Tesla Semi on Steep Grades (Napkin Physics)

[meitschis]

With two kids successfully launched to STEM college, I am running out of high school physics problem. So I did this

Tesla Semi vs Eisenhower Pass - kiloWatt.page

The Tesla Semi Truck can keep steady speed down any interstate at any legal speed. It can also slow down the truck on that hill. The brakes will be cool at the bottom.

kilowatt.page

TL;DR: The Semi can keep steady speed down any interstate at any legal speed. It can also slow down the truck on that hill. The brakes will be cool at the bottom.

 

[ThomasD]

Can you gain as much range going downhill as you lost going uphill? I'm curious because if you were towing a load in very hilly terrain like West Virginia wouldn't the range loss be canceled out by the downhill sections

 

[MP3Mike]

Can you gain as much range going downhill as you lost going uphill? I'm curious because if you were towing a load in very hilly terrain like West Virginia wouldn't the range loss be canceled out by the downhill sections

No, because there are losses involved in everything. You might get 80-90% back on the way down.

 

[TunaBug]

Can you gain as much range going downhill as you lost going uphill? I'm curious because if you were towing a load in very hilly terrain like West Virginia wouldn't the range loss be canceled out by the downhill sections

You’re asking if they built a perpetual motion machine.

 

[TunaBug]

With two kids successfully launched to STEM college, I am running out of high school physics problem. So I did this

Tesla Semi vs Eisenhower Pass - kiloWatt.page

The Tesla Semi Truck can keep steady speed down any interstate at any legal speed. It can also slow down the truck on that hill. The brakes will be cool at the bottom.

kilowatt.page

TL;DR: The Semi can keep steady speed down any interstate at any legal speed. It can also slow down the truck on that hill. The brakes will be cool at the bottom.

Cool write up. Thanks for showing the use of Google for more than trivial arithmetic and dealing with units, too! I didn’t know you could do that now.

I am skeptical of your 90% efficiency for regen, but I don’t know enough about that to provide a better number (or links).

 

[meitschis]

Cool write up. Thanks for showing the use of Google for more than trivial arithmetic and dealing with units, too! I didn’t know you could do that now.

I am skeptical of your 90% efficiency for regen, but I don’t know enough about that to provide a better number (or links).

I am working on another writeup.

But there TL;DR is that on the 500 mile graph there was pretty much no impact from the Grapevine and the other elevation. That route had ~16,000 ft total elevation.

 

[meitschis]

Cool write up. Thanks for showing the use of Google for more than trivial arithmetic and dealing with units, too! I didn’t know you could do that now.

I am skeptical of your 90% efficiency for regen, but I don’t know enough about that to provide a better number (or links).

I am now claiming 95% roundtrip.

Tesla Semi Round Trip Efficiency is 95% on Mountain Passes (Napkin Physics)

Here is more, and this is so insane that I am still looking for the flaw :-) https://kilowatt.page/tesla-semi-regen-roundtrip-efficiency-is-95-percent/ Based on the 500 mile energy graph, the Semi regen efficiency is insane. Roundtrip efficiency is ~95%, and one way is ~97%. Battery size is...

teslamotorsclub.com

I really hope that my posts age well, but I am skeptical myself