News tidbits from latest Tesla blog

[TEG]

Tesla Motors - hear

• "First gear was not available (on VP10)" (locked out for some reason)
• "We have been testing a few configurations of the regen braking profile."
• "Driver adjustable regen is a possibility in the future."
• "VP10 ... has been updated to include a creep feature.
  Creep has been added as a safety feature to ensure that drivers do not leave the car on and in gear when they exit the vehicle."
• "driving the car aggressively for awhile can increase the temperature of the electric motor to a point where the car’s firmware modestly limits the power output to keep the temperature from rising farther. "
  "The production motor will have improved airflow to aid cooling."

 

[tonybelding]

Tesla Motors - hear
"First gear was not available (on VP10)" (locked out for some reason)

Pure speculation on my part, but they may not have had the new transmission installed in VP9 in time for that test drive. errr. . . VP 10. . . whichever. . .

 

[TEG]

I thought the problems with 1st gear were only with the EPs.

I think Martin said that they switched transmissions because the original supplier couldn't provide enough of them, but perhaps that was the "spin control" version of the story.

 

[MDR]

Pure speculation on my part, but they may not have had the new transmission installed in VP9 in time for that test drive. errr. . . VP 10. . . whichever. . .

Thats right, from what I was told, VP9 & VP10 for sure and possibly all or some of the other VPs are fitted with the old transmission. This was a surprise to me as somehow I assumed all the VPs had the new model.

 

[WarpedOne]

I guess the peculiarities of high rpm high power eletric engine is quite a chalenge for transmission suppliers. I'm afraid TM hadn't gone through all the problems yet.

 

[DDB]

Any owners hear whether deliveries will in fact be on target for October? It's been quiet from TM of late--hopefully because they're on the production line.

 

[malcolm]

Martin's post on the new transmission in EP5 was posted on the 18th of August, so it is entirely possible that the VPs are without this upgrade. But given that Tesla are already on record stating that the production run for customer cars will start slowly, I'm sure that there is ample time to make these changes.

I also speculated that heat may be the issue, but I've changed my mind. The motor is water cooled and the EPs have been put through endless thermal tests. Given Tesla's engineering focus on ESS cooling, I can't imagine that the motor hasn't been given the same level of anaylsis.

Since the VPs are the press review machines, the motors/transmissions will need to be swapped out; again, not an issue - the San Carlos centre was filmed doing this sort of work ages ago:

MSN video

 

[malcolm]

"The production motor will have improved airflow to aid cooling."

I'm assuming that this means improved air flow to the motor's radiator or the motor or both. Possibly the upgraded transmission has changed the air flow around the motor and/or other key thermal components.

I'm guessing that the profile of various ducts / vents are being tweaked as we speak. Pure speculation on my part, but maybe the underside of the trunk lid will have to be fitted with some sort of cowling thing to focus more air flow around the motor when the trunk is closed?

 

[TEG]

The motor is water cooled

No - the motor is air cooled.

My guess is that the torque & RPMs are what is hard for the transmission.
In particular the Tesla has no flywheel so the transmission could be exposed to sudden changes in torque without any "buffer".

I think improved cooling for their motor would be better ducting or perhaps a fan that blows air onto the motor.

 

[vfx]

"Creep has been added as a safety feature to ensure that drivers do not leave the car on and in gear when they exit the vehicle."

I don't get it.

You would rather have the car moving when you exit than not? Why is it a bad thing to leave it in gear and leave the car. By habit many will do that to prevent rollaway in a ICE car with a manual transmission.

What happens with an automatic transmission ICE car when you get out with it left in gear?

Seriously, I'm not at all for a car that mis-grammatically says "Your door is a jar", but a door open light and or beep when it's left in gear seems better than the entire car moving!

---------------------------


BTW maybe if the car has a beeping sound when you open the door while is gear, maybe when you need to alert people in the way you are coming then you can crack open the door a bit for a friendly alert tone instead of obnoxiously honking the horn at them.

 

[tonybelding]

You would rather have the car moving when you exit than not? Why is it a bad thing to leave it in gear and leave the car. By habit many will do that to prevent rollaway in a ICE car with a manual transmission.

