Tesla Roadster Data Logging Format Reverse Engineered

s1axter writes with word that "the data log format for the Tesla Roadster has been reverse engineered and documented, now available in Python. (Python script linked in the post.)" From the linked blog entry: "Not only was I given a $110k car unrestricted I was requested to see what ECU information is available, collect and parse the data from it. Tesla Motors periodically collects information from their vehicles presumably to see what real-world driving the cars see. On original Roadster models there is no method to collect this information remotely thus someone must go out to the vehicle and collect it. The owner of the vehicle saw this and wanted to know what information was collected on these service calls ... Because I am a big fan of freedom to modify a program to fit ones needs, I have uploaded the ... python script to parse Tesla logs."

Comments

queue the lawsuit

[bananaquackmoo]

lawsuits and streissand effects coming in 3...2...1...

Re:queue the lawsuit

[bobdotorg]

lawsuits and streissand effects coming in 3...2...1...

No big deal. Most modern cars have, to some degree, a black box.

One car company even 'gives you one for free': you can hit the rev limiter fuel cutoff once a year, any more and you void the warranty for parts excessively worn by over revving. (dammit - I can't find the cite right now. The google is weak in me today.)

Re:queue the lawsuit

[transfatfree]

apparently in Canada, the Streisand effect can now be called the Bubble Effect.

Thanks Officer Bubbles!

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[Fluffeh]

lawsuits and streissand effects coming in 3...2...1...

I wonder if you could counter-sue through copyright of data. Unless there is a clause when buying the car saying that the company can copy data from your property, it is by rights, your data and when they download this black box of data they are infringing. Given that it is indeed a black box, an even better argument might well be that they are not only infringing on your data, but also blocking you from accessing your own data.

Lock and Load!

Re:queue the lawsuit

[vipvop]

The rev limiter is there precisely so you don't hurt anything, once a year would be ridiculous. What it can't stop is people with a manual transmission shifting to a lower gear when the RPMs are too high, which will create an unavoidable over-rev situation.

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[Anonymous Coward]

The problem with your argument is that there's nothing to go on.

I can't even see evidence Tesla actually cares one bit.

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[Anonymous Coward]

It will happen sooner or later. This may be the start of car manufacturers acting like asshole device manufacturers that prevent customers from treating the product how they like. E.g. Apple and Sony.

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[geekoid]

One over rev isn't going to destroy any modern engine. It's the long term effect that they are curbing. Many very tine bits of damage acquired over time can be hard to differentiate from a 'bad' engine.

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[Anonymous Coward]

You can hit fuel cutoff rev limit all day long, all year long and your warranty is not voided. The engine has been designed to operate up to that speed by the manufacturer, that's why the rev limiter is in place. Over revving is what voids the warranty, and on any modern car there is only one way of over revving, called "mechanical overreving" or "money shift" -- imagine an engine with a 8000rpm redline, shifting from 4th to 5th at said 8000rpm, and by accident actually downshifting into 3rd. This results in the engine spinning at 9500 or 10000 rpms for a second or two, possibly damaging the rod bearings, the crank, the valvetrain or the pistons, if there is contact between the crown and a valve that didn't close fast enough.

Re:queue the lawsuit

[cosm]

StupidShitCorporationsDo.Enqueue(Lawsuit);
BullshitThings.Add(StupidShitCorporationsDo.Dequeue());
BillshitThings.Dispose();

Could have saved time by just ignoring the suit. Shame society doesn't for the frivolous ones.

Re:queue the lawsuit

[Anonymous Coward]

Why wouldn't the rev limiter set at or below redline? And why isn't redline the max safe RPM? Warranty should be void if redline is exceeded, not achieved. (Like downshifting into too low a gear, for example.)

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[John Hasler]

In the USA data is not protected by copyright. Besides, you gave them permission to copy it. As for "blocking" your access to the data: how are they doing that? You have possession of the car and are free to do anything you want to with it.

Re:queue the lawsuit

[Anonymous Coward]

Not sure how that's applicable to a Tesla story, the car only has one gear.

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[Bigjeff5]

I wouldn't expect any lawsuits, reverse engineering is well established as a legal activity.

Now, there may be some DRM on the logs in the future, at which point reverse engineering suddenly becomes illegal.

God I hate the DMCA.

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[ffreeloader]

One over rev isn't going to destroy any modern engine. It's the long term effect that they are curbing. Many very tine bits of damage acquired over time can be hard to differentiate from a 'bad' engine.

That depends on how far the engine goes above the redline. Sure over revving an engine 500 or 1000 rpm once or twice in its life time won't kill it, but what about 3000 rpm a time or two by doing something like going from 5th to 2nd gear at high speed? Chances are winding it up that tight is going to cause some damage and cause a measurable shortening of its lifespan. It may even destroy it right then and there by throwing a rod through the block or hitting a valve with a piston..

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[Edmund Blackadder]

Hmm, the manual cars I had would simply not let you shift that low. There was some kind of mechanical thing that would prevent you from shifting into low gear if you are driving fast even if you had the clutch fully pressed.

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[Bigjeff5]

It would be very tough (read: impossible) to argue that data logs automatically generated by an ECU constitute creative content, and it is creative content that is copyrightable. Furthermore, the data logs would more than likely be owned by the owner of the car, not the company that built the car. Ergo, the owner of the car would own the copyright on the logs (if such a silly thing could exist).

Now, if you got a hold of the ECU's source code, that is a different story, but reverse engineering the ECU software is perfectly legal.

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[dakameleon]

You mean the Synchromesh?

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[dakameleon]

The redline is the maximum RPM at which the engine is "safe", in that it is within design tolerances. Operating above the redline is possible, but basically at that point they're saying "you're on your own." Cutting off right at the redline would be keeping everything safe, but doesn't allow for the occasional need to go over, such as in the accidental example of missing a gear on the downshift - far better to allow a 5 - 10% overrun than to punish that with an immediate limit.

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[Anonymous Coward]

lawsuits and streissand effects coming in 3...2...1...

No big deal. Most modern cars have, to some degree, a black box.

One car company even 'gives you one for free': you can hit the rev limiter fuel cutoff once a year, any more and you void the warranty for parts excessively worn by over revving. (dammit - I can't find the cite right now. The google is weak in me today.)

