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The affect of hills on range

The affect of hills on range

I live in Utah and for me to take any kind of road trip I need to travers some pretty long and steep canyon roads. Does anyone have any information on how to plan out expected range while accounting for the canyons?

gatorj31 | 21 juni 2017

I believe there is a website called EVtrip planner or something that takes hills into account. I also read someones posting about driving up to to mountains. He was surprised it only used an extra ~10% miles (above the estimated miles) to go up the mountain, but then he gained like 8 miles going back down.

Rutrow | 21 juni 2017

What goes up, must come down. Let the spinning wheel fly.

MarylandS85 | 21 juni 2017

Yeah, EV trip planner is a good site. You could also get the EVTO (EV trip organizer) app if you want to plan on your device. Both take elevation and numerous other variables into account.

Rocky_H | 21 juni 2017

Yeah, that's not hard, since all elevation data is in the existing map data that every navigation system uses. EVTripplanner can show you all of that, and the built-in navigation also includes all of the elevation change on the route into the energy projection. That's kind of the least of your worries since it's such a known factor. Weather, and wind will be your unknowns.

bricha55 | 21 juni 2017

How big of a difference will wind make?

For example if I use what gatorj31 used as an example, how a specific canyon used an extra ~10 miles going up. If there was a strong head wind what would the do?

SUN 2 DRV | 21 juni 2017

I've found wind (and rain) to be a very big factor. With elevation changes you're usually likely to get most of the Down on the same leg as the Up, thus recovering the energy via regen. But with weather it's just a loss of efficiency that you never recover unless you happen to be driving in the opposite direction to capture it as a tailwind on the same leg.

Rain, winds and cold temps are usually bigger factors than hills/mountains as long as you have enough initial energy to get yourself to the top first, then you'll recover much of it on the way back down.

JayInJapan | 21 juni 2017

When I drive up to our local volcano, I'll get 240-300 W/km, depending on traffic conditions. When I get home, I'm at 160-190 W/km, below my total average of 193 W/km.

JayInJapan | 21 juni 2017

W-->Wh

High Plains Drifter | 22 juni 2017

Inclines depending on the angle will have a dramatic effect on your mileage. Unfortunately the downhill slopes does not return all the excess energy consumed by the climb. This is because of the aggressive self-braking performed by the car's motor during descent. Unlike a hybrid car which allows you to coast downhill (zero energy consumption) the Model S requires that you ride the accelerator pedal to speed downhill (small energy consumption).

EVtripplanner will give an approximation for your mileage loss. But for the accurate numbers you will have to gather this information yourself, because trip calculators can account for incline, temperature, payload, and wind conditions. But they do not account for your driving style.

topher | 22 juni 2017

"How big of a difference will wind make?"

Aerodynamic losses are proportional to speed squared. Head winds add directly to speed. So 65 MPH into a 10 MPH headwind is the same as 75 MPH (33% more aerodynamic losses).

Thank you kindly.

Rutrow | 22 juni 2017

Does EVtripplanner receive data back from its users so that it can build more accurate "energy used" maps?

bricha55 | 22 juni 2017

@topher

Thank you for the detailed description, that makes perfect sense now.

@Rutrow

It would seem that EVtripplanner asks for data back, as I was flipping through the different cars they have a beta for the leaf, and there was a plea for anyone using it to let the site know what their actual experience was.

COrich | 22 juni 2017

@High Plains Drifter

Coasting does not enable recovery of any energy at all. It simply means that you use 0 or close to it during the down-hill run. So if you are at 50% at the top of the hill, you will be at 50% at the bottom of the hill.

On the other hand, you can use regen to regulate the speed on the down-hill run. This will at the worst case provide the same as with coasting, but potentially result in 50% at the top and more that 50% at the bottom.

We have driven from Golden, Co up through the canyon to Golden Gate Canyon State Park a few times already this year. The climb is over 3000 ft in less than 20 miles. The return trip nets me about 5% in extra charge from the state park back to Golden. Obvously, I use a lot of energy on the trip to the state park.

BTW, the Tesla trip planner also tracks the SOC charge fairly accurately. Both up-hill and down-hill.

jordanrichard | 22 juni 2017

COrich, HP wasn't saying that coasting gets you anything back. Actually in a Tesla, the only way to "coast" meaning free wheeling, would be to put in in Neutral. HP was saying that one actually has to keep your foot on the accelerator going down hill, though one is still charging while doing so. In our cars, theoretically if one reached the peak of a long hill just as the SOC went from 51% to 50%, going back down could bring you back up to 51%.

SUN 2 DRV | 22 juni 2017

Whether coasting is more efficient than using regen depends on the slope of the hill and whether you use your friction brake or not.

Coasting without the use of your friction brake is very likely to more efficient than using using regen unless you're on a hill steep enough that you pick up significant speed and thus have increased your aerodynamic losses.

If you're on flat ground or a lower grade hill where coasting doesn't increase your speed much using regen would be less efficient than just coasting without using the friction brake.

MarylandS85 | 22 juni 2017

In addition to comments made about coasting vs. regeneration, consider also that regeneration is not 100% efficient. There are losses when converting kinetic energy back to chemical energy. In general, the most efficient way to drive down a hill is to coast (if this keeps you at a safe speed). If one must slow down, regeneration is obviously better than traditional braking.

On Model S vehicles without Autopilot, one can achieve coasting visually by keeping the energy consumption bar right at the threshold between green (regeneration) and orange (consumption). On newer vehicles, I believe the Autopilot display replaces the energy consumption meter I've grown to love on my classic S.

accentcreate | 22 juni 2017

High Plains Drifter " the Model S requires that you ride the accelerator pedal to speed downhill " Sounds like a good reason to have a stick shift for us mountaineers.

