Tesla finally finalized its single-speed gearbox, on track for completion in August

Those Tesla folks are finally (almost) out of the woods on this whole powertrain nonsense. Its original two-speed design had many "durability, efficiency and cost challenges," but Tesla Motors decided to go with it in its first production run, and then swap in the new single-speed "1.5" powertrain once they get it just right. It's a bit funny Tesla 'fessing up to durability problems now, after denying them so vehemently before, but either way buyers of the first 40 cars that'll ship with the old powertrain won't have to wait long for an upgrade, since the 1.5 powertrain has been finalized and is slated for production in August. Tesla already has a 1.5 version they're driving regularly, and they're in the testing phase. 1.5 involves improvements to the motor, inverter and gearbox design, and improves torque among other things -- which gives that 3.9 second 0-60 spec they've always wanted.

[James Scott @ May 27th 2008 8:45PM]

Why don't they just strap on a CVS transmission from a regular car? I cant imagine it requires anything magical to drive one of those.

[Tiki God @ May 27th 2008 9:28PM]

Because a regular transmission can't handle a motor that revs to 13,000 and provides full torque in its entire powerband.

[James Scott @ May 27th 2008 10:50PM]

You fail at engines.

CVT doesnt need the engine to rev to 13000rpm. You pick an RPM and accelerate by changing the ratio. On a gas engine it hits the RPM that its most efficient and stays there. The electric engine since its pretty efficient everywhere you could pick any RPM really, and for regenerative braking have it adjust the RPM accordingly based on how hard you want to brake.

[jake @ May 28th 2008 12:54AM]

The problem with the CVT is it's still too complex and they are trying to maximize efficiency; a gasoline car might benefit from the CVT b/c of the relationship between rpm and efficiency, but an EV isn't affected by those things, so the CVT provides no visible benefits while being more complex (therefore more prone to failure, more costly). They were only forced to pick a two speed for acceleration purposes, they would have loved to not even bother with a multispeed transmission, much less a CVT, if it was possible.

Also the older motor needed 8-9k rpm to reach peak power even though peak torque comes a lot sooner (power is a factor of rpm and torque); which might play into the durability of the CVT. Also having peak torque @ 0 rpm might play into the transmission troubles too.

I would imagine it's not as easy as "strapping on" a transmission as a lot of people keep suggesting. They consulted Magna, Ricardo, x-trac (all very experienced transmission makers) and they couldn't make the 2 speed durable enough. I imagine actually the problem has more to do with insisting on lesser gears, which actually means the gap between gears will be greater, which might be causing the problem.

Anyways the details on why the 2 speed didn't work isn't as important now b/c they found a way to make the 1 speed work. You can't get more efficient or simple than a one speed, which is just basically a simple gear.

[Brady Williams @ May 27th 2008 8:58PM]

so the 1.5 gearbox is like the one that they wanted at the begining but without regenerative breaking? or does it change the acceleration

[jake @ May 27th 2008 9:48PM]

Regen braking is still there. It's better than the original two speed they planned for, because the "1.5 drivetrain" actually means the whole drivetrain is upgraded. The motor has more power and torque and better cooling/efficiency after all their listed changes. By the percentage improvement numbers they are giving, it's 325hp vs 250hp in the original and 305lb-ft torque vs 210lb-ft. The transmission is also more efficient and durable due to switching to a much simpler one speed. This means even with one gear instead of two, this "1.5 drivetrain" will outperform the original two speed. The gearing is between the original two gears in the 2 speed version.

It's good news, looks like the drivetrain is coming along. Now they need to do all the durability testing (including a visit to death valley). Looks like now at least they are on schedule so car #41 seems to be the first car that will get this new drivetrain.

[deenko @ May 27th 2008 9:32PM]

"Why don't they just strap on a CVS transmission from a regular car? I cant imagine it requires anything magical to drive one of those."

They tried and the EV drive train is too much for a regular tranny to handle.

"so the 1.5 gearbox is like the one that they wanted at the begining but without regenerative breaking? or does it change the acceleration"

Still has regen, but with all the nice new acceleration! What they did not say is that the 1.5 drive train has better overall acceleration across the entire range.

[ryan @ May 27th 2008 9:53PM]

I love it. It just wouldn't be a gadget if they didn't have to upgrade it. It's just so perfect! What do you say Engadget, Tesla Roadster giveaway? (hey, a man can dream.)

[Ian @ May 28th 2008 3:26AM]

o you do dream big don't you!

[D @ May 27th 2008 10:03PM]

Will the extra power reduce the range?

[jake @ May 27th 2008 10:12PM]

No, because a lot of the changes they made actually went towards improving efficiency too, from reducing resistance in the motor to changes to the transmission (which is now a single speed so it is much more efficient since there is no mechanism to switch gears anymore). They are expecting around 10 miles better range.

[EQC @ May 27th 2008 10:12PM]

probably only if you use it...

If you cruise along the freeway at 60mph, it's basically using the same power as before (likely in the 15-25 horsepower range to cruise on the highway).

