Love my Tesla, but almost got stranded because of way out of whack mileage estimate

[David_Cary]

Two comments. There was a wind speed correction somewhere in this thread with 30 mph headwind and I think only 5% was deducted. That is absolutely crazy - it should be far more than that and depends a lot on ambient speed. If you are going 50 mph, the wind would create drag like it was 80 mph which would be close to a 50% decrease in range. Wind is well over 90% of spent energy at freeway speeds usually unless you have really draggy tires.

I had an instant mpg rating with my Civic Hybrid and had some head winds on a long trip - I had a mpg in the high 30s instead of the usual 50. I have no idea what the head winds were but they were significant. So that was a 30% hit.

Also - coasting down hills in N is almost always better than regen. People need to remember that regen is not perfectly efficient. So it is usually better to use that energy to speed up a bit. Now you do create extra drag by the higher speed and in the extreme that would be worse than the regen loses. But that is the exception. The best way to counter this is of course slowing down at the apex of the hill so that you don't get too fast on the down hill.

Ideally, the car should have a wind speed indicator.

 

[russman]

Car is being picked up on Friday. The good news is I'm on the West Coast and thus don't have the difficult weather issues, but it's disheartening to have people dismiss people who have these issues as: You didn't plan, or you didn't calculate well, or you shouldn't have been driving that fast.

The fact that we have to consider driving 50 mph is a little disheartening to me. I want to take a trip to Napa in the new Tesla, but I'm concerned about how fast to drive, will I have enough to get back, will I have to find a place to charge when I'm there. Until charging stations are prevalent, this will affect the impacts of EV. Yes, some of you are extremely intelligent and able to calculate on the fly actual mileage available based on current usage, but the normal user will not be able to do it. People get stranded in gas cars now already, it's only going to get worse with electric cars.

I've never thought about a road trip to Napa from the Bay Area so much before. I've emailed wineries if they have charging stations, I've looked up chargepoint, I've looked up evtripplanner, just to go to Napa (only about 65 miles away), which I would normally just jump in a car and go. Maybe I'm just being overly cautions, but it doesn't sit in the back of my mind.

 

[FlasherZ]

I've never thought about a road trip to Napa from the Bay Area so much before. I've emailed wineries if they have charging stations, I've looked up chargepoint, I've looked up evtripplanner, just to go to Napa (only about 65 miles away), which I would normally just jump in a car and go. Maybe I'm just being overly cautions, but it doesn't sit in the back of my mind.

65 miles away, you'll be just fine without having to worry at all. Don't worry, especially in the bay area. You'll be able to drive normal speeds and not have to be concerned.

We have to worry because we have 30 mph winds in the middle of winter with < 32 degrees, pack heating and everything else. That's when you have to be careful not to overshoot things.

 

[jerry33]

I've looked up evtripplanner, just to go to Napa (only about 65 miles away), which I would normally just jump in a car and go.

That's is all I'd do in the Tesla too. It's the exceptions in very bad weather that reduce the range significantly, and even then you're going to have close to 180 miles, unless you really are slugging through three inches of snow into a strong headwind. A few weeks ago I went to a car show 110 miles away, stayed all day with people going in and out of the car, drove back and still had 60 miles left. I've had more close calls in the previous ICE cars than I have in the Tesla.

 

[Ugliest1]

Car is being picked up on Friday.

Congratulations! You're so in for a treat, as you probably already know.

I want to take a trip to Napa in the new Tesla, but I'm concerned about how fast to drive, will I have enough to get back, will I have to find a place to charge when I'm there........<snip>........... Maybe I'm just being overly cautions, but it doesn't sit in the back of my mind.

I'm not one of the math whizzes either. And I think the overcautiousness that you describe is completely normal for us new owner trip planners -- I have been planning and replanning for hours, over days, for an upcoming 6 week mostly-supercharger-but-some-off-beaten-track trip. But I'm also confident that my planning, which includes healthy buffers and a few Plan B's and Plan C's, will mean we won't get stranded. Then I'll just watch the nav "miles left" estimate against the "projected range" estimate (with an eye on "rated range") to see whether Plan A is on track or I have to start looking at the other options. I'm also pretty confident that, while I'll still plan, once I have multiple experiences, I won't have to plan as much.