You do realize that you arent 'over revving' if you hit the fuel cut. Your only 'over revving' if you shift into say 2nd, while at/near redline in 3rd.

Oh man. What a post >_>

Re:queue the lawsuit

[WoLpH]

Usually you can shift it into the gear you want, you just have to push a bit harder ;)
Most cars also try to prevent you from shifting to the 1st gear when you're still going 50 kilometers an hours while breaking for a traffic light. Just push a bit harder and you'll succeed easily.

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[Kakari]

Yes, pushing harder will get it in gear, but at the expense of shortening your synchros life - much better for the transmission to hold off on ramming it into first until you're slow enough that it slides in easily. Or just leave it in neutral, let the clutch out and use your brakes. When you're ready to go again, just shift into first.

Remember: brakes are almost always cheaper than a clutch or a transmission rebuild.

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[Lord Maud'Dib]

Or double clutch to get it into that lower gear for the corner while braking to slow the car up.

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[SimonTheSoundMan]

Oh goodness no, they could have some fancy American "software patents" for their ECU software. *shakes head*

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[Anonymous Coward]

Forget the stupid "void the waranty by hitting the limiter" comment .. Thats just insane.

Can you please cite some reference to a rev limiter that is based in anyway on/in the fuel system ?

Any/all rev limiters I have ever worked with have all been on the spark side of the power triangle ( compression / spark / fuel )

Playing with the fuel flow can cause way too many problems. A lean system can destroy an engine.

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[Anonymous Coward]

I CALL GODWIN!!!

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[DigiShaman]

Since the invention of the fuel injector, gasoline has been metered appropriately. Prior to that, cars used a carburetors which tended to run the fuel mixture too rich. This causes excessive washing of oil from the cylinder walls thus causing exponential wear and tear on the engine depending on RPM.

Now days with tight clearances, improved metallurgy, oils, and computer controlled injection; running high RPMs will not have that much of an effect on its life. If anything, you suffer fuel economy.

I used to drive my 99 Miata like I stole it. I actually tried to destroy the engine. I would float the valves often for the hell of it. This lasted for about 160K miles before I got rid of it (bought it used with 34K on it). Spark plugs indicate a clean burn (nice tan color), valve train and cam lobes in primo condition, and excellent compression on all four. Yup, engine tech has come a long way.

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[plover]

Now days with tight clearances, improved metallurgy, oils, and computer controlled injection; running high RPMs will not have that much of an effect on its life.

These days they're using the tight tolerances to build torque via intentionally higher RPMs instead of bigger pistons or increasing compression. It saves on fuel and engine size. But the higher RPMs create higher forces on the moving parts, "taking up" the slack the tighter tolerances and better materials gave them. Revving the engine over the manufacturer's published spec still risks damaging it.

Re:queue the lawsuit

[FatdogHaiku]

Now all we need is an XKCD link and we're all set...

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[darthdavid]

Of course make sure not to be breaking when you actually get into the corner, good way to slide off the road...

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[DigiShaman]

You mean they are relying on higher RPMs with fewer pistons to create additional HP. Which makes sense given how some i4 engines can approach the same levels of power to that of a v6. But notice the displacement of these i4s. The pistons are massive in comparison to the smaller ones in a v6. By consolidating your displacement into fewer cylinders, there's less friction robbing you of power.

Running at higher RPMs is not fuel efficient by itself. But depending on the cylinder count and overall displacement, I suppose in theory, a higher revving i4 can be more fuel efficient compared to a low revving v6. Again, buy virtue of less friction and reciprocating mass.

Re:queue the lawsuit

[Anonymous Coward]

Umm...pushing harder isn't really to be recommended. The preferred technique is known as double clutching, required with the old-style "crash box" (non-synchromesh) transmissions common in race cars and big trucks. It involves momentarily re-engaging the clutch while in neutral and synching the engine speed up or down to match the gear you're going to. Indeed, a really adept double clutcher can dispense with using the clutch altogether except when coming to a stop, and shift quite smoothly - yes, even into first. (I used to do this in my show-off high school days.)

Of course, this technique requires deliberately blipping the engine up a few rpm for a downshift, so there goes our conservative revving....

Re:queue the lawsuit

[Anonymous Coward]

http://xkcd.com/688/

Re:queue the lawsuit

[Gordonjcp]

Which makes sense given how some i4 engines can approach the same levels of power to that of a v6.

Most I4 engines in European cars are more powerful than American V6 engines. I mean, Ford are still releasing engines based on the ancient Essex blocks, albeit drilled out to 4 litres, but they're still thirsty, clattery gutless boat anchors. Hell, the I4 turbodiesel in my van is quieter and more powerful than most Yank-tank petrols...

Re:queue the lawsuit

[Gordonjcp]

Any/all rev limiters I have ever worked with have all been on the spark side of the power triangle ( compression / spark / fuel )

Every car with a rev limiter in then engine ECU accomplishes it by cutting the fuel off. If you turn off the ignition, you continue to blow unburnt petrol vapour down the exhaust, where it will ignite in a spectacular killswitch backfire as soon as the ignition kicks back in. It will also destroy the catalytic converter.

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[RMH101]

Hang on, I think there's some confusion here. First off, hitting the rev limiter does not damage your car. If revving at that level was going to cause damage, the rev limiter would be set lower. BMW's older M3 with clutchless manual SMG had a hidden feature where you could enable launch control by a combination of button presses, which would allow you to from rest floor the accelerator and on click into first gear it would launch at max attack. They enabled a feature where after 5 such actions they would void your transmission warranty.
Is this what you're thinking of?

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[GooberToo]

What it can't stop is people with a manual transmission shifting to a lower gear when the RPMs are too high

Actually you can. Its called gear lock-out. When shifting to a gear would result in an over rev, the transmission can lock out the gear preventing the driver from shifting to the gear. My car has such a mechanism.

Besides, I've never even come close to noticing the lock-out unless I'm driving extremely aggressive, in which case, it has saved me from down shifting too low. The result, the vehicle is protected from driver abuse which seemingly, only results in extremely atypical driving conditions.

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[maxume]

Ford's 3.5 Liter Ecoboost engine is putting out 350+ hp and 350+ foot-pounds of torque. I sort of doubt your van matches that.