I think you've hit on the problem right there. If you leave an ICE car parked and in gear, the internal friction of the engine prevents it from rolling away. The electric motor has no such internal resistance. The only secure way to park it is with the hand brake engaged. This will require a change in habits for quite a few people.

I'm not one of them. Personally, I don't like leaving my car in gear. I always park it in neutral with the hand brake engaged. When I had it serviced at the dealership, the technician parked it in front when he was done with it. I hopped in and started to crank the engine, and the car jerked forwards! He'd left it in first. That startled and embarrassed me.

It has led to more embarrassment for some other people:

http://video.google.com/videoplay?docid=9067676890384018570

 

[vfx]

Driving safety experts say to prevent runaway cars on hills that a manual transmission car should be put in gear, tires turned and emergency braked engaged.

Transmission experts say cars parked on hills should not be left in gear because of the strain put on the gear teeth and components of the gearbox.

 

[mt2]

When Stephen Casner wrote the blog entry he so strongly dislikes the creep "feature" he wrote a whole paragraph commending Tesla on getting rid of it. That should tell you something right there. I, personally, can't stand it in my ICE - and I take it most people here can't either. If it's a safety issue, I echo the idea that a 'ding' and a dashboard light are all that's needed.

I feel a bit uncomfortable commenting in this thread since I intend to own a WhiteStar rather than the Roadster. But adding the creep seems so anti-Tesla I just had to comment.

 

[TEG]

Tesla is stuck in the unfortunate position of having to make their vehicles act like ICE counterparts. This is in part because drivers are used to certain behaviors, and in part because safety regulations are designed around ICE vehicles.

 

[Takumi]

Can't they just make it creep by default with the option to turn it off?

 

[tonybelding]

When Stephen Casner wrote the blog entry he so strongly dislikes the creep "feature" he wrote a whole paragraph commending Tesla on getting rid of it. That should tell you something right there. I, personally, can't stand it in my ICE - and I take it most people here can't either. If it's a safety issue, I echo the idea that a 'ding' and a dashboard light are all that's needed.

I have a hard time getting "worked up" over this issue.

The shifter knob is always right there at hand. It should take only a moment to put the car in neutral. I habitually put my ICE into neutral when I stop it, just because I don't like sitting with my foot on the clutch.

If you are stopped at a red light, you're going to have your foot on the brake anyhow, right? So it's not an issue there.

One could argue that it would be more elegant, or more true to the EV concept, to drop the creep and come up with some other sort of warning bell or safety switch in the door or something. . . But I can't see how it's any Big Deal, either way.

 

[Brent]

In defense of creep:

1) At stoplights, in left hand turn lanes, and in slow traffic, it forces drivers to keep their feet on or near the brakes, helping prevent worse damage to the front if rear ended;

2) It's somewhat easier to manoeuvre the car at very low speeds by brake alone, rather than switching between the brake and accelerator (although perhaps regen on the accelerator might change the equation).

 

[TEG]

My wife (coming from conventional automatics) loves how her Highlander hybrid creeps very slowly and smoothly on electric power alone. (None of the Rav4EV lumpiness that Stephen Castner described. There is apparently something different about the permanent magnet motor arrangement in the new Hybrids compared to the old Rav4EV). She doesn't, however, like the way her Hybrid highlander can roll backwards on hills unless you give it a lot of go pedal, or stay on the brakes.

This is another area that hasn't been discussed much... "Hill holding". People used to manual trans cars are used to roll back. People with autos tend to want the car never to roll backwards unless it is in neutral or reverse. I wonder about the driving dynamics of the Tesla roadster going from stop-sign to stop-sign on some of the steep hills in San Francisco. The "creep factor" could come into play there.

 

[Brent]

This is another area that hasn't been discussed much... "Hill holding".

I asked TM's Aaron about that when the car came to Beverly Hills last June. He said the car freewheels, such that it will roll backwards on hills.

I'm not so keen on such behavior. Unless I'm missing something, I really can't think of any performance or safety reason why the car should be allowed to have this "feature." If anything, it's rather annoying to have to get one's foot over to the accelerator quickly (and too often, imprecisely) to avoid rolling into the too-close driver behind.