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New Launch Mode - firmware 2.9.40

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not sure I see the point of this launch mode sequence procedure..... why not just stomp on the accelerator and go... it's not like the car will pre-load like a regular ICE car...

I just hope it's quicker/faster and runs 10's!

of course I'm out of town and far away from my P90DL so I can't test until tomorrow night, assuming my car has the update waiting...
 
Oh that is too funny.

Glad I'm not the only one that got a kick out of this.

Pretty sure at best "Launch Mode" will shave the minuscule time it takes to fully depress the go pedal. Just a theory, but, I don't see how it would improve beyond that. There is no kinetic energy built up for launch in an EV like it would for an ICE with launch control...
 
Glad I'm not the only one that got a kick out of this.

Pretty sure at best "Launch Mode" will shave the minuscule time it takes to fully depress the go pedal. Just a theory, but, I don't see how it would improve beyond that. There is no kinetic energy built up for launch in an EV like it would for an ICE with launch control...
But 200ms is minuscule... From a standstill the inverter output is at the lowest possible frequency, it probably takes a few cycles to get to full power, the time is probably significant compared to 200ms. Plus probably 100ms saved from getting the accelerator to the floor.
 
But 200ms is minuscule... From a standstill the inverter output is at the lowest possible frequency, it probably takes a few cycles to get to full power, the time is probably significant compared to 200ms. Plus probably 100ms saved from getting the accelerator to the floor.

Guess we'll see when some vbox results come in.

I'm betting the total difference is way less than 100 ms.
 
Glad I'm not the only one that got a kick out of this.

Pretty sure at best "Launch Mode" will shave the minuscule time it takes to fully depress the go pedal. Just a theory, but, I don't see how it would improve beyond that. There is no kinetic energy built up for launch in an EV like it would for an ICE with launch control...

I disagree. I can see at least 4 places in the car where this will save time.

1. Go pedal travel time. This is replaced by brake pedal release time instead, thus the only time saved will be the difference between the two. Probably the smallest gain.

2. Torque is already built up in the axles. The axles elastically deform under high torque, and it takes time for that torque wind-up to build in the axle before the torque being produced at the induction motor's rotor can reach the wheels. The launch mode will allow this torque wind-up to be pre-loaded, resulting in all torque produced at the induction motor rotor to already be transmitted to the wheel hubs.

3. Reduction gear lash is already taken up. This is not only the small clearances between gear teeth, but also torque deformation in the gears and splines.

4. I think this one is probably the most important. You have already established magnetic fields in the induction motor stator and rotor. The stator and rotor are magnetically permeable cores, and therefore have an inductance. Building current in them takes time because back-EMF resists the change in current. By pre-establishing the stator's rotating magnetic field and the induced rotor currents, you bypass this build-up time.

This is also why you only have 4 seconds to launch the car. The power going into the motor that is pre-loading everything is being 100% wasted as heat until the launch occurs, so you are heating the stator and the rotor pretty heavily. After 4 seconds, the temperature will have built up and you need to either launch or stop current flow.

We need to see an instrument cluster view of a launch mode with the Energy App displayed. I'd like to see how much power is being sent to the motors before the brake pedal is released.
 
I disagree. I can see at least 4 places in the car where this will save time.

1. Go pedal travel time. This is replaced by brake pedal release time instead, thus the only time saved will be the difference between the two. Probably the smallest gain.

2. Torque is already built up in the axles. The axles elastically deform under high torque, and it takes time for that torque wind-up to build in the axle before the torque being produced at the induction motor's rotor can reach the wheels. The launch mode will allow this torque wind-up to be pre-loaded, resulting in all torque produced at the induction motor rotor to already be transmitted to the wheel hubs.

3. Reduction gear lash is already taken up. This is not only the small clearances between gear teeth, but also torque deformation in the gears and splines.

4. I think this one is probably the most important. You have already established magnetic fields in the induction motor stator and rotor. The stator and rotor are magnetically permeable cores, and therefore have an inductance. Building current in them takes time because back-EMF resists the change in current. By pre-establishing the stator's rotating magnetic field and the induced rotor currents, you bypass this build-up time.

This is also why you only have 4 seconds to launch the car. The power going into the motor that is pre-loading everything is being 100% wasted as heat until the launch occurs, so you are heating the stator and the rotor pretty heavily. After 4 seconds, the temperature will have built up and you need to either launch or stop current flow.

We need to see an instrument cluster view of a launch mode with the Energy App displayed. I'd like to see how much power is being sent to the motors before the brake pedal is released.

Everything mentioned here in total is not going to result in a significant difference in times like 0-60 times and 1/4 mile times.

I'm going to stick with my prediction above that the total difference with and without "launch mode" is going to be 100ms or less. I hope I'm wrong, but I really don't see how additional time can be saved beyond that. Basically this will be within a reasonable margin of error on vbox results and will be pretty hard to nail down any real difference.

Additionally, with respect to point 1, there is no brake pedal travel time involved when measuring performance. The time it takes for the go pedal to get from 0 to 100% is a positive amount without launch mode, and this a delay. The time it takes for the car to initiate launch after the brake pedal has been fully released is going to be pretty much zero. It's not going to start the launch during pedal travel like it does with a normal launch mashing the go pedal.

For point 2, I'd love to see some engineering estimates on this. I highly doubt there is significant elasticity in the drive axles for this to have any measurable effect whatsoever.

For point 3, this doesn't effect launch times since the car wont move until this slack is closed anyway. Reaction times maybe by a few ms, but not 0-60 or 1/4 mile times.

For point 4, this is probably the only place besides point 1 where there can be a gain, and it's going to be minuscule... like, double digit millisecond minuscule at best. Plus, Tesla has already acknowledged that they can sleep and wake the motors with imperceptible precision.
 
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I've probably only tried it 4-5 times but I'm going to guess maximum benefit from this is going to be limited by traction. Given I'm on 19in tires with 28k miles but when launched there is an immediate tire slippage. Then you feel traction control kick in and then the power pick back up. I believe the improvement would be very significant if they would back off on the traction control a little and allow the tires to just spin a some.
 
The car launches a lot harder now. The pedal dance is also incredibly easy to do. Simply press the brake with your left foot. Floor then release then floor (can be done very quickly) then side step the brake and she goes. There is absolutely no wait and you can do the sequence as fast as you can press and release the pedals because the system does not have to do (much of any) spooling up. You do feel the car load up against the brakes when you floor it the second time before side stepping the brake. I tried not to leave it like that very long and found the car launched just as hard even when doing the sequence very quickly. Put differently, the pre-loading against the brakes happens as fast as you can get the throttle to the floor and side step the brake.

Very nicely done Tesla.
 
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