If you mash on the gas and use all of that 300+ horsepower constantly, of course you'll drain the battery faster than if you only had 250 horses to draw out.

[glauco @ May 28th 2008 12:05AM]

Hey, there is no "gas" to mash on!
I believe you refer instead to the "amps" pedal.

[Chapsy @ May 27th 2008 11:38PM]

Is there any word on how much the car is going to cost?

[Carl Vitullo @ May 27th 2008 11:42PM]

100 Gees.

Start saving

5 years ago.

[Ace b @ May 28th 2008 12:04AM]

Dude,that info was released the moment we heard about this car.






Where have you been?

[Carl Vitullo @ May 27th 2008 11:41PM]

pshhhh, only 3.9s 0-60.
Arial Atom has 2.3s, that's all that's good for me now.

[Andrew Tanasescu @ May 28th 2008 1:11AM]

Ariel atom does it in 2.8s

so if 3.9 isnt quick enough, check out the Wrightspeed Sr-71 electric car which does it in 2.5. All it is is an electric atom

http://www.autobloggreen.com/2008/05/23/wrightspeed-sr-71-will-deliver-0-60-in-2-5-seconds/

[Flash635 @ May 28th 2008 1:51AM]

"pshhhh, only 3.9s 0-60.
Arial Atom has 2.3s, that's all that's good for me now."

I like a roof on my car.

[Ian @ May 28th 2008 3:29AM]

well i like NOT having a roof on my car.. even if it only does 0-60 in like 10 seconds plus a few more just for good measure! because i can go where the atom cant.

[Eric @ May 28th 2008 12:38AM]

Vehemently denied? Tesla has been consistent this entire time. The only thing that has been inconsistent is the reporting. Simply put, locked into a single gear, the 1.0 transmission isn't going to fail, but doesn't meet the performance characteristics originally promised. It "would" have been unreliable in two gears getting the car to 60 in 3.9 but that's not how they released it. Just because a hypothical configuration of the car might have reliability problems only shows that Tesla has been more than open about all the issues (otherwise you wouldn't even know). The only thing lacking is Engadget editors' ability to actually understand the facts.

[jake @ May 28th 2008 1:06AM]

Yep, I suppose it is confusing for some people to keep track, but the 2 speed transmissions they were referring to as having "durability, efficiency and cost challenges" were prototypes that were never even sold (only the first production model, which went to the chairman, had a 2 speed). None of the production models with the "temporary transmissions" are 2 speeds, so none of them have the durability problems, they just didn't meet the performance target as you mentioned.

Sigh, I guess sometimes you can't expect too much from blogs.

[Doug @ May 28th 2008 1:57AM]

"It's a bit funny Tesla 'fessing up to durability problems now, after denying them so vehemently before.."

You guys are a bit confused. Tesla has been open for a while about the durability problems with the Magna 2-speed transmission. What they said would be durable (referenced in the other article you link) was their temporary 1-speed tranny solution which was essentially the robust (yet way too slow to shift) X-trac transmission locked into 2nd gear.

This new 1-speed tranny of powertrain 1.5 splits the difference between the original 1st and 2nd gear ratios. The motor now supplies enough torque to match the acceleration performance of powertrain 1.0's 1st gear.

[charlie @ May 28th 2008 5:39AM]

Oh geez Jake is pissing me off. Well really it just makes me sad, because I really wanted to believe in this car, but the fact that Tesla pays employees to hype their car really makes me believe that its vaporware, as some of the most respected independent auto journalists have called it (see The Truth About Cars).

The truth is that no auto journalist has ever been allowed to drive the Roadster outside of a tightly controlled press event. This means that no auto journalist has ever been able to independently verify the supposed 0-60 times as top speeds. The truth is that nobody has been able to verify this supposed "221 mile range on the EPA combined cycle" (which, by the way, was originally 250 miles, and then dropped to 211 miles after "incorrectly estimating battery performance", before being upped to 221 by supposed "efficiency improvements in the power inverter"). Nobody has ever come anywhere near evaluating the "3 hour recharge time".

An upstart car company makes all these amazing claims about incredible performance of new technology, or often existing technology that companies like Toyota and Honda had evaluated and deemed poor-preforming for cars (ahem, lithium-ion batteries).

And then they dont let a single journalist take their car for a private spin.

And then they significantly lower range estimates, but is still using the nebulous "EPA combined cycle", which is what is used to make the mileage estimates for cars on the window sticker. Thats the test that got so much backlash for overestimating mileage even on regular cars that they had to start including a disclaimer, "test results, not indicative of real world performance", and which became even more notorious for drastically overestimating the mileage of hybrids.

And then they announce that their transmission doesnt work, with 1st gear apparently only lasting 1000 to 2000 miles.

And now they announce that their wonderful, super awesome, better than before solution is to upgrade to "a newer more efficient inverter", an "upgraded motor to handle higher current and torque", and "a new single speed transmission in between two old gears, which when combined with more torque and a higher max rpm will be able to achieve the same performance as the old transmission". "This was our wonderful plan all they time", they say (this after previously claiming that they were on an emergency mission at two new transmission firms to find a new 2-speed). "we always wanted to only have one gear".