Re:queue the lawsuit

[maxume]

It doesn't really seem there is any way to immediately limit a mechanical over-rev (well, not one that would do less damage to the engine than the over-rev).

Re:queue the lawsuit

[maxume]

I get the sense from a couple of GM vehicles that I have driven that the ECU is also limiting fuel input in order to protect the clutch and transmission (i.e., the damn things barely drag themselves up a hill even with the pedal on the floor; and yes, I realize I should probably downshift).

Re:queue the lawsuit

[s122604]

"Most I4 engines in European cars are more powerful than American V6 engines. " -- Citation please?

Re:queue the lawsuit

[s122604]

Even tamer V6es like the ones going in the Chevy Malibu are in the 250HP range.

Buick's putting one in the lacrosse that goes around 380 or so..

There is no snobbery like euro auto snobbery, I think some of them actually believe that their low end VW, or opel or whatever would actually out-corner a Z06....

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[GameboyRMH]

One car company even 'gives you one for free': you can hit the rev limiter fuel cutoff once a year, any more and you void the warranty for parts excessively worn by over revving.

Reason to buy an old car #36,759

(the first 20,000 reasons are the dollars the car depreciates by in its first two years off the lot)

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[GooberToo]

There are basically two ways to make horse power. One is by brute force (large displacement; generating torque). The second is by high RPM. Illustratively but not completely accurate, hp = torque*RPM. Typically, large displacement means large reciprocating mass. This is the antithesis of high RPM and reliability. Likewise, high RPM typically means low displacement with and associated lower reciprocating mass.

Classically these two ideologies have materialized as large American V8s versus small European/Asian engines. Improvements in materials and manufacturing capabilities has steadily been allowing for a move to the center which provides for a more idealized realization of the two ideologies while realizing yet additional benefits; which you are highlighting.

Re:queue the lawsuit

[tibit]

Someone in charge of ECU software design must have been asleep at the desk. Any engine over-rev on a manual gearbox should be immediately mitigated by applying compression braking. With this in effect, I can't really understand what's the problem. Sure, someone who chose a wrong gear and over-revved the engine will have to deal with effects of braking, possibly doing skid recovery and whatnot. In any case selecting too low of a gear with too little throttle applied will always cause the drivetrain to drag like crazy.

Re:queue the lawsuit

[GameboyRMH]

It could be made impossible on a robotized manual transmission - if it gets a command to downshift that would send the revs too high, it just stays in the current gear, and if somehow it's in engine braking and still going too high (maybe going down a steep hill in a higher gear) then disengage the clutch and shift into neutral - although this could put the whole car in danger.

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[GooberToo]

I will point out that citing HP numbers is the absolute worst way to compare any two different engines. Horsepower, in of itself, is an almost useless metric for comparison of anything.

Horsepower numbers are a great concept used by magazines and manufacturers for people who generally don't know anything about engines or vehicles. Car and Driver is a great example. Its for people who know nothing about vehicles but want to pretend they do. If you know a religious Car and Driver reader, with few exceptions, you've identified a seriously pretentious, and almost completely ignorant, douche bag.

Re:queue the lawsuit

[tibit]

I'd be careful with this argument. A painting is basically a mechanical log of painter's hand position over time. A book is basically a mechanical log of a bunch of keystrokes. While driving is mostly utilitarian by nature, there are drivers who "play" with their cars -- do things that are creative in nature and not merely utilitarian. Just like book writing can keep food on the table, driving can get you to your destination, but still you can be creative: play with brake lights, engine revs, etc. A log of an average soccer mom's grocery shopping trip is probably not in the scope of copyright law, while someone's who played a beat with the engine while at the red light -- probably would be in scope.

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[geekoid]

Yeah, no hit. To extreme abuse will be obvious. Clearly that wasn't my point. In the events you are talking about are called 'throwing a rod' or 'destroying the transmission', or 'blowing a gasket' NOT over reving.

OTOH, your sig is a pretty clear indicator your an idiot.

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[geekoid]

yeah, he didn't say NO risk. Just to bring you up to speed, they also use better and stronger materials.

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[GameboyRMH]

A lot of cars with automatics have the RPM limiter set lower than the same car with a manual, because the auto trannies can't take the higher revs, while the manual gearboxes would happily go to twice the engine's max RPM.

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[Anonymous Coward]

As far as I'm aware, there is no such thing. The number of solenoids or other electric-over-mechanical devices you'd need in a manual transmission specifically to lock out those gears would make it unprofitable.

The device that makes it very difficult to shift into too low of a gear at high speed is called a synchronizer. It's main purpose is to synchronize the input shaft (clutch) RPM with the output shaft (driveshaft) RPM before you reapply the clutch. Prior to it's invention, you had to match RPMs using the engine, or you would grind the spur gearing inside the transmission. Downshifting from 6th to 5th would increase the clutch RPM, and then when you reengage the clutch, the engine speed picks up to the clutch speed.

Downshifting from 6th to 1st is not impossible, but you're using the synchronizer to try to spin up the clutch to some insane RPM, and the blocking rings in the synchro won't allow the gear to fully engage until you've reached that RPM. At which point, you would reengage the clutch and your engine would try to reach that insane RPM.

In short, next time push harder.

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[GooberToo]

As far as I'm aware, there is no such thing.

Factually there is such a thing. Just do some searches for "gear lockout". Typically its done on first, first and second (typically 4+1 tranny), or first, second and third (six speed tranny [4+2]), as those are the gears where over rev is far most likely. The thing is, you really don't need a complex set up to lock out gears because all previous gears are also inclusive.

In short, next time push harder.

In short, next time learn about the subject before you post.

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[s122604]

The only time I read car and driver is in the doctors office, and its usually a year or so old...

now to your point "Horsepower, in of itself, is an almost useless metric for comparison of anything" -- yes and no, the submitter said "The I4 turbodiesel in my van is quieter and more powerful than most Yank-tank petrols."

Sorry, but if you are making a reference to "powerful", then yes horsepower needs to be considered.
Is it everything no, of course not, lots of other things can be considered, but it's not "almost useless"

Now, somebody is going to chime in about torque, yes I know about torque, and these V6 designs certainly are no slouches there either.

