Customer Town Hall Meeting II Information

[donauker]

Here are a few of the items discussed today:

The Roadster motor will not be liquid cooled; it will basically be the current motor with enhanced air cooling (better air flow, fins, etc). The White Star will have a liquid cooled motor.

The new “transmission” actually just a reduction gearbox will have a 8.27:1 ratio which puts it between first gear at 14.3:1 and second gear at 7.4:1 on the 2 speed transmission, albeit rather close to second.

The motor top speed will move up to 14,000 rpm or possibly even higher for a top speed of at least 120 mph or greater.

A new improved PEM will provide more output current to the motor to increase torque output as well as provide full torque output to a slightly higher rpm range. Modeling & some test indicate that they will be able to maintain a 0 to 60 time of 4 seconds (no one was saying under 4 seconds anymore). The difference will be that 0 to 30 will be slower but 30 to 60 will be much quicker. This is due to the new setup maintaining full torque through 60 mph while with the old first gear torque started to fall off past 30 mph due to the higher motor rpm.

Additionally they reiterated that Whitestar development is proceeding and they plan on having a static model to show in the second quarter.

 

[Yanquetino]

Missing something

Thanks, Donauker, for the info. Did the motor discussion occupy the entire meeting? Nothing else came up? Hard to imagine.

I must be missing something, but I don't understand why they would even bother trying to put a water-cooled motor in the Whitestar. It is supposed to be a sedan, not a super sports car like the Roadster. If it could hit 60 in, say, less than 8 seconds, and topped out at 100 mph, most drivers would be happy --and you wouldn't need any cooling. Why add all the extra weight and complication to the design? I say... keep it simple... and the cost down.

 

[donauker]

Liquid cooling is not needed for short duration peak acceleration it is needed for longer duration high load. The Whitstar will be a much larger & heavier vehicle. Think 4 or 5 passengers and bags climbing long grades.

 

[stopcrazypp]

Based on what I've seen here and at other blogs, this town hall meeting II basically confirmed that the roadster will not be liquid cool, but instead have better air cooling. I suppose it makes sense, as it would probably cost lots of money to switch to a liquid cooled setup this late in the game. What other things were discussed? I know a few of you went to the meeting. Thanks.

 

[TEG]

Based on what I've seen here and at other blogs, this town hall meeting II basically confirmed that the roadster will not be liquid cool, but instead have better air cooling.

This article says: "Tesla is working on a liquid-cooled version"
So, some may have thought the "standard" production version would get water cooling, but it sounds like it is just an idea for a track special, and the Town Hall meeting clarifies it.

 

[tonybelding]

Here's a nice summary:

Tom Saxton

A small but interesting point to me was that Tesla still haven't made a firm decision about when or *where* the WhiteStar will be made. So, it would seem the whole New Mexico deal may be in danger of evaporating.

 

[stopcrazypp]

This article says: "Tesla is working on a liquid-cooled version"
So, some may have thought the "standard" production version would get water cooling, but it sounds like it is just an idea for a track special, and the Town Hall meeting clarifies it.

Yes, I was confused on that point too, as I think Sam from Autobloggreen originally said he was told by Tesla that the standard Roadster would be liquid cooled (he has since corrected to say that he confirmed that there would be more power put through the PEM requiring aggressive cooling and that "That means it will likely need to be liquid cooled." So it seems he is only inferring liquid cooling is what would be used).

BlackbirdHighway (a member here on Tesla Motors Club) commented: "Another correction for a previous Tesla article on this site:

The new plan is NOT to have a liquid cooled motor in the Roadster, but instead to beef up the air cooling, as well as an improved power electronics module (PEM). The new PEM not only provides more juice to the motor, but is also slightly more efficient as well. "

Here's the link to the article: Don't believe everything you read out there, Tesla production date has not slipped again - AutoblogGreen

So I guess it's just some confusion that the Town Hall Meeting II cleared up. Sam himself wrote an article on the track version you mentioned here: Revisiting the Tesla Roadster as a track car: it could happen - AutoblogGreen

I think the autoblog article you have is basically the same one, except reposted on autoblog.

So this meeting basically is another update on what they have planned on the roadster and a reaffirmation that Whitestar development is continuing along. Did they mention how the 2 transmission suppliers fared; is it because they have completely failed that they went with this plan, or did they go with this plan because they thought it was just a better idea? That's something I have been wondering. Also, is this plan set in stone, meaning have they ditched their 2 transmission suppliers, or are they still keeping options open?

