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Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

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Re: Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

#91

Post by NickM »

rdl wrote: post #65
NickM wrote: post #58

Earlier quoted context omitted.

Sporty behavior not on a highway is still going to get better consumption than extremely high speed driving, because wind resistance rises as the square of the velocity. If you double your velocity, then air drag increases by 4x, so if users are quoting 8L/100 on 120-130km/h then you can expect to get about 32L/100 going 250km/h. With a 70L tank at 250km/h you may well exhaust the tank in under an hour. These are wor…

Actually it doesn't look that bad. http://www.automobile-catalog.com/economy/2014/1900655/bmw_5... Fuel consumption: in liter / 100 km Estimated fuel consumption by constant speeds on top gear, steady ride without acceleration or braking, flat concrete or tarmac surface, no wind by 50 km/h (31 mph): 8 l/100 km by 60 km/h (37 mph): 6.8 l/100 km by 70 km/h (44 mph): 6.5 l/100 km by 80 km/h (50 mph): 4.9 l/100 km by 90…

Your link says that those are "estimated fuel consumptions", but I'm somewhat inclined to doubt the veracity of these estimates: between 120 km/h and 240 km/h wind drag is going to quadruple, and ICEs get lower efficiency at higher RPM. So if the efficiency falls by less than 50% when you double the speed, then that implies that tire drag and internal friction represent the majority of the force you're overcoming at highway speeds, which is definitely incorrect. Something doesn't add up.

Re: Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

#92

Post by Zikes »

Avshalom wrote: post #85
revelation wrote: post #79

Earlier quoted context omitted.

So? They went straight for the west coast and skipped all the barren nonsense in the middle. In most every vast country, population density is a function of distance to water.

Kansas had a million people in it by the time the car was invented, the middle was not skipped.

Yep, good ol' Mississippi River goes straight up the middle.

Re: Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

#93

Post by haldujai »

thrownaway2424 wrote: post #67
Zikes wrote: post #54

Earlier quoted context omitted.

Distances aren't big because gas is/was cheap, they're big because nobody wants to pay $2,000/month for a crappy one-bedroom apartment within biking distance of their job. Distances ARE big because America is so big, and even now there's still plenty of land to be cheaply bought and decently priced housing built upon. For the past decade everyone's been balking at the rising gas prices, and so far as I know no two pl…

Yeah, nobody wants to live in those apartments, that's why the rents are so high!

Or you know, people eventually grow up / start families and realize for a short commute they could raise a child in a much safer environment with better facilities out in the suburbs. Or even they themselves one day decide they want a garden, and a personal swimming pool, and a house.

Re: Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

#94

Post by rdl »

NickM wrote: post #91
rdl wrote: post #65

Earlier quoted context omitted.

Actually it doesn't look that bad. http://www.automobile-catalog.com/economy/2014/1900655/bmw_5... Fuel consumption: in liter / 100 km Estimated fuel consumption by constant speeds on top gear, steady ride without acceleration or braking, flat concrete or tarmac surface, no wind by 50 km/h (31 mph): 8 l/100 km by 60 km/h (37 mph): 6.8 l/100 km by 70 km/h (44 mph): 6.5 l/100 km by 80 km/h (50 mph): 4.9 l/100 km by 90…

Your link says that those are "estimated fuel consumptions", but I'm somewhat inclined to doubt the veracity of these estimates: between 120 km/h and 240 km/h wind drag is going to quadruple, and ICEs get lower efficiency at higher RPM. So if the efficiency falls by less than 50% when you double the speed, then that implies that tire drag and internal friction represent the majority of the force you're overcoming at…

Cars have geared transmissions. Cars designed for the Autobahn (most high end German cars) have gearing optimized for decent cruise range at 120-180 km/h.

The engine is sized for peak acceleration (and marketing). It has a turbo (in the 535d; the 550d has 3....), which helps somewhat without adding more fuel consumption, but still, a 300hp engine is pretty big.

Basically, to cruise along at 120kph in a reasonable car with reasonable Cd probably is about 20-30hp (yay for mixing metric and imperial units...). Wind is probably 20hp of that. The engine is less efficient at low output (specific output), so you won't get fuel consumption at 10% power which is only 10% of peak fuel consumption.

Wind resistance does go up, but your engine also gets to operate more within its power band. With the right gearing, you can stay within the optimal RPMs and be close to the design power level of the engine at a reasonable cruise speed.

