At what speed can I go 318 miles (Rapid City to Billings)?

[johnnyS]

I would not try that far without having a couple of charging options along the way. Ideally having a place to charge about 200-220 into the trip would be good. At that point you will know how you are doing and can estimate how much charge to add. The new software will help on a trip like this. I consider anything over 200 miles long for my S85. It may be fine on paper, but the day of the trip there may be wind or rain. I found it interesting at a Tesla meet up that most of the experienced owners who have been on road trips have come close to running out of a charge.

 

[bevguy]

It should be pointed out that due to tire and drivetrain drag you get only minimal range extension below 40 to 45 mph. Aside from weather and altitude change, a big factor is how carefully you can accelerate and decelerate whether your cruise speed varies. I have found cruse control more reliable than human control on the highway.
If you look hard enough you can usually find some power source on the way, often a RV park. If worse comes to worse even private homes have 120 volt outlets.

 

[Cottonwood]

See latest news at Crowd Funding an HPWC in Sheridan, WY — Casper and Gillette to Possibly Follow - Page 4 and my analysis of this route at Crowd Funding an HPWC in Sheridan, WY — Casper and Gillette to Possibly Follow - Page 5.

Hopefully this will all be a lot easier soon, and then Superchargers will make the route a no brainer.

 

[shadowinstallz]

For 315 miles you want a total of about 360 miles of range--more if the weather is bad--because stuff happens (and it happens to everyone). Somewhere around the 200 mile mark, I'd find an RV park with 50 amp receptacles or a kind Tesla owner (PlugShare) with an HPWC and charge until you have 190 miles of range. There's really no reason to doing anything else. This is how you eliminate range anxiety.

Does OP have dual chargers?

 

[MSEV]

No to dual chargers.