But ultimately torque is not some magic concept that is independent of HP.
.HP = Torque x RPM ÷ 5252 is not just a rule, its the law...

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[plover]

My point was that all other things being equal, higher RPMs can yield more power. But you're right, if you can cut cylinders, you can get back to the original amount of power while saving on friction and reciprocating mass.

Cutting cylinders also saves on overall mass. Ford's V6 3.5L Ecoboost produces 365 HP and weighs 449 pounds. A Mustang GT's 315 HP V8 weighs over 525 pounds. Getting rid of two cylinders shaved 75 pounds off the engine block while using other technology (twin turbochargers, etc.) and modern materials to produce more power reliably. I emphasize that last word because these are in consumer vehicles that are expected to last for hundreds of thousands of miles.

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[Anonymous Coward]

"Most I4 engines in European cars are more powerful than American V6 engines. " -- Citation please?

According to numbers pulled directly from my ass, and because of my own bias against anything American possibly being good, I pronounce it a fact.

Just for grins, "most 4 cylinder inline engines in European cars" might today mean the Renault F4R-type engine, which puts out 170 HP, and powers vehicles across the entire Renault family. And "American V6 engine" means the plain old Ford Duratec 30 engine, which replaced the Essex back in 1996. It put out 201 HP. And in my world, invisible pink math unicorns make 170 greater than 201.

Or set the wayback machine to the introduction of the maligned Essex engine, which put out 112HP the day it was introduced in 1983, but was boosted to 140HP as the standard back in 1988. Compare either of those to the biggest I4 engine they ever stuck in the Renault 5, the 108HP Renault Cleon C2J.

That's the trouble with invisible pink math unicorns. You can never find them when you need them.

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[ffreeloader]

Since the invention of the fuel injector, gasoline has been metered appropriately. Prior to that, cars used a carburetors which tended to run the fuel mixture too rich. This causes excessive washing of oil from the cylinder walls thus causing exponential wear and tear on the engine depending on RPM.

Now days with tight clearances, improved metallurgy, oils, and computer controlled injection; running high RPMs will not have that much of an effect on its life. If anything, you suffer fuel economy.

I used to drive my 99 Miata like I stole it. I actually tried to destroy the engine. I would float the valves often for the hell of it. This lasted for about 160K miles before I got rid of it (bought it used with 34K on it). Spark plugs indicate a clean burn (nice tan color), valve train and cam lobes in primo condition, and excellent compression on all four. Yup, engine tech has come a long way.

You're missing the point.

The reason an Formula 1 engine can withstand the rpms they do is because of type and quality control of materials, closeness of tolerances in parts manufacturing, how closely the rotating assembly is balanced, and the quality control exerted over the parts used in the engine(each individual part is examined externally and internally for any flaws), etc....

The care taken in building a racing engine cannot be used in a factory situation. It would add 10's of thousands of dollars to the cost of your car.

This means that a factory stock engine is built to far lower specifications than a racing engine. They will self-destruct if you accidentally turn the kind of rpms at which a racing engine routinely runs. The redline on the tach in your car tells you what the factory thinks is the upper limit of rpms the engine can safely turn without causing damage. Thus, if you take a stock engine with a redline of 6500 rpm and turn it 9750 rpm by downshifting from 5th to 2nd gear you're most likely cause a fair amount of damage, if not cause it to self-destruct immediately. Why? Because you've gone far past the forces the stock parts were designed to withstand. You've exceeded the specs for the engine parts by 50%.

Now, with a rev-limiter, or the built-in rev limiting created by causing hydraulic lifters to float, you've never going to reach that 9750 rpm that will cause parts to fail using the throttle. However, lifter float won't save you, and neither will a rev limiter if you downshift too many gears as you're mechanically forcing the engine to run that fast through the transmission gearing and the speed of the car.

As far as trying to destroy engines through abusing them, the toughest engine I've ever encountered was the old 235 cu. in. inline 6 that Chevy built during the 50's and 60's. I had a 1962 2 door hardtop Chevy BelAir with that engine it when I was in high school. I wanted to take out that 235 and replace it with a 327 so I could do some hotrodding. But, my old man, who was a mechanic, told me he wouldn't allow it unless that 235 failed. So, I used to take that car out into the country and run it in 1st gear with the valves floating for 10-15 miles at a time. When that didn't do the trick I quit changing the oil and kept on abusing that engine.

I never was able to hurt that engine although I tried to blow it up for 2 years. Back then with the square cut gears and type of synchros used in the manual transmissions you couldn't downshift directly from 3rd to 1st as the gears would just grind if you couldn't get the rpms high enough with the throttle to mesh the gears so I couldn't blow it up that way.

I did do some hotrodding after I got out of high school, and I built some carbureted small block Chevy V8s that would turn 8000 rpm without hurting them, but the quality of parts, internal tolerances, care of assembly, balancing of the rotating assembly, etc... were all much different than a stock motor.

Re:queue the lawsuit

[Jaime2]

Actually horsepower is about the only number that can be reasonably compared between different engines. Any engine of the same peak horsepower, when connected to a perfect continuously variable transmission and installed in a vehicle of the same weight, will accelerate identically. Sure, the real world will add variables, but the engine won't be one of those variables.

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[Anonymous Coward]

Every car with a rev limiter in then engine ECU accomplishes it by cutting the fuel off. If you turn off the ignition, you continue to blow unburnt petrol vapour down the exhaust, where it will ignite in a spectacular killswitch backfire as soon as the ignition kicks back in. It will also destroy the catalytic converter.

Cutting off the fuel and turning off the ignition are two separate controllable ECU functions.

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[ffreeloader]

Here, let me be as snarky as you are....

What do you think happens to engine rpm when you shift from 5th to 2nd gear? Engine rpm climbs dramatically. If you're going fast enough it over revs the engine almost instantaneously. In a front wheel drive car the situation is even worse than in a rear wheel drive vehicle as the weight is thrown onto the front wheels increasing the tire traction and making sure engine rpm stays higher for a longer period of time.

Only an idiot thinks that the only way to over rev an engine is with the throttle.