 

[GlennAlanBerry]

Going 65 miles each way won't be a problem at all, especially in the Bay area. In other parts of the country, a long road trip still takes a little more planning and some situational awareness to adjust your behavior based on the conditions and your energy usage as you are driving. This situation is rapidly improving as the SC network is built out, and an increasing number of other charging stations are being built.

 

[ChadS]

My simple trip planning rule (see my signature for more details):

Every time you charge, make sure you have 50% more miles of range than the distance to your next charging point.

That's it. Super simple. I never have to worry about slowing down, turning off the heat, and I never wonder if I am going to make it. (Sure, it is slightly annoying when it's 220 miles to the next Supercharger - I can't charge to 330 (thanks, BB) so I have to plan - though not necessarily use - a stop at a 30A J1772 station within 175 miles. But the peace of mind while driving is well worth it, and I usually don't have to make that intermediate stop. As more Superchargers get built, having to do even this small planning step will become less frequent).

 

[Kraken]

Car is being picked up on Friday. The good news is I'm on the West Coast and thus don't have the difficult weather issues, but it's disheartening to have people dismiss people who have these issues as: You didn't plan, or you didn't calculate well, or you shouldn't have been driving that fast.

The fact that we have to consider driving 50 mph is a little disheartening to me. I want to take a trip to Napa in the new Tesla, but I'm concerned about how fast to drive, will I have enough to get back, will I have to find a place to charge when I'm there. Until charging stations are prevalent, this will affect the impacts of EV. Yes, some of you are extremely intelligent and able to calculate on the fly actual mileage available based on current usage, but the normal user will not be able to do it. People get stranded in gas cars now already, it's only going to get worse with electric cars.

I've never thought about a road trip to Napa from the Bay Area so much before. I've emailed wineries if they have charging stations, I've looked up chargepoint, I've looked up evtripplanner, just to go to Napa (only about 65 miles away), which I would normally just jump in a car and go. Maybe I'm just being overly cautions, but it doesn't sit in the back of my mind.

ive done vacaville to sj multiple times just fine without charging. Granted, I have lots of outs to charge if I need it, but there are chargers up here too.

not sure how they are going to calculate a real wind speed without something like a pitot tube. Just taking forecast winds would be a bad move. The only thing I can think of is calculating based on avg energy use, but there is already a mechanism for that and too many other factors are involved in that.

 

[Benjamin Brooks]

My simple trip planning rule (see my signature for more details):

Every time you charge, make sure you have 50% more miles of range than the distance to your next charging point.

That's it. Super simple. I never have to worry about slowing down, turning off the heat, and I never wonder if I am going to make it. (Sure, it is slightly annoying when it's 220 miles to the next Supercharger - I can't charge to 310 so I have to plan - though not necessarily use - a stop at a 30A J1772 station within 175 miles. But the peace of mind while driving is well worth it, and I usually don't have to make that intermediate stop. As more Superchargers get built, having to do even this small planning step will become less frequent).

You can't charge to 330 miles either

 

[Benjamin Brooks]

I've never thought about a road trip to Napa from the Bay Area so much before. I've emailed wineries if they have charging stations, I've looked up chargepoint, I've looked up evtripplanner, just to go to Napa (only about 65 miles away), which I would normally just jump in a car and go. Maybe I'm just being overly cautions, but it doesn't sit in the back of my mind.

Just go to ZD Winery in Napa. They have a Model S HPWC for customers (you'll get 50+ MPH of charge back).
Their wines are great too (OK, I am a little biased because my relatives own the winery... but it's the only place I know of in Napa with a public & free HPWC)

 

[VolkerP]

not sure how they are going to calculate a real wind speed without something like a pitot tube. Just taking forecast winds would be a bad move. The only thing I can think of is calculating based on avg energy use, but there is already a mechanism for that and too many other factors are involved in that.

Since increased energy use is the result of adverse conditions, Tesla could use a similar approach than the traffic congestion display in the google nav screen: crowd source.

The fleet of Model S should report energy consumption figures, speed, outside temp, other car parameters. Tesla can verify its range calculation model on the fly and fine tune the predictions to local ambient factors. Voila. You will see red areas/routes of +400Wh/mi. Plan accordingly if you drive into them.

 

[Tasdevil]

Just curious, do we think this situation is worse than with an ICE vehicle? Or do we just not notice in that case because fuel is ubiquitous?

