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400 miles on one charge... done!

Dave Metcalf and his son drove for roughly 16 hours today in Florida, trying to travel 400 miles on a single charge in their Model S. I believe they drove at a steady 25 mph to get maximum range.

A few minutes ago, they crossed the 400-mile mark, successfully setting a new record. From the photos Dave posted, it seems his Model S still had 18 miles left in it at that time. :-)

@Terry&Kevin

The car does go 300 miles @ 55mph under ideal conditions. I don't understand your complaint.

Why would they bother telling people how far it can go @ 27 mph when no one drives that speed? I mean, not many drive 55 either, but it seems like a reasonable number to use as a benchmark. it should be obvious that your range will vary according to environmental conditions and your driving habits, just as with any other car.

To be fair to T&K, it seems that the "variance" is a bit more than they counted on. If you're "on the bubble", that can be a problem. Perhaps skill and self-restraint will gradually resolve the issue.

So what did he win?

I'm curious how owners that travel long distances between charges feel the current projected range algorithm in the Tesla successfully predicts their true range at the very beginning of a trip?

Like most new owners, I've been driving around showing the car to friends and relatives, and you know that means I'm a little heavy on the pedal. The projected range is definitely less than routine, but I expect that as the driving becomes more regular, the discrepancy will shrink.

I've had a Leaf for a year, and the projected range that Nissan calculates is way too optimistic, despite a very consistent driving pattern and route to work. It also varies considerably during the drive when going up and down over relatively small hills, making it almost impossible to predict your true range at the beginning of a trip. How is Tesla doing?

It will be very helpful if somebody could try to calculate the same on a 32 - 35 mph speed. That sounds like an average city/hwy usage. (ylyubarsky)

Tesla put up a small (beautiful) web app which you can use to calculate your (estimated) range under various conditions (including heating/AC and windows up or down):
http://www.teslamotors.com/goelectric#range

The speed dial in that web app it limited to 45-65 mph for highway driving. In city driving mode, there is no speed dial available but they probably make similar assumptions as to what the average speed is, like you do. On the other hand, city driving requires much more deceleration/acceleration which also eats into the range (given the S's substantial weight).

Scroll down a little more on the same page, beyond the range app, and you find a supplementary chart that shows how range relates to speeds that are not available on the app's speed dial.

I don't see anything about elevation changes on the range app. If you start and end any given segment of a road trip at the same elevation, all else being equal, then any intermediate elevation changes cancel out (basic physics – gravity is a "conservative" field) - the only exception being that if you have a really high point in the middle of the leg, you'd better make sure you don't run out of battery at the high point! - but if that's not the issue, you'll get back all the extra energy you lost going uphill when you come back downhill, and it cancels out.

BUT if you know, in advance, that a particular destination where you're going to need a recharge, is at a different elevation than where you are now, you have to take than into account. You can't blame this basic fact of physics on Tesla, though I don't think they emphasize it adequately. To quantify this for you, when I drive my Roadster uphill from Mesa, AZ, to my summer cabin in Forest Lakes, AZ, the 3000 lb Roadster (2700 lb curb weight + 300 lb passengers & luggage) consumes roughly an extra 1 kWh for each 1000 ft increase in elevation. I have to climb 6000 ft, so I lose roughly 6 kWh of charge simply due to the climb. If I'm averaging 4 mi/kWh, that means I give up 24 miles of range going uphill. So if I have to go 120 miles, that means I have to add 24 miles of range to my initial charge, and if the meter doesn't say at least 144 miles, I can be sure I won't make it! On the other hand, coming home, I can start with only 96 miles of range showing, and make the 120mi trip just fine. (Of course, I don't really cut it this fine, but the point is, you have to take the elevation into account on long road trips where you have limited charging options.) As a side note, this means I can do the 240 mile round trip on exactly 1 full charge, but when I get to the cabin, it looks like I've used 65% of the battery, and the trip home looks impossible – but it's actually not.