 

[siry]

a little bit of clarification - we are no longer simply relying (hoping) that a transmission supplier will deliver us a gearbox. We have been burned twice by this approach and can't put our fate in the hands of a supplier, so we are relying a lot more heavily on our internal powertrain team and other internal resources for development, sourcing and manufacturing of the gearbox. In the town hall meeting, JB told everyone that the design was complete and we were already into prototyping, so this direction was set shortly after the last town hall - so what that means is that we have indeed abandoned the 2-speed design, at least for 2008. It won't make any sense to put big resources behind a 2-speed at this point, except for a few interesting niche projects we might do down the line. Supplementing our internal team is a team from Ricardo Engineering, who have a great deal of experience on high end, demanding gearboxes such as those that were developed for the Bugatti Veyron and the Ford GT. This gives us the added measure of confidence that our design will be sound.

As for Whitestar, Elon firmly stated the we are committed to WhiteStar, that we are well along on the powertrain development, and will be revealing a styling car (non-operational) in the 2nd quarter. Details on our manufacturing plan will be clearer soon, but Elon mentioned in the meeting that we have been pre-qualified on a DOE loan guarantee that could enable us to debt finance the WhiteStar. We were one of a handful of companies considered for this loan guarantee program.

Much much more was shared over the 90 minutes plus of &A and we will post the audio very soon on our website.

 

[tonybelding]

we are no longer simply relying (hoping) that a transmission supplier will deliver us a gearbox. We have been burned twice by this approach and can't put our fate in the hands of a supplier, so we are relying a lot more heavily on our internal powertrain team and other internal resources for development, sourcing and manufacturing of the gearbox.

If you want something done right. . .

 

[Iz]

It's always good to get information directly from the source. Nice work on getting the DOE pre-qualification. Would be curious to know what other (if any) car companies have been considered.

2nd quarter can be as late as June 30 -OR- April 1 :biggrin:

 

[Yanquetino]

Talk about heavy metal

Liquid cooling is not needed for short duration peak acceleration it is needed for longer duration high load. The Whitstar will be a much larger & heavier vehicle. Think 4 or 5 passengers and bags climbing long grades.

Uh... as usual, I must be missing something. Doesn't the RAV4-EV have seating for 4 or 5 passengers, plus bags? I haven't heard of an instance in which their motors have burned up because they lack a water-cooling system, and those lucky drivers have been using them for several years and thousands of miles now. (I sure wish Toyota would simply resurrect that assembly line and install lithium-ion batteries in them. Folks would be lined up to buy them. Duh!)

It might be too early to tell yet, but I haven't heard of a motor overheating in AC Propulsion's eBox either, and it most certainly boasts plenty of seating and room for luggage.

So... I still don't understand why the Whitestar would need anything different.

 

[Kardax]

Uh... as usual, I must be missing something. Doesn't the RAV4-EV have seating for 4 or 5 passengers, plus bags? I haven't heard of an instance in which their motors have burned up because they lack a water-cooling system, and those lucky drivers have been using them for several years and thousands of miles now. (I sure wish Toyota would simply resurrect that assembly line and install lithium-ion batteries in them. Folks would be lined up to buy them. Duh!)

It might be too early to tell yet, but I haven't heard of a motor overheating in AC Propulsion's eBox either, and it most certainly boasts plenty of seating and room for luggage.

So... I still don't understand why the Whitestar would need anything different.

The RAV4 EV does 0 to 60 in like 20 seconds, due to its weak 67ish HP motor. I doubt a fully-loaded RAV4 EV could climb a hill at highway speeds. The limited power output also limits the amount of heat produced, so burning up isn't really a risk.

Presumably Tesla is aiming somewhat higher for their WhiteStar performance.

-Ryan

 

[Yanquetino]

The data aren't in yet

The RAV4 EV does 0 to 60 in like 20 seconds, due to its weak 67ish HP motor. I doubt a fully-loaded RAV4 EV could climb a hill at highway speeds. The limited power output also limits the amount of heat produced, so burning up isn't really a risk.

Presumably Tesla is aiming somewhat higher for their WhiteStar performance.

-Ryan

That might be true. Just don't know. Hey... if there are any RAV4-EV owners out there, speak up! Can you climb a hill at highway speed in it?

And if not... let's not forget that the RAV4-EV was really only a conversion, i.e., with a frame and body as heavy as the ICE model. Couldn't a vehicle designed from the ground up as an EV, with a lighter aluminum frame, carbon fiber body, and better aerodynamics produce acceptable performance without the need of a radiator? That is how I thought the Whitestar would be "aiming somewhat higher."