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[ffreeloader]

Someone in charge of ECU software design must have been asleep at the desk. Any engine over-rev on a manual gearbox should be immediately mitigated by applying compression braking. With this in effect, I can't really understand what's the problem. Sure, someone who chose a wrong gear and over-revved the engine will have to deal with effects of braking, possibly doing skid recovery and whatnot. In any case selecting too low of a gear with too little throttle applied will always cause the drivetrain to drag like crazy.

There isn't enough compression braking in a gas engine to stop over revving an engine in this scenario. For proof of this try driving down a steep hill in a heavily loaded gas engine powered vehicle. What you will find is that even in lower gears you will have to use the brakes to keep the engine from over revving. Then do the same test in a diesel powered vehicle equipped with a compression/exhaust brake installed. The difference will be immediately apparent as a diesel engine with a Jake brake can create more braking horsepower when using the Jake brake than the horsepower it can create when using the throttle.

This test is the equivalent of shifting down several gears at high speed with respect to testing the compression braking characteristics of a gas engine as you are applying the same levels of force to the engine in both scenarios.

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[marcello_dl]

What about torque?

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[Jaime2]

Try this someday: Run a standard transmission car down a measured section of road twice. One time shift so that the engine stays as close as possible to peak torque and one time shift so that the engine stays as close as possible to peak horsepower. You'll find that the car accelerates much better at peak horsepower than peak torque.

Torque isn't abstract enough for valid comparisons. For example, it's really easy to boost torque by changing gearing. If an car company wanted to, they could simply add a 2:1 reduction gear inside the engine, call it a "harmonic balancer", and presto the engine now produces twice as much torque as it did before.

The easy way to make torque a useful number is to multiply it by RPM, because the same torque made at twice the RPM is really twice the torque if it is reduced down to the original RPM. We call this number "horsepower".

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[GooberToo]

Absolutely wrong!

Torque is the useful metric. Furthermore, as HP is directly derived from torque. So if you know the torque curve, you know the HP curve. Regardless, neither provide much meaning without a corresponding torque curve.

Which is faster? And engine with 100 HP or an engine with 1000000 HP? If you can answer correctly, then you're smarter than the rest of humanity. If you can't answer, then you now understand exactly why HP by it self is a completely useless metric for comparison for laymen.

Basically, anyone who goes around quoting HP numbers, without lots and lots of additional context, are putting themselves out there to be an idiot. Which is, after all, entirely my complaint of religious Car and Driver readers. They read and spew and bunch of crap, but have absolutely no idea what it is they speak about.

Re:queue the lawsuit

[GooberToo]

You're conflating several items and are completely wrong. Read my other reply in this read. You're also conflating peak HP/torque with a usable torque/HP band.

Torque isn't abstract enough for valid comparisons.

And frankly, that statement is just dumb. Hp is an abstract and so much so, its useless for comparison of different engines (read original context - which you dumped). Furthermore, HP is a function of torque. So if you know the torque and its curve, you know the HP.

Furthermore, the biggest problem with citing HP numbers is you are citing peak. Peak is almost always an absolutely useless number. Furthermore, if speed is important, the shift point is typically far short of peak HP numbers - somewhere between peak torque and peak HP.

Furthermore, quoting HP has completely different meaning when talking about two completely different engine technologies (example, large displacement, low RPM vs small displacement, high RPM); plus everything in between. Plus, without a torque curve, you have absolutely no idea how long it took to build the associated RPM. So if it takes you 30-seconds to reach peak HP, the race is lost. Likewise, HP numbers say nothing of everything else which makes a car a car (traction, gearing, transmission, shit points, etc).

Basically, anyone who believes HP numbers are a good basis of comparison (for different engines - as stated in original context) prove themselves to be completely ignorant of the topic at hand.

Re:queue the lawsuit

[GooberToo]

Power is torque. HP is work. You can have a more "powerful" engine despite having less peak HP. That's entirely why diesels are popular for work trucks. But frankly, "powerful" is a highly subjective claim anyways.

Read my other replies in this thread to become enlightened.

Well you know...

[Microlith]

When I get my hands on a $110K electric car I'll be sure to try it out! Might be a while, though.

Re:Well you know...

[geekoid]

Have you asked?

I was listening to a report on the New porche. The person doing the report called the dealer, and the dealer delivered the 100K+ car to his apartment. Then just left the keys with him. Never checking who he is.

Re:Well you know...

[camperslo]

All we need now is a way to plug in the smartphone of our choice, the script ported to phone apps, and a dealer willing to let us take a Roadster out for some test driving. To be a valid test drive, one should get to go until the fuel/power runs out.

Re:Well you know...

[by (1706743)]

I was listening to a report on the New porche.

I found the report on the New gazeboe much more entertaining.

Re:Well you know...

[Anonymous Coward]

At least it wasn't a rare Dread Gazebo.

Re:Well you know...

[geekoid]

I don't know whats worse, the facts that I misspelled Porsche, or the fact that you think that's how to spell porch.

Re:Well you know...

[BancBoy]

I don't know whats worse, the facts that I misspelled Porsche, or the fact that you think that's how to spell porch.

Whooshe!

Re:woohooo

[haruchai]

But it's a wicked fast pile of duck shit - it slides by you so fast, it doesn't leave a stain - and that's from a standing start. Besides, there are many overpriced piles of automotive avian ejectamenta - I'd sooner own a Tesla than any other, even a Porsche or ( although my teenage self would shudder to hear my middle-aged self say it ) Lamborghini

I knew it!

[Anonymous Coward]

It's all an evil scheme to find out how many Starbuck's Lattes' I get in a week.

Re:woohooo

[by (1706743)]

But it's a wicked fast pile of duck shit...

Not really. Its top speed is a "mere" 125 mph, something my 33 year old Porsche can (or could, when new) beat.

As far as acceleration goes, though...yeah, it's very zippy.

Please move along ... nothing to see

[140Mandak262Jamuna]

All he is doing is bragging about a python script that he himself admits to be simplistic and ugly. The binary format was decoded by two other posters in a bulletin board who also wrote a windows parser but the original guys did not think it warrants any kind of bragging like this. And he is not posting the logs either due to privacy concerns. So unless you are curious about seeing someone's ugly hack of a python script, just move along, there is nothing to see here.

Re:Please move along ... nothing to see

[Bigjeff5]

a python script that he himself admits to be simplistic and ugly.