The Model S will be "worse," in this sense, because the GVW is considerably higher (for example, at 4647 lb curb weight + 300 lb of passengers/luggage, you're talking a full 66% higher!). In other words, for the Model S, if you had a 3000 ft climb from LA to Tejon Pass, you'd need to factor in an extra 3x1.66 kWh or an extra 5 kWh of energy required for the uphill climb. How many miles does that extra 5 kWh represent? If the Model S is rated at 300 miles (85 kWh battery) at 55 mph, that comes out to 3.4 mi/kWh; but at 70 mph, that V-squared aerodynamic loss takes you down to just 2.2 mi/kWh, and at 75 mph, down to 1.9 mi/kWh! So, somewhat counter intuitively, the faster you would have been driving, the less range loss that extra 5 kWh represents: 9 miles at 75 mph, 11 miles at 70 mph, or 16.5 miles at 55 mph. But remember, if you're going to drive 75 mph, your 100% battery charge of an 85 kWh battery is only going to take you 161 miles – not 300! Consider now the possible trip N from LA. Depending on exactly where you start, it might be 100 miles to the top of Tejon Pass. That's 53 kWh of charge required, plus that extra 5 kWh for the climb. So you've got to have 58 kWh of charge simply to get to the top of the pass (or 68% of a full-range charge). Yet, interestingly, if you did get all the way to the top of the pass, it's only another 19 miles downhill to the Tejon Ranch Supercharger, and because you'll actually gain back 4000 ft of elevation (looks like Tejon Ranch is about 1000 ft lower than LA), you'll actually gain back 6.6 kWh on the downhill side. That's actually 13 miles of range at 75 mph, so if you had even just 6 miles of nominal range left at the top of the pass, you'd make it all the way to the Supercharger 19 miles away. (And if you slowed down to 55 mph, you could actually "loaf" the entire distance and gain 23 miles of range from the elevation drop, and your net range would actually be 4 miles larger by the time you got to the Supercharger than it was at the top of the pass!

But the point is, as others have mentioned, one of the mind-set issues with EV's is that because they're so much more efficient than ICE's, you really do notice that speed vs. range tradeoff (over a very wide range of speed). Everybody knows your mileage goes down as you drive faster, but in an EV, where charging options are limited (and time-expensive), you really have to be aware of it – at least, until we get "nominal" ranges of 1000 miles. (And of course, even then there will still be bozos who run out of energy for lack of planning.) For me, 300 miles of range (or 240 for my Roadster) is plenty, until I start planning road trips. Then I really have to plan. I think of it more as a "pilot" mentality than a "driver" mentality. But as we get more accustomed to EV's, we'll all start to think more carefully.

Very good, except of course you don't recover 100% of the climbing energy through regen, as the S is only able to get 60kW max, and there are some inefficiency costs. Going uphill and then back down isn't a zero-energy wash, IOW.

...unless you don't go to regen. Remember that at 60mph car uses 20kW just to maintain speed, so you can decelerate at 20kW worth before you even go to regen. That's not insignificant deceleration. 80kW power to get full regen is quite steep hill.

This is the one case in RL physics where it should be zero energy wash, unless car has more inefficiencies when load is small/high compared to flat plane driving.

Thanks all. It was a bit tedious to drive so slow for so long, but one of my other hobbies is running ultramarathons so it was not too bad and was through very pretty wildlife preserves and mostly slow, flat rural roads. Most drivers were cheering us on with the goal painted on the rear window. Even though I live in FL, I don't usually drive that slow. Real world, my 104 mi commute is flat and fast with prevailing traffic at 75-80+ for 80 pct of the trip from the coast to Orlando and back. Even if I "misbehave" a little, I am still spending 5x less than gas based on low FL electric rates (8.4-10.4 cents) vs my other 25mpg car.

JB Straubel called yesterday and asked if we could write a Tesla blog post together this week, so I'm working on that for later in the week with some more details. More to come and thanks for the support. Adam and I had fun.

@dmetcalf

UCF alum here. Congrats on the record drive. Could you include a Google Map of the route in the blog post?

I think people not from Florida will appreciate how far that trip was once they see it mapped.

Here are some specific numbers to consider, on how much gravitational potential energy is released going downhill at the indicated speeds and grades:

5000 lb GVW, 10.79% grade, 75 mph: 80 kW of regen
5000 lb GVW, 8.07% grade, 75 mph: 60 kW of regen
5000 lb GVW, 8.07% grade, 60 mph: 48 kW of regen

Those are pretty darned steep grades, and if as Timo says it takes 20 kW simply to maintain speed at 60 mph, even that last example says you'd only be putting 28 kW back into the battery, as 20 kW of that 48 is maintaining your speed. Here's another interesting physics problem for you: given a certain regen rate, what's your terminal velocity as a function of grade? I.e., without your foot on the brake OR the accelerator, how fast do you go downhill on a given grade? Or to put it even another way, given a certain regen rate, what's the steepest grade you can coast down without exceeding a given speed limit?

I posted a pdf of the entire route as a Googlemap toward the end of the TMC Forum topic the MODS started:

http://www.teslamotorsclub.com/showthread.php/11699-Dave-Metcalf-and-son-Adam-break-the-400-miles-challenge!-Incredible/page15

20kW at 60mph is close to RL power usage based on posted energy usages:

20000W/60miles/h = 333Wh/mile.


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