Sorry, guys, but until you prove otherwise it looks like you slapped some more cooling gear onto the engine, rigged up a bigger inverter so you can suck more power, and are just going to run your engine harder than you were before. Which I can't imagine will be very good for durability OR mileage/range.

Same goes for all your amazing performance stats.

And none of this even makes sense: even if the electric motor has no efficiency benefits at running closer to a specific rpm (which is hard to believe), a 2 speed transmission, compared to a single gearing in between, would be able to accelerate 0-60 faster in the first gear and have a higher top speed in the second. If there is an alleged efficiency gain from this new power inverter, then you could have simply scaled down the number of working transistors to get the same power as before on fewer and meet the same performance specs as before with less electricity. If this engine makes more torque and power than before, that means it has to use more electricity than before, but yet it only claims the same mileage statistics as before...

i can easily tell that Jake is a shill from the way he deceivingly makes points. Here are a few examples:

"They consulted Magna, Ricardo, x-trac (all very experienced transmission makers) and they couldn't make the 2 speed durable enough.", by which he must mean that they were using a Magna transmission which failed, and then solicited offers to build a new transmission from Ricardo and X-trac.

"Anyways the details on why the 2 speed didn't work isn't as important now b/c they found a way to make the 1 speed work. You can't get more efficient or simple than a one speed, which is just basically a simple gear." Haha, i guess you can't get any more simple, but efficient... I call shenanigans. In electric motors, resistance losses vary with the current SQUARED. To achieve the same performance, they're adding much more current. Which will lead to that much squared in additional resistance losses. You can bet that losses from friction in the bearings and and losses to power the now more powerful engine cooling system are greater too. You can get more efficient: a two speed transmission, with a lower gear that would require less electricity to reach a certain 0-60mph performance time and a higher gear that would require less energy to reach a certain maximum speed.

"None of the production models with the "temporary transmissions" are 2 speeds, so none of them have the durability problems, they just didn't meet the performance target as you mentioned." um, actually the first 40 production models are ALL 2 speeds, they were just locked into 2nd gear which gave them SEVERELY decreased acceleration, 0-60 in 5.9s!!!

Actually reading through this, it appears than more posters than just Jake might be Tesla employees.

Hmm then heres my prediction: The next thing we're going to hear is the that the mileage estimates will have been reduced downwards again, probably because of this jack in power draw for the motor they're implementing. Lets conservatively say they reestimate to 200 miles on a full charge, but still according to the "EPA combined cycle". So these cars are going to start getting evaluated, and in real world performance nobody can get anywhere near 200 miles even driving extremely conservatively because that test is done indoors on a dynometer (no wind resistance, which become the largest force against the velocity of a car at about 45mph and increases exponentially with the CUBE of velocity) and no A/C or heating. So maybe people can get up to 180 miles driving conservatively, 150 miles driving as they normally would in any car (decently urgent acceleration, 75ish on the highway), and then 100 miles or even less in truly spirited driving that any self-proclaimed sports car should be capable of doing. And this is with a brand new battery. Tesla always claimed that they were using off-the-shelf lithium-ion battery tech,and thats how they got really nice lithium-ion power to weight ratios and quick charge times... well lithium-ion batteries have another attribute: they're capacity declines at about 20% a year when at 77*F, more at higher temperatures, less at lower ones.

So all these guys that plunked down $100k for what was claimed to be a miracle car, are gonna start being pissed when after a year they can only get 120 miles on a full charge, after a second year they can only get 95... etc




I would love to be proved wrong. I do sincerely believe that what comes after the gasoline-ICE is an electric car. I did want to believe in the Tesla. All this shadiness has made me a skeptic.

[scopey42 @ May 28th 2008 6:19AM]

I have seen and followed a Tesla For over 12 miles between San Mateo and Half Moon Bay here in California on Hwy 92. I have to say its a damn sweet ride. This section of road is very twisty and can be a lot of fun in my Subaru, I have to say the Tesla, looked at the 25 mph curves which I can take comfortably at 45-50 in my WRX, and was powering through them much faster and sharper with great acceleration. I saw it range from a dead traffic light stop to pretty damn fast in very good time. Not scientific here but its a damn nice car and I want one. No I am not a Tesla employee, I just got lucky seeing one of the road and got to follow it most of my way home.

If it can climb the hills on hwy 92 and take the curves that can rattle many other cars I think they have done something right.

[Russ @ May 28th 2008 6:21PM]

@Charlie

Tesla couldn't let other folks drive the car until it passed all the safety tests.

While not a proper journalist, Jay Leno has taken one out for a spin and he enjoyed it. Do a search for Jay Leno and Tesla to check out the 'Jay Leno's Garage' video he did. Best quote "It's a real sports car. It handles good. It's fast, and ... if this is the future, I'm not that worried." Coming from a guy with a car collection like he has, I'd say we don't have to worry about this being vaporware.