Isn't that statement redundant? All python code is simplistic and ugly.

.

I kid! I kid!

Re:Please move along ... nothing to see

[Anonymous Coward]

but he admits it

Re:Please move along ... nothing to see

[Degro]

Hey, at least he's not trying to sell anything. This is a step up from the usual slashvertisement/slashnouncement 'stories'. Anyway, I thought building on top of other people's work was still a good thing around here.

Re:Please move along ... nothing to see

[Anonymous Coward]

Ok, I happen to have a Tesla and in trying to hack it so I can attach it to my solar grid I have not been able to find said easily available scripts. The only ones provided exist as one guy who will send you a decoded file if you send it to him over email as he does not publish the fill script. So unless you have first hand knowledge and happen to decode your tesla data files every day sit down and shut up.

Re:Please move along ... nothing to see

[randallman]

I think you're being too harsh. I looked at the script and it's very short and fairly easy to read. How can you complain about that? I couldn't get to the website to download the Windows tool, but I'm going to guess it's a compiled exe (could be wrong), which means it's not easy for the user to edit. By contrast, the user can easily tailor the Python script to fit their needs. In addition, the script also serves as format documentation. He clearly commented sections such as "daily record", "error record" and "1 second record".

Re:Please move along ... nothing to see

[Gordonjcp]

Isn't that statement redundant? All python code is simplistic and ugly.

That's true of any very high-level language, like Python, Ruby, Haskell, Pascal or C.

Slashdot requires you to wait between each successful posting of a comment to allow everyone a fair chance at posting a comment.

It's been 1 minute since you last successfully posted a comment

Dear slashdot janitors,

Between your stupid "It's been 20 seconds since you hit reply", the entirely unusable new comments system, the "new" user pages and this seemingly random delay before you can reply to another post, you are slowly making your site harder and harder to enjoy using. Do you really want to drive readers and commenters away? Please fix the broken stuff, before adding cheesy-looking "lightbox" popups for logins and other such pointless crap.

Thanks,

Gordon

Re:Please move along ... nothing to see

[Teancum]

What surprises me here is that this guy didn't bother simply writing to Tesla asking them for the data format? While it has been changing, particularly in regards to the partnership with Toyota, Tesla Motors has typically been quite open about what they are doing and more than willing to work with the after market & car hacker crowd. They certainly are a small enough company that a simple letter (snail-mail) or very well formed e-mail to J.B. Straubel (the engineering head at Tesla and co-founder of the company... arguably having a better claim as co-founder than Elon Musk) simply asking for some of the details. If that approach was tried and failed, then I could see this being a big deal.

Some of the other automobile company, perhaps there would be a point to hacking the data format here, and some automobile manufacturers may have even deliberately obfuscated the data in some way to make hacking the information . But to me the first thing I would do is to simply ask for the format in the first place, and being a customer owning one of these vehicles is likely going to be enough to give credibility to the request. Somebody developing an after-market data massager is likely going to get some support too.

Besides, I think this data has been hacked already or there are documents about the data format floating around in other forums if you really wanted to look. I've heard about some other folks who've hacked into the data format to retrieve information about the light signals (brake lights, turn signals, hazards, etc.) which is contained in the data stream. There is likely much more "out there" if you simply asked in the proper forums.

Re:Please move along ... nothing to see

[Pharmboy]

>>Isn't that statement redundant? All python code is simplistic and ugly.

That's true of any very high-level language, like Python, Ruby, Haskell, Pascal or C.

This is why I only program in Perl.

Re:woohooo

[DrInequality]

Most places you want to drive, top speeds are greater than speed limits so acceleration is more significant.

author is not the author

[Anonymous Coward]

all he did was read some posts in a forum, find someone's work on reverse engineering the format, and the made a python version. wow.

Re:author is not the author

[Anonymous Coward]

Yeah, consider me totally fucking underwhelmed. "So I Googled how to get the data off the car, then I Googled how to read the data, then I wrote a program to read the data! Aren't I great?!"

I'd love to mess around

[Compaqt]

with a Tesla, too.

But then it would mean having to go outside.

Choices, choices ...

Re:woohooo

[by (1706743)]

Most places you want to drive, top speeds are greater than speed limits so acceleration is more significant.

You've never wanted to drive on the Bonneville salt flats?

Re:woohooo

[Jake Griffin]

Then he shouldn't have said "speed", but "rate of change of speed with respect to time" or "dSpeed/dt". ;-)

Wow

[Jethro]

I'm surprised took so long, given the immense popularity of that car.

Re:Wow

[im_thatoneguy]

It didn't take this long. There was already a proof of concept windows binary that decoded it. It's just now been done in Python--messier.

Slashdot summary wrong, film at 11

[dch24]

The summary is wrong, but still, s1axter was the first to publish code that could read the log format.

It's not completely reverse engineered yet. And he used other guys' work.

That's pretty normal for the reversing world. Queue a soviet russia joke here.

Re:Slashdot summary wrong, film at 11

[obarel]

In soviet Russia the summary is right.

Re:Slashdot summary wrong, film at 11

[Anonymous Coward]

In Soviet Russia, the joke laughs at you...

Re:Slashdot summary wrong, film at 11

[Anonymous Coward]

In Soviet Russia, they know the difference between "queue" and "cue"?

Re:woohooo

[haruchai]

That's why I pointed out "from a standing start". Not that the top speed is "electronically limited" - I'm sure I'm not alone in wondering just how fast it would be unlocked.

Its 1/4 mile times are pretty fearsome, too.

And for the price you're not giving up too much versus a Porsche 911, except for top speed ( significant difference ) and range ( if you plan to go more than 200 miles round-trip )

What Porsche do you have?

Re:woohooo

[OldeTimeGeek]

I took my Mustang out there about ten years ago. It was fun but I never really got the salt out of all of the places it found a way into.
Protip: Don't drive there in early morning except in high summer - the salt is wet and sticks like nothing you've ever seen before.

It also contains...

[wholestrawpenny]

..a real-time man-bear-pig tracking network formed by the immense fleet of Tesla vehicles. They expect to have the creature's location pinpointed by 2015. Did you really think Al Gore was involved because of the green initiative?

