Most Efficient Freeway Speed...Is There One?

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powersurge said:
OMG now we are debating drag coefficients!!

The original question was is there a best speed for efficiency.... I say..... Keep it between 50 and 60...
50/60 is probably the slowest realistic speed however I think a little slower would go further.
 
Physics does not change much between a Tesla and a Leaf. Here is the graph for Model S. Peak appears to be around 22mph. So basically the answer is "as slow as you feel comfortable driving".

graph1.jpg


https://www.tesla.com/blog/model-s-efficiency-and-range
 
^^^
Yep. And https://web.archive.org/web/20100721110430/http://www.teslamotors.com/blog/roadster-efficiency-and-range is the Roadster blog entry w/o broken images.
 
LeftieBiker said:
The most efficient speed is something like 17MPH.
Actually, 12mph. Reference: http://www.mynissanleaf.com/viewtopic.php?p=101293

I used that fact once to continue for over a mile after hitting turtle. :eek: I made it to the charger. :cool:

The drivetrain isn't as efficient as a Tesla Model 3, but Nissan has done an excellent job of reducing steady-state consumption, which is why its most efficient speed is so much lower than a Tesla.
 
DougWantsALeaf said:
Any feel for where Nissan is lagging in drive train consumption?

You can replace the drive unit oil (yeah, this car has OIL :D) with a more freeflowing one. This will increase efficiency further.

The stock oil is specced so that it can handle all different operating temperatures, but you can modify this with a high performance oil that is suitable for your climate.

Adds maybe 0.1->0.2 m/kWh efficiency
 
Dala said:
DougWantsALeaf said:
Any feel for where Nissan is lagging in drive train consumption?

You can replace the drive unit oil (yeah, this car has OIL :D) with a more freeflowing one. This will increase efficiency further.

The stock oil is specced so that it can handle all different operating temperatures, but you can modify this with a high performance oil that is suitable for your climate.

Adds maybe 0.1->0.2 m/kWh efficiency

The transmission does not have "OIL". It Takes Red Transmission fluid...
 
SageBrush said:
powersurge said:
Dala said:
The transmission does not have "OIL". It Takes Red Transmission fluid...
Which is made from ... ?

And what's in Tesla's gear boxes for lubrication?

This would seem similar to the dual-motor Model S, which has a ~9.73:1 rear reduction ratio (at least for the "large drive units), and a slightly "taller" gearing for the front motor (~9.34:1). This allows the car to cruise primarily with the front motor operating at a lower RPM range closer to it's efficiency sweet spot.

https://teslamotorsclub.com/tmc/threads/semi-gear-reduction-ratios.103576/

And what's that black round thing on the M3 transfer case like I see attached to my three ICEVs' ICEs?

https://www.youtube.com/watch?v=ANLPPKRwiyQ
 
DougWantsALeaf said:
Any feel for where Nissan is lagging in drive train consumption?
Tesla has created a more efficient motor and inverter. I haven't seen how it compares to other companies, but the new motor/gearbox/inverter combination resulted in an increase in range of a Model S from 335 miles to 370 miles, with no change to the battery pack. Tesla vehicles are also more aerodynamic, which helps efficiency at highway speeds.

But a Tesla will lose 1-2 miles of range per day regardless of use just from system overhead, whereas I've never noticed my Leaf losing anything when parked.
 
garsh said:
DougWantsALeaf said:
Any feel for where Nissan is lagging in drive train consumption?
Tesla has created a more efficient motor and inverter. I haven't seen how it compares to other companies, but the new motor/gearbox/inverter combination resulted in an increase in range of a Model S from 335 miles to 370 miles, with no change to the battery pack. Tesla vehicles are also more aerodynamic, which helps efficiency at highway speeds.
The improvement in the Model S was due to a swap from the old induction motors that were always less efficient overall than the PM used in the LEAF. The new-fangled SRM motors of Tesla are I think as efficient as PM or perhaps more so but not by a huge margin. I'm not sure about the inverter. You can get a feel for drivetrain efficiency by taking the EPA highway numbers (that approximate 65 mph driving) and subtracting Aero and Wheel resistances. I've forgotten how much the AP functions of the Tesla consume.

Tesla Model 3 LR:
1613 Kg
0.009 Tyre RR (assumption)
Frontal Area: 2.34 m*m
Cd: 0.23

At 65 mph (105 kph) it works out to 117 Wh/km (189 Wh/mile)
EPA is 241 Wh/mile (corrected for presumed 12% charging losses)

So the difference is 52 wh/mile of which the drivetrain is the lion's share
----

The Chevy Bolt is 269 Wh/mile EPA of which 232 Wh/mile is Road+Aero
---

The e-tron is 405 Wh/mile of which 260 Wh/mile is road+Aero. That car has major drivetrain issues.
---

I leave the LEAF to you
 
Tesla Model 3 LR:
1613 Kg
0.009 Tyre RR (assumption)
Frontal Area: 2.34 m*m
Cd: 0.23

At 65 mph (105 kph) it works out to 117 Wh/km (189 Wh/mile)
EPA is 241 Wh/mile (corrected for presumed 12% charging losses)

Tesla Like was showing 316 miles range on the 75 kWh battery at 65 or 4.21 miles per KW for the LR. Teslanomics has a couple videos suggesting a bit less (mid to upper 200s), but guessing he was using AC or other power sapping aspects.

So on the highway at 65 mph you are seeing north of 5 miles per KW? (not close to other cars, or things that would give improved drag characteristics) That's pretty impressive.
 
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