A/C and Speed Impact on range

[Elsa]

Hi guys, for a 2.5 hour 155 mile drive how much range would I lose by having the A/C on for an 85 degree day? Also how much range would I lose from the listed 250 mile range if I was going an average speed of 80 miles per hour instead of the base case? Seems like about 40 miles based on the graphs out there does that seem reasonable?

I have a P90d Model X ordered but am considering upgrading to 22 inch wheels. I make a 155 mile drive every summer weekend that I would like to avoid stopping at a supercharger for. Thanks in advance for the help!

 

[X Fan]

Questions: describe elevation characteristics of that 155 mile trip. Rain, snow, cold a possibility?

In a non-PX with smaller wheels & on a flat FL to NC back/forth trip the most I lost was 19.23% in a very windy post tropical storm inclement weather event. Look to others with P characteristics and/or suggest looking at trip logs that have been posted. At a full charge, I don’t see how you wouldn’t make it however.

 

[Aljohn]

Since you don't have the X, you may want to plug the numbers in evtripplanner.com. you will have to use the Model S P85D scenarios. w/ 21" rims. Plug to and from locations, speed (ratio to speed limit), air conditioner temp setting and outside temp., etc. It will be fairly close to what you would experience. Unfortunately, there is no Model X scenarios as yet. However, it will show whether you need the SC stop for the trip.

I have a P90D with 22" rims and had no issue a moderate (65mph) speed, had no issue getting 200 miles on single charge starting with a full charge rated at 250. I run the tire 5lbs over the 40 pound recommendation. 80mph would be problematic -- since your speed would require more watts/mile.

 

[ChadS]

HERE is a thread with detailed numbers...though they are for the Model S, so may have to be adjusted slightly for the X.

As Aljohn mentioned, tools like EVTripPlanner can calculate this in detail. Though it's still best to leave a healthy buffer, because there can be things like sudden rain or headwinds that cause you to use more energy than projected.

 

[SageBrush]

You didn't mention net elevation change or mountain driving that results in brake use.

On level ground you would be fine for most of your drives but wet roads in conjunction with headwinds might force you to slow down or use the SC.

 

[Aljohn]

You didn't mention net elevation change or mountain driving that results in brake use.

On level ground you would be fine for most of your drives but wet roads in conjunction with headwinds might force you to slow down or use the SC.

EV trip planner with the actual to and from locations calculates the elevation changes as part of the scenario's. I considered @Elsa may not have wanted to disclose those in the public forum.

 

[Elsa]

Thanks for all the replies, very helpful! Elevation is flat and not much wind generally expected, but I would prefer the option to drive 75-80 the whole way through if no traffic. It seems like it would be just about possible to do with 22" wheels (25% reduction in range from higher speed + 12.5% reduction from the wheels) but the stress of cutting it close doesn't seem to justify the benefits of the bigger wheels. I think will stick with the 20".

 

[Rocky_H]

Thanks for all the replies, very helpful! Elevation is flat and not much wind generally expected, but I would prefer the option to drive 75-80 the whole way through if no traffic. It seems like it would be just about possible to do with 22" wheels (25% reduction in range from higher speed + 12.5% reduction from the wheels) but the stress of cutting it close doesn't seem to justify the benefits of the bigger wheels. I think will stick with the 20".

I know some people are like “I want to go with the FLOW!” and “I didn’t pay $$$$$ for this car to go slowly!!”, etc. But do keep in mind that it doesn’t have to be all or nothing, with either 65 or 80 mph. Wind resistance is going up pretty steeply at those levels near 80. Even going around 73 to 75 mph saves a LOT of energy, versus 80.

 

[timk225]

I have a hard time believing that rim diameter makes any significant difference in mileage. The overall diameter of the tire will be very close, between the different tire / rim combos.

 

[Rocky_H]

I have a hard time believing that rim diameter makes any significant difference in mileage. The overall diameter of the tire will be very close, between the different tire / rim combos.

It’s not a factor related to the overall diameter or circumference. It’s about response to bumps and vibration. With the big rims and low profile tires (rubber band-like), bumps hit the body of the car more, which is sucking a little bit of energy from the forward motion of the car. With less metal and more rubber, for tires with a taller sidewall, they have more flex, and can roll over bumps more easily, and not sucking as much energy into jarring the car body.