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Highway Range Ignorance
- Thread starter WhiteKnight
- Start date
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- Model S
Set aside a little money for a car rental fund and then you don't have to worry. Like Alan said, you'll be loving the Model S 99% of the time!!
Alan, you raise a great point. 0-60 mph isn't particularly useful in every-day driving (although there're a few places at toll plazas where 10-70 mph is safe and fun). 0-40 mph is what I use most around the city; 50-80 mph is what I care about for highway.
If we assume that the powertrain is identical among the (non-sport) versions, the lower 0-60 performance is a result of limited current draw. Therefore, it's likely that 0-30 performance will be nearly identical across all three (or even slightly better with a smaller, lighter battery); the difference will lie entirely in the 30-60 half of the split. Which would further suggest a very stark difference in the 50-80 overtaking time among the three battery packs.
I've figured the CdA by taking the dimensions and images from web site and calculated how much area the silhouette took.
W x H x percent area of silhouette x Cd = CdA
77.3" x 56.5" x .81 x .225 = 5.53 Model S
72.9" x 44.35" x .8 x .35 = 6.29 Roadster
Then I calculated the formulas from the roadster efficiency and range spread sheet and used the CdA ratios above
Wh/mile =
(179.9*v^-1.002) Ancillary Wh/mi
+ (-0.0003* v^2+0.0936*v +51.871) Tires Wh/mi
+ (0.02899* v^2 ) Aero Wh/mi [roadster has .0309 *v^2]
+ (0.006 * v^2 + 0.1669*v+51.667) Drivetrain Wh/mi
+ (24 Wh/mi) RoadsterToSAdjustment Wh/mi (57Wh/mi for 85kWh pack = 300miles @ 55mph)
dividing by pack size yields a mileage graph like:
At 75 Mph range is
40kWh= 114 miles
60kWh= 171 miles
85kWh= 243 or 225 miles -- the 85kWh pack was calculated 2 ways.
Where the @55mph = 300 miles and where the Ancillary+Tires+Drive Train curves had the same adjustment factor as the 40 & 60 kWh packs.
W x H x percent area of silhouette x Cd = CdA
77.3" x 56.5" x .81 x .225 = 5.53 Model S
72.9" x 44.35" x .8 x .35 = 6.29 Roadster
Then I calculated the formulas from the roadster efficiency and range spread sheet and used the CdA ratios above
Wh/mile =
(179.9*v^-1.002) Ancillary Wh/mi
+ (-0.0003* v^2+0.0936*v +51.871) Tires Wh/mi
+ (0.02899* v^2 ) Aero Wh/mi [roadster has .0309 *v^2]
+ (0.006 * v^2 + 0.1669*v+51.667) Drivetrain Wh/mi
+ (24 Wh/mi) RoadsterToSAdjustment Wh/mi (57Wh/mi for 85kWh pack = 300miles @ 55mph)
dividing by pack size yields a mileage graph like:
At 75 Mph range is
40kWh= 114 miles
60kWh= 171 miles
85kWh= 243 or 225 miles -- the 85kWh pack was calculated 2 ways.
Where the @55mph = 300 miles and where the Ancillary+Tires+Drive Train curves had the same adjustment factor as the 40 & 60 kWh packs.
ChadS
Last tank of gas: March 2009
I completely get that it will not be your road-trip car.
But if Tesla builds out the Superchargers or allows access to CHAdeMO stations, it absolutely will be my road trip car. This is not because I do not understand how the car will perform on the road. It's because my current road trip car is a Roadster, and the Model S has more room and a little more range, both of which are very small peeves with the Roadster. The Roadster's charging speed is my only big peeve, and with Superchargers or at least CHAdeMO, it will be far better.
If you'd rather rent a gas car for long trips, I'm totally OK with that. But I'd rather spend some time along the way doing something outside of the car (which my wife would insist on even if we were in a gas car; and even by myself I often want to sleep, eat, visit friends, get exercise, etc). If I was in enough of a hurry so that didn't work, I'd fly.
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ljbad4life
Member
Totally Agree. 250 mile range is perfect for my situation and many others. If it doesn't work for you move on.
Having just discovered this thread through a pointer...
...looking at this, I think the model S is *exactly the right* road trip car for me.
First of all, New York State has a top speed limit of 65 on expressways. Forget 75.
Second, I already take rural roads -- speed limit 55 -- *by preference* over expressways. A drive down the uncrowded 5-and-20 to Cooperstown is a relaxing event, where one can comfortably pull off at any number of interesting tourist spots/shop/restaurants/etc. as one notices them, bringing back thoughts of classic road trips from the 20s to the 50s. A drive down the NYS Thruway (the parallel expressway) is a miserable slog interrupted only by taking an exit to an asphalt wasteland to get chain fast food....
Those of you who take fast expressways -- or even more extreme, autobahns -- for point-to-point trips will have to contend with the reduced range. For me, I think I'm going to get that full 320 mile range (with aero wheels).