Come to think of it, if anybody here actually knows how AC Propulsion's eBox is doing when it comes to motor heat, speak up as well! I'd be very interested to know. It is certainly a different animal than the RAV4-EV, since it boasts:

Curb weight: 2970 lbs.
AC induction motor: 120 kW peak, 50 kW continuous
0-60 mph: 7 seconds
Top speed: 95 mph
Range: 120–150 miles
Redline: 13,000 rpm

That sounds pretty good to me! Maybe the range is more modest, but then again I don't think that a radiator will improve that --only more or better batteries.

 

[TedK]

On a side note, I heard at least 2 people ask the same basic question.........When will owners be offered an opportunity to invest in Tesla the company? Presumably at pre-IPO price levels. Elon said he would ask the board and would support it if the board did. I think its entirely fitting that the people who had early faith and plunked down some serious money(and are waiting patiently) were allowed the opportunity.

 

[donauker]

AC induction motor: 120 kW peak, 50 kW continuous

This is exactly the reason they would liquid cool the motor. They do not want this very low continuous power rating.

There are indications that the new motor is more powerful then the current Roadster motor, but using old Roadster numbers it is not hard to see the problem. At peak net power of 185 KW the specs tell us the the motor is 80% efficient. Therefore we need 231.25 KW input x 80% = 185 KW output. This means that 231.25 KW power input - 185 KW power output = 46.25 KW heat generated due to loss. This is over 11 times the heat output of the Roadster cabin heater!

If we assume the higher 90% efficiency at about half power we can determine what the heat generated will be :

102 KW input X 90% = 91.8 KW output
102 KW input - 91.8 KW output = 10.2 KW Heat, still 2.5 times max cabin heat.

If you think this loss is bad try the numbers with a 20% ICE efficiency.

Additionally you may want to do some research into how an AC induction motor works and how this will tend to build up heat in the rotor which is not the kind of item that is easy to put a lot of heat dissipating fins on.

 

[AGR]

Its positive to see Tesla resolve the entire transmission issue in a simple elegant fashion....no transmission and tweaking the motor a bit.

From the early customer roadtests one of the tester who tried to emulate his Porsche probably came close top overheating the motor, its positive to see the motor cooling improved.

Ricardo is an English company that has been around for many years, and does a lot of behind the scenes work for a lot of manufacturers.

Water cooling at this stage is merely an "intellectual discussion" which will not be implemented any time soon on the roadster.

These guys are moving along...

 

[TEG]

...This means that 231.25 KW power input - 185 KW power output = 46.25 KW heat generated due to loss. This is over 11 times the heat output of the Roadster cabin heater!

Umm, Hello!, how about we duct the motor heat output and use it to prime the cabin heat? ICE cars use waste engine heat to heat the cabin, so why not save the traction pack charge and recapture "waste heat". Does the current design just send the eMotor heat into the atmosphere without recapture?

 

[TEG]

The RAV4 EV does 0 to 60 in like 20 seconds, due to its weak 67ish HP motor. I doubt a fully-loaded RAV4 EV could climb a hill at highway speeds. The limited power output also limits the amount of heat produced, so burning up isn't really a risk.
Presumably Tesla is aiming somewhat higher for their WhiteStar performance.
-Ryan

Yeah, although your numbers were a tad exaggerated. I think 0-60 was under 18seconds (still very slow), and owners reported that they did OK climbing hills, but you might be right that 65MPH on a steep hill would be hard to maintain.

I think your point is valid - the Whitestar will have much more lofty performance goals which would mean far more eMotor heat generated.

 

[siry]

Full audio should be available shortly on the Tesla Website

 

[Yanquetino]

Well... I wouldn't complain with those specs!

This is exactly the reason they would liquid cool the motor. They do not want this very low continuous power rating.

Uh... why not? 0-60 in 7 seconds, and top speed of 95 mph isn't good enough for an EV sedan? Again, that seems pretty good to me!

I guess I still don't get it. If AC Propulsion can achieve that level of performance with a conversion, surely a dedicated EV can do even better with a similar motor. Why add more weight and complication with a radiator --and thus a higher price?

By the way, your claim piqued my curiosity, so I asked an RAV4-EV owner, Patricia Lakinsmith, about hill climbing, and this is what she answered:

You are right - the RAV 4 EV would have no trouble with that. In fact, I live in the mountains near the Northern California coast, and have to climb 1800' to get home each night. Before leasing the car I took a friend and the Toyota sales guy (big guy) with me up that route on a test drive, and no problem. My husband drives a Honda Insight, and *that* one seems to struggle, but not the amazing RAV 4 EV.

Of course, Patty's is only one testimony, so if there are other RAV4-EV owners lurking around here in the forum, please add your $.02 worth too, okay?