Re:woohooo

[The Great Pretender]

My 1985 hover car idles at 125 mph, while I ignore this story to brag about how cool I am

Re:woohooo

[by (1706743)]

1977 911S (2.7L) Targa, 340,000+ miles =)

I do wonder what the Tesla could do sans a governor, but since it only has one forward gear, I imagine it might get a little upset in the ol' rev department...

Re:woohooo

[Anonymous Coward]

My econobox can hit 125 mph, too, but that's not the point. It tops out at 125 mph because it only has a single gear. They could have equipped it with more gears and gotten a higher top speed, but they didn't feel that speeds over 125 mph were a practical enough concern that they should give up the advantages they gained by have one gear.

The Tesla can do a quarter mile in ~12.6sec at ~105mph. It's pretty clear that it doesn't run out of oomph at 125mph, it's just not designed to run any faster than that. It has plenty of punch right up through 124 mph.

Re:woohooo

[SimonTheSoundMan]

Never been to the UK during winter I take it?

Re:woohooo

[TooMuchToDo]

I'd never take my Roadster to the salt flats. If I'm going to the flats, I'm going to break a ground speed record. Anything less is a waste of time.

Re:woohooo

[Teancum]

The Roadster has a governor? I've never heard of such a thing. The main deal is that the RPMs in the engine start getting to insane levels turning the engine + drive train into a huge flywheel which takes increasingly larger amounts of energy (it increases geometrically, not linearly) to spin even faster. If that is a governor, then so be it, but removing THAT governor is simply removing the engine altogether.

The limiting factor is the current draw from the battery pack. Expand the battery pack, and you might go faster, but at the expense of killing your acceleration time due to additional weight.

I suppose you could hook up a Mr. Fusion or some other massive energy source that could kick the car into overdrive, but once you get past 88 mph you would be looking at temporal displacement when that happens too.

Re:woohooo

[haruchai]

Impressive. How many rebuilds? What sort of shape is it in?

another lame timothy article

[Anonymous Coward]

another lame timothy article

Re:woohooo

[Anonymous Coward]

That's a fast quarter mile, but I don't understand how that supports your conclusion about the top speed.

I used to have a motorcycle that could do a quarter mile just slightly faster than the Tesla (12.1 seconds @ 109 mph), but the bike's top speed was just slightly lower than the Tesla at 118 mph.

Re:woohooo

[Urza9814]

But is that limited by horsepower or a governor? Makes a big difference. Plus, 125MPH is still 45MPH faster than the legal speed limit anywhere in the US. Not that that means a damn thing. But anyway, as long as it's not a horsepower limit...if you're spending that kind of money and plan on going that fast, I'm sure you can find a way to get it reprogrammed. And since it's right at 125MPH, I'd imagine it's a programmed limit and they're using U or H rated tires. Could be wrong though.

Re:woohooo

[Anonymous Coward]

That's cool. My 1985 Delorean can only go up to 88mph. It punches a fabric of space-time continuum past that speed. :-(

Re:woohooo

[Dare nMc]

In electric motors, current creates torque; voltage is speed. To up the speed you would have to up the voltage. However it will be limited by the insulation between windings, exceed that voltage and it will arc through the insulation and the motor will melt beyond repair. Happens to electric drive trucks down hills; speed past supply voltage motors become generators, keep going self induced meltdown. Add insulation, efficiency goes down, motor gets bigger... Torque has similar issues, More current for torque needs larger diameter windings or losses and heat increase, heavier motor... Basically if the motor has spare capacity, it is heavier than needed and room for efficiency and cost improvements (doubtful.)

Re:woohooo

[Teancum]

It should be noted that the Tesla engine uses an alternating current motor instead of a direct current motor. In fact, that is why it is called "Tesla Motors" in in part that the original patent for the engine design being used on the Roadster was filed by none other than Nikola Tesla himself, where the RPMs on the motor are being regulated by the voltage frequency. It really is some cool tech, and part of their "secret sauce" that distinguishes what Tesla Motors is doing from some of the other electric vehicle manufacturers.

You are correct that there are a whole bunch of compromises that end up having to be made when trying to tweak performance on an electric automobile, which is why I find it annoying when I see people ripping on the Roadster when they don't have a clue about what went into its performance.

Going 120 mph max with a 0-60 in roughly 4 seconds certainly isn't the performance envelope of a golf cart.

Re:woohooo

[Dahamma]

Yeah, salted roads is nothing new in the US, either ;)

120 SQ KM OF SALT on the other hand, is interesting...

Re:woohooo

[Anonymous Coward]

Well, I have to say "fast" is a pretty vague term... you could just as well apply it to a lap time as maximum speed.

Though in the end it is fairly useless on the track as well - a late model C2S (which probably cost 3/4 the price) beat it around the (relatively slow) Top Gear track, and while you wait 4h to recharge it after ~50 miles you can refuel the 911 in a couple minutes. So on a reasonably fast track you get 45 minutes of driving and then are done for the afternoon.

Re:Why not just plug into the ODB II port?

[RMH101]

"The Tesla has a gas engine "
For fuck's sake...

Re:woohooo

[Anonymous Coward]

There's only one gear, and 125 mph is 13,500 RPM, which is considered redline.

You're probably right that it's limited by software that can be hacked around, but it's not like a normal car where you might hit the governer at 4,000 RPM with a 7,000 RPM redline.

Who knows if the 13,500 RPM redline is arbitrary, but as rotation speed goes up, stress on the engine goes up geometrically. Bypassing the software and revving it to 15,000 RPM could very well damage it. Or it could be fine, but are you willing to risk over-revving a $100K car?

Only in a stright line

[mjwalshe]

Take a look at the comparison of the Tesla vs the Elise that TG did the Tesla handled like a pig round the corners

Re:Why not just plug into the ODB II port?

[Teancum]

Amen to that, brother! Sometimes people don't have a clue for what they are talking about, and this one takes the cake!

Re:woohooo

[Cytotoxic]

Going 120 mph max with a 0-60 in roughly 4 seconds certainly isn't the performance envelope of a golf cart.

This is true, but after driving a roadster one of the ways I described the experience was that it was like driving the world's fastest golf cart. The mindblowingly instantaneous acceleration is only encountered in an electric, and the foot-off-accelerator instantaneous deceleration of the electric takes some getting used to. Take your foot off the "gas" in a Tesla and you don't coast like you do in a 4-door sedan, you decelerate fairly hard. All-in-all I highly recommend taking the Tesla for a spin. It will induce giggles like a carnival ride.