You clearly all live somewhere where the speed limits are higher.
...looking at this, I think the model S is *exactly the right* road trip car for me.
First of all, New York State has a top speed limit of 65 on expressways. Forget 75.
Second, I already take rural roads -- speed limit 55 -- *by preference* over expressways. A drive down the uncrowded 5-and-20 to Cooperstown is a relaxing event, where one can comfortably pull off at any number of interesting tourist spots/shop/restaurants/etc. as one notices them, bringing back thoughts of classic road trips from the 20s to the 50s. A drive down the NYS Thruway (the parallel expressway) is a miserable slog interrupted only by taking an exit to an asphalt wasteland to get chain fast food....
Those of you who take fast expressways -- or even more extreme, autobahns -- for point-to-point trips will have to contend with the reduced range. For me, I think I'm going to get that full 320 mile range (with aero wheels).
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stopcrazypp
Well-Known Member
Virginia (where Todd lives) raised their max speed limit to 70 (it was previously 65).
http://www.virginiadot.org/info/faq-speedlimits.asp
I live in California, where most roads have an absolute top speed limit of 65 (with 70mph only where posted, which is rare), yet most people drive 70-75mph anyways (especially in the far left fast lane; don't even try driving at 65mph in that lane, you will definitely get honked at). And CA isn't even one of those states that have explicit tolerance to adjust for speedometer error (a cop can pull you over for doing 66mph in a 65mph zone, although in real practice cops don't bother unless you are noticeably faster than the flow of traffic or at least 10mph over the posted limit). I guess in NY, people actually obey the speed limit (maybe the police actually enforce it strictly).
I know people who also take rural roads by preference. Its usually to avoid possible traffic jams from commuters/accidents on major highways. The rural roads take longer vs an ideal situation on typical highways, but you are pretty much 99% guaranteed to make the trip in the estimated time on a rural road, while on a highway the chance of a jam can be quite high (I've been caught in a few before).
This will be the hardest adjustment for me. I drive I-95 most often and I-81 through PA, usually between 75 and 80 mph depending on traffic conditions and speed limit. I've found that as long as I'm within 15 mph of the speed limit I'm not bothered.
Having grown up in SE Michigan, that speed is ingrained in me. Go to Detroit and drive to Ann Arbor or Jackson. If you're below 75 mph (the speed limit is 70 most of the way) you're getting your doors blown off.
Having grown up in SE Michigan, that speed is ingrained in me. Go to Detroit and drive to Ann Arbor or Jackson. If you're below 75 mph (the speed limit is 70 most of the way) you're getting your doors blown off.
bonnie
I play a nice person on twitter.
I've took my Roadster on a 1-week road trip last summer that put approx 1300m on the car (and that was more 'drive to destination, hang out the majority of the week, drive home'). I'm not going to say it was without challenge (always had a backup charging plan), BUT it was simple enough that I decided to go 100% electric by adding either the Model S or Model X and getting rid of my Prius.
Before I bought my Roadster, I was worrying about range, 'what will I do if' scenarios flooding my head. But a good friend who has one of the early Roadsters kind of barked at me (thanks, Steve): "When you fly a plane, you plan where you're going to refuel. Don't make a big deal out of this, don't over think it."
My roadtrip was uneventful, I took plenty of side trips, I charged at every opportunity, and it convinced me I didn't need an ICE. Don't over think this. Get the Model S (or whatever BEV you are lusting after), drive it, and then decide if you need an ICE or not. We all have different needs.
Before I bought my Roadster, I was worrying about range, 'what will I do if' scenarios flooding my head. But a good friend who has one of the early Roadsters kind of barked at me (thanks, Steve): "When you fly a plane, you plan where you're going to refuel. Don't make a big deal out of this, don't over think it."
My roadtrip was uneventful, I took plenty of side trips, I charged at every opportunity, and it convinced me I didn't need an ICE. Don't over think this. Get the Model S (or whatever BEV you are lusting after), drive it, and then decide if you need an ICE or not. We all have different needs.
Indeed, but I can refuel a plane in 20 minutes from touchdown to takeoff if I select the right airport. Until quick chargers are in place it's a little more complicated. I haven't lived it the way you have with the Roadster but hanging out at a campground for 2-3 hours to pick up another few hours driving is a bit of a drag.
We have to also remember that the average joe is going to find that plotting out a course for every trip is a big negative of EVs. Not everyone has the patience or dedication. There's also the instances like the leaf driver that ran into out of service chargers.
Once the network is beefier and/or charge times come down, it should get easier though. I can only imagine what it was like before gas stations became ubiquitous.
Todd Burch
14-Year Member
It's also important to note that the EV road trip experiences from those on the US West Coast are going to be less challenging in general than others. Nowhere else in the country is the EV infrastructure (for charging faster than NEMA 14-50) better supported.
