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What is Range Mode's torque distribution optimization and what are its costs?

What is Range Mode's torque distribution optimization and what are its costs?

P. 91 of the Owner's Manual on Range Mode: "When turned on in a dual motor vehicle, torque distribution
between the motors is optimized to maximize range."

The Controls::Driving::Range Mode info ("i") pop-up says that Range Mode, in addition to reducing HVAC energy usage, "will also distribute torque between the motors to increase range."

The estimable Bjørn Nyland (bnyland) in another thread said, "With dual motors, range mode will reduce consumption by up to 7 % because of torque sleep."

I had overlooked this torque management benefit of range mode until today -- I had previously thought it merely reduced HVAC energy consumption.

What is this optimization? I haven't found where Tesla calls it "torque sleep," but forum posters seem to. Why is it, or some aspect or degree of it, bundled with reducing HVAC energy? What is the trade-off -- why isn't torque optimization on all the time?

And on the HVAC side of Range Mode: Looking ahead to a summer road trip in my 85D with a significant portion in southern Nevada -- hot outside! -- if I turn on Range Mode will I drown in my own perspiration?

NKYTA | 27. Dezember 2015

My understanding is that torque sleep is "always on" and isn't tied to Range Mode. But I have a Classic RWD.

Range Mode limits HVAC use, but even in hotter climes, you should be okay. We did get some tinting in NorCal where it isn't required, but I lived in AZ for five years, so why not? You can't go to 11 on the fan, only to 8.

Whatever else that Range Mode limits isn't fully clear, and I only use it when on longer trips.

BH or TT might know more...

Muzzman1 | 27. Dezember 2015

Torque Sleep "info" differs on the S85 and Dual motor cars. My S85 only talked about limited HVAC power usage when enabled, while my 85D talks about limited power on HVAC as well as torque sleep on the dual motors to only use one motor when other is not needed to save energy.

hammer @OR-US | 27. Dezember 2015

Here is the blog post from Tesla that talks about "torque sleep" https://www.teslamotors.com/blog/driving-range-model-s-family

How this relates to range mode is not addressed directly however there has been ample evidence that range mode does influence torque sleep. One indicator was a bug in the software shortly after implementation, with range mode engaged, shut down the motors completely, oops. Another is that under steady speed the front motor sounds different with range mode off versus on.

Bettyfretz | 27. Dezember 2015

Q: Which drive unit is able to sleep, front or rear?
With the P85D we put the large, rear, drive unit to sleep while cruising. We choose to sleep the rear unit since the new generation small front drive unit is actually more efficient at converting battery DC electricity into mechanical shaft power. So we benefit from using the small, front drive unit more of the time when it can provide all of the torque requested. In the 85D both drive units are the same and we can sleep either unit, front or rear to best optimize efficiency.