge cycles to get a good average of benchmarks. Plus a little bit of the fun, real world testing.
SexCpotatoes : I specifically stated that we want someone else to do the scientific tests. We know our limitations. Of course, that's just a dream. Tesla has shown themselves singularly unwilling to face a rigorous independent examination of their vehicle's technology: from performance, to recharge time, to range, to safety, etc. What does that tell you?
I’m sorry, but I don’t see how anyone could shell out 100K for a “Sports Car” that can only be used as a sports car on rare occasions, unless you just happen to be cruising around your block.
I want to know what’s under the hood. I didn’t see it being used for storage, and the engine is in the rear, so there should be at least a bit of extra space, right? Why couldn’t a range-extending gasoline engine be placed in there? Something extremely small, only capable of charging to batteries while driving to help extend the drive time? Or, as others have suggested, what about a chain of supercapacitors? Whenever the engine isn’t being held at-speed, the acceleration could come from these instead of the battery, which could be quickly recharged from braking.
(Or, seeing as how 93 miles gets many people TO their location and not back, maybe an emergency fwd motor for getting home when you eventually do run out of juice could be installed… of course, taking cues from the ill-fated and unsuccessful Prius wouldn’t be too wise, would it?)
–Then again, what do I know? I fix computers for a living… Maybe Tesla has it right.