JayInJapan | 22 juni 2017

@Majcina describes exactly how I end up with a better than average Wh/km in my car after an A-B-A trip where A is home, and B is in the mountains. Keep the colors to a minimum (unless the road ahead is clear. ;-) ) The only thing to add is that an energy widget can be added on the left or right on the dash.

jefjes | 23 juni 2017

Since this thread is about hills and range, is the RWD only capable of the same one pedal driving as the AWD when it comes to hills? Seems like the additional motor would make the regenerative effect much greater on down hill slopes than the single motor RWD. Another thought is the state of battery charge affecting braking on extended down hill runs. I know when my last Prius battery was full or close to full the car would use engine compression to try to maintain a slower set speed since there was no place to put the regenerative energy in the battery. Does Teslas also get this affect and require the use of more mechanical braking when the battery is near or at full? If so, it may may planning trips in mountainous areas a charging location consideration. For instance, if there are Superchargers near the top of a hill I just expended considerable energy to climb and I know I will have several miles of down hill travel, I may not want to charge as much as I normally would to allow space in the battery to minimize the need for mechanical braking to maintain my desired speed.

Rocky_H | 23 juni 2017

@jefjes, Huh--interesting questions. Regen is pretty strong in both rear wheel and all wheel, so the one pedal driving applies most of the time anyway. I do think the AWD has a little more total regen capacity maybe, but I'm not sure.

Heh, I've run into that very thing with the battery in a hybrid being full and regen not being available. That's hardly ever going to be an issue in a fully electric car, because the battery is just so big. In a hybrid, a couple miles of downhill regen can fill it from half to full, and then you have no more regen. If you've done any decent bit of driving from an electric car to where you see a little bit of space at the top of the battery, you have many many tens of miles of regen to fill that up.

The part where you may see this sometimes though is if you do charge the car all the way up to full. It really doesn't have any place to put regen energy, so it's not available at first, but that starts to open up within the first couple of minutes as you drive and make some room in the battery.

jefjes | 23 juni 2017

@Rocky_H
Thanks for the input. I test drove a MS 90D and the one pedal experience was so amazing that when I finished, I was sure my M3 would have to be a AWD. From several posts, it sounds like RWD may work just fine but I will still need to see the cost and time of delivery delay before making a final decision.

Haggy | 23 juni 2017

EVTripplanner works. So does the car's navigator and trip planner. I've taken my car from sea level to over 7000 feet and had the trip planner tell me that it would use well over half my battery range. But the trip back down used a fraction of it, so even though I started the remaining trip with a rated range well under what I needed to get to a supercharger, the navigator had a better idea based on an actual route and got it right. So seeing the rated range in the display is not what you need to look at when there will be lots of changes in elevation, but the graph based on the selected location will show you what you need to know.

When going downhill under that circumstance, you can watch the Wh/mile being used go way into negative territory and although you might not see the range increasing fast, it might not decrease in 20 miles, meaning you generated enough electricity to go that far, accounting for the likelihood that there are some parts that go up and others that go down and the energy generated on the way down was enough to handle the uphill stretches. .

MarylandS85 | 23 juni 2017

@jefjes
I own a RWD S85 and had an AWD S90D for a couple weeks. The regen is definitely noticeably more on the AWD, but it's certainly not paltry on the RWD. I promise that one pedal driving is the norm for both cars.

As far as your question about how a full battery affects regen, Rocky explained it well in his last sentence. I'd also say that regardless, you should rarely Supercharge to 100% because those last few electrons take a long time to acquire.

jefjes | 23 juni 2017

@Majcina
That is the exact kind of feedback I find of value while trying to decide on whether to wait on the AWD or not. Having current Tesla owners that have experience with both is great. Thanks for your insight.

Rutrow | 24 juni 2017

Sounds like they need to install Super Chargers at the top of the uphill side of mountains, but not at the top of the downhill side.

MarylandS85 | 24 juni 2017

@jefjes
You're very welcome! I'm a new Model S driver myself (3 glorious months!) and also have a Model 3 on preorder. I've never been a car enthusiast, but I'm passionate about tech and environmentalism, and Tesla fits both niches nicely. Hope you fall in love with your future Tesla too.

@Rutrow
Lol. In my day, it was uphill both ways....

topher | 24 juni 2017

So we have an idea of the amount of energy involved here:

A 2 ton car going up or down about 700 feet of elevation change their potential energy by 1 kWh.

Thank you kindly.

eandmjep | 24 juni 2017

I liked the above "What goes up must come down". Unless of course you don't for a while ;) but I do see on the down hill side even if you don't gain energy you would still be covering a distance using less energy. A 10% overall loss of range would be acceptable. 60 miles traveled, 30 up 30 down 66 miles of range used so 40 up and 26 down.

Ross1 | 25 juni 2017

Coasting is illegal in most places. Check your own State laws.
It is also dangerous. Google it.

MarylandS85 | 25 juni 2017

@Ross1
Coasting a car with an internal combustion engine is driving in neutral. It is dangerous because you can't accelerate without putting it back into gear first. Coasting a Tesla is nothing like this. You have your foot on the accelerator half way. To speed up, you push a little harder. To slow down, you release a little more.

topher | 25 juni 2017

Many ICE cars (e.g. Prius) will coast while "in gear" and it no more dangerous than anything else you do in a car, and a lot less dangerous than things many people brag about.

Thank you kindly.