Re:woohooo

[karnal]

Sounds similar to a motorcycle - the deceleration on dropping the throttle to idle is a lot different than a car.

Re:woohooo

[tibit]

The voltage limits in a typical electric drive system are there due to the battery voltage, not due to motor's insulation. Any motor worth its salt should have its insulation system survive 2-3x overvoltage without damage. Ergo -- no way to "melt" an electric truck motor by going fast downhill, what you may well kill is the output switches (half-H bridge triad) of the power supply.

ECU?

[Thelasko]

What use does an electric car have for an Engine Control Unit? There is no engine to control!

Fine, call an engine a motor (I don't), but a motor is not an engine.

Re:ECU?

[geekoid]

An engine is a machine designed to convert energy into useful mechanical motion.

Re:ECU?

[Thelasko]

An engine is a machine designed to convert energy into useful mechanical motion.

An engine is a machine designed to convert heat into useful mechanical motion.

Fixed it for ya!

Re:ECU?

[Thelasko]

...and no, I don't care about what an encyclopedia written by the unwashed masses has to say on the topic. My Thermodynamics books say otherwise.

Re:ECU?

[Teancum]

An engine is a machine designed to convert energy into useful mechanical motion.

An engine is a machine designed to convert heat into useful mechanical motion.

Fixed it for ya!

I suppose that is true even for an electric motor, although the heat conversion is filters and perhaps even delayed a bit, even if it is solar powered, in which case the heat energy is even more remote and due to incandescence on another astronomical body. But no matter how removed from that heat, you are pretty much spot on correct.

Of course you could also say that an engine is designed to convert nuclear fusion into useful mechanical motion, as almost all forms of energy come from nuclear fusion at some point or another either currently or from the distant past.

Re:woohooo

[SleazyRidr]

Wasn't there supposed to be a gearbox on the initial model, but they couldn't find one that would work with the torque?

That would give you a higher top speed without sacrificing your acceleration (much). My source for this is Top Gear, so if I'm completely off the mark please accept my apologies.

Re:woohooo

[Dare nMc]

safe to say, you haven't seen what I have. Many of these trucks are designed for 20 MPH top speed, especially the DC drive, operator wants to send one of them over the edge, just head down the hill with the system off kick it in about 30 MPH, and it shoots flames about 20' out from the wheel motors (have to see if I can find one on youtube, it is impressively bad.) Granted the DC drive starts with the brushes, once it carbon arcs them they start the cycle and they will inevitably start melting the insulation on the motor. Some AC drive have a little more margin, but not the 2-3* you claim, not worth the reduced efficiency and greater motor size to have more insulation than needed.

Re:woohooo

[Teancum]

The gearbox is even still there, but modified for only one set of transmission gears. Yes, the Roadster was supposed to have at least two sets of gears so it could in theory reach higher speeds, and I'm not entirely sure what the original top speed was supposed to be, but I think it was higher than the current 125 mph. Since this is well above the legal speed limit for any stretch of highway in America, it wasn't seen as a pressing concern for a production automobile trying to meet ordinary consumer demand.

This gearbox was also the major hang-up that nearly killed the Roadster and almost took out Telsa Motors as a company. It was also the final straw that got Martin Eberhard fired and kicked out of the company when the whole transmission endeavor was at least considered to be grossly mishandled by the Tesla board of directors. Lawsuits flew around for a while afterward and it got pretty ugly.

This blog entry by J.D. Straubel goes into the harry details about how the transmission and power train work, what some of the compromises they had to make to get it to work, and how it was brought "in-house" after being disasterously outsourced.

Re:woohooo

[tibit]

I think you are entirely misdiagnosing the problem.

The motors generate a back-EMF simply because they are turning. You don't need to have anything attached them at all. If the intra-winding insulation on the motors were to fail due to overvoltage, you'd achieve that without anything attached to the motors -- spin them fast enough, insulation breaks down, windings short together and start dissipating mucho power, flames shoot out. Try it out: disconnect the motors, hook the output to a voltmeter (via a fuse!, you don't want a short in the voltmeter to blow in your face), run down the hill (assuming there's a separate brake system available).

Since, as you claim, you have to "kick it [the drive electronics] in" at about 30MPH for the flames to shoot, it's not due to overvoltage *in the motors*. Likely there is an overvoltage crowbar in the drive electronics that shorts the motors temporarily when the voltage is too high. This causes huge power dissipation and self destruction of the motors. Any insulation breakdown is a secondary effect from overheating, not the primary cause IMHO.

I reiterate that a typical electrical motor's insulation system should withstand 2-3x overvoltage with no adverse effects. The way you test it is by applying a test voltage from a hipot tester between the windings and the case.

Even if you get insulation breakdowns, the common thing that would break down in a properly designed and manufactured motor is the winding-to-case insulation. Any drive system worth its salt should detect such a condition and disconnect itself from the motor -- thus no damage done. In a brushed motor, the commutator or sliprings may well break down first -- that's pole-to-pole and not pole-to-case

The only way an overvoltage-due-to-overspeed on an electric motor will damage *insulation* is when you have very poorly designed windings. Perhaps the motors were rewound by someone without a clue?

I'd expect most electric motors to get mechanical damage from overrevving way before there's any electrical damage in the motor itself. Perhaps a dirty commutator or dirty sliprings will break down and catch fire, maybe, but I'd think that's rare if the motor works well at rated voltage. Now if the drive system decides to fry the motor, like what you're telling me implies, that's another story -- just don't blame winding insulation for that.

Re:woohooo

[yurtinus]

That is, when you could actually get it to start.

Re:woohooo

[SleazyRidr]

Cool, thanks for the link!

Re:woohooo

[Anonymous Coward]

If it's not my car (and it wouldn't be) ? Absolutely! I'd also try a 1g turn in those "new" BFG tires ....

Re:woohooo

[badkarmadayaccount]

Why would insulation degrade efficiency?

Re:woohooo

[THEbwana]

Something like this? http://en.wikipedia.org/wiki/Flux_capacitor#Flux_capacitor