I have driven an underpowered, unaerodynamic work van with ladders on roof racks and heavy tools in the cargo bay. While having very strong sideway winds almost blowing me off the road. I had to drive with the steering wheel on an angle and the pedal to the floor. So I used a lot more energy because of wind and load etc.

However when its cold outside a petrol car has more power and the heater just uses the heat loss from the engine.

And most ICE cars have a greater range as well.

 

[woof]

a wind speed indicator.

Yes! And the guess-o-meter should take it into account (probably making it even more wildly erratic...).

 

[Plug Me In]

I've done the 29 North drive from Burlington a few times and there's some elevation gain on the whole route, but especially Lynchburg to before Lovingston. I've found the northbound trip is a little less efficient than the southbound. When the weather is nasty I usually feel most comfortable with a > 33% mileage buffer so I probably would have set off on that trip with the same confidence. You should have turned off the heat and let your passion for the Wahoos keep the car warm.

Glad it worked out OK and good luck to the Hoos in the tourney, they're #2 in my heart after the Blue Devils!

 

[SFOTurtle]

Also - coasting down hills in N is almost always better than regen. People need to remember that regen is not perfectly efficient. So it is usually better to use that energy to speed up a bit. Now you do create extra drag by the higher speed and in the extreme that would be worse than the regen loses. But that is the exception. The best way to counter this is of course slowing down at the apex of the hill so that you don't get too fast on the down hill.

I guess it depends on the height and length of the hill. Perhaps for very short, low hills, not using regen might be more efficient. Maybe. But if you're coming down a steep and long mountain pass -- real elevation change -- I can't conceive how coasting, and riding manual brakes for elevation changes of several thousand feet, could even remotely approach efficiency of regen. You're just giving away all of that energy you could be pushing back to the battery and there's no way that coasting out at the bottom of a mountain pass will net anything more than a fraction of what you'd gain back.

 

[physicsfita]

I guess it depends on the height and length of the hill. Perhaps for very short, low hills, not using regen might be more efficient. Maybe. But if you're coming down a steep and long mountain pass -- real elevation change -- I can't conceive how coasting, and riding manual brakes for elevation changes of several thousand feet, could even remotely approach efficiency of regen. You're just giving away all of that energy you could be pushing back to the battery and there's no way that coasting out at the bottom of a mountain pass will net anything more than a fraction of what you'd gain back.

From my experience driving a Prius, you are correct for the situation you envision -- if you have to ride a friction brake to slow down, you should regenerate instead if that will provide all your braking. Friction brakes will convert all you kinetic energy into heat; regen will divert some of that to the battery. I think the previous posters were envisioning a case where you could coast all the way down safely/legally. If that's the case, you are better off in most cases to coast, since there are losses in regen. (In another thread, it was demonstrated that there are exceptions to this guideline in some oddball cases.)

 

[David_Cary]

No way no how was I suggesting braking. The OP was not driving in Mountains. Hills was the term used I believe.

Coasting and speeding up is generally better than regen on hills. If you speed up more than say 20% (depends on baseline speed), then regen is better. Braking is never the right answer.

 

[huntjo]

No way no how was I suggesting braking. The OP was not driving in Mountains. Hills was the term used I believe.

Coasting and speeding up is generally better than regen on hills. If you speed up more than say 20% (depends on baseline speed), then regen is better. Braking is never the right answer.

Yeah but it should be noted that you have to coast "correctly" for it to be more efficient. I'm not an expert hyper miler so I don't even fool with it, but I seem to recall that one must coast downhill allowing to gain speed, followed by coasting uphill allowing oneself to slow down considerably. As I personally find it annoying driving behind someone whose speed varies that much, I don't like the idea of becoming "that guy" either. Maybe once everyone has adaptive cruise control our cars can do this for us to conserve energy use. But until then, it's too much work.

 

[cinergi]

This is why I wish they'd bring back the ability to set the instrument cluster range display to projected instead of rated (or ideal).

 

[Todd Burch]

not sure how they are going to calculate a real wind speed without something like a pitot tube. Just taking forecast winds would be a bad move. The only thing I can think of is calculating based on avg energy use, but there is already a mechanism for that and too many other factors are involved in that.

They don't need to use forecast winds, or use a pitot tube. Most airports have hourly observations (METARS) that give actual wind speeds. Other facilities gather actual hourly wind speed data as well. This data should be plenty accurate for nav calculations.