Empirically, I've driven big heavy cars fast for long distances, and gotten reasonable fuel economy; especially big German cars with big diesel engines. What kills them is stop and go, or when you have a smaller car with, say, 5 gears, and you are running it at redline to keep your desired speed.

What is awesome about electric cars is you could get much more efficiency in the motor across a range of power levels, plus regen. What is not at all awesome is the power density of lithium ion batteries.

Re: Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

#95

Post by r00fus »

grecy wrote: post #57
sliverstorm wrote: post #52

Earlier quoted context omitted.

The side of history that can't afford a Tesla S anyway. Small-minded of me, I know.

> The side of history that can't afford a Tesla S Yet. There were millions that couldn't afford an automobile when they came out too you know..... Give it time, stop thinking a new product has to be everything to everyone so early on.

Range is a significant factor of the Tesla's cost, and it'd require a order of magnitude of efficiency increase to both support a cheaper model while also keeping the same charging range and keeping Tesla's profit margins in place.

Re: Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

#96

Post by omegant »

digikata wrote: post #35

It's too bad you couldn't just hitch a secondary external battery pack to a mini-trailer hitched to the car for long distances. Roll into a station, unhitch the pack, swap for charged one, go on your way maybe 15 min later. I know there are proposals for swappable internal packs, with automatic swap machinery at the station, but a trailer hitch and external plug requires a lower capital investment, and is much less i…

Or for reaching the distant city a gasoline generator in the small trailer. Making it a plugable hybrid.

Re: Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

#97

Post by grecy »

gutnor wrote: post #69
grecy wrote: post #39

Earlier quoted context omitted.

People said exactly the same thing when the automobile was introduced and it was horribly less convenient than a horse and cart. Of course a new tech is slightly less convenient out the outset, and of course it will only appeal to a certain percentage of the population, and of course it will get better over time. Which side of history are those people on? Which side of history will you be on?

The thing is it was more inconvenient than horse and cart for a long time. ( Early cars broke all the time, costed a fortune and you needed to maintain it yourself - that was basically a toy for rich kid to parade at the country club ) You get absolutely no benefit other than bragging rights for being an early adopter. I understand that early adopters are damn useful, especially for all the startup creator here on HN…

> You can buy a regular car today and an electric one next time; it is not like electric car makers will refuse your business

Precisely. So people need to stop complaining the Tesla S doesn't meet their needs. Wait until it does, then buy one. If it never does, don't buy one, and don't complain about it.

Why is it so common for consumers to complain when a popular company makes a product that doesn't precisely fit their needs?

I personally am happy when I have no use for an expensive product, as it means I don't have any desire to spend money on it, and my $500 car will continue to meet my needs.

Re: Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

#98

Post by toomuchtodo »

atourgates wrote: post #89
TallGuyShort wrote: post #3

>> provide 170 miles of range in a 30-minute charge That would have still sounded impractical to me when I was still able to just drive through the night to get where I needed to be. Now that I travel with a young baby and a dog, that's about how often and for how long I have to stop for breaks anyway. This is impressive progress anyway, but I'm especially impressed now that it really wouldn't alter my own schedule m…

Just doing some quick numbers (not related to current specific locations of quick chargers and gas stations), stopping 30 minutes every 170 miles would add a bit over 6 and a half hours of stopping to a LY->NYC trip. LA -> NYC is about 2,800 miles. If you had to stop for 30 minutes every 170 miles, that'd be 16.5 stops, for a total of about 8.25 hours of charging stops. If you assume 25mpg in a car with a 12 gallon t…

I just drove from Chicago to Tampa, stayed for two weeks in FL, and then drove back over the last two weeks. I did both sprints straight through in a 2008 Infiniti G37, which has a six-speed auto, V6 engine, and 20 gallon tank. At an average speed of 85 mph, the car averaged about 24mpg, giving me a range of around 420 miles per gallon (with ~60 mile reserve).

This is an edge case of course. I'm 31, and drove the entire ~15 hour drive at once with breaks only for fuel/bathroom at the same time. If I owned a Model S, I'd just fly.

Re: Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

#99

Post by DEinspanjer »

umsm wrote: post #61

Is it reasonable to buy a Model S now hoping that within 6-7 years you can swap out the "old" tech batteries for newer / better / faster / higher capacity battery packs which will be introduced in 5-7 years? If so, it wouldn't be a bad long-term car for those of us who like to keep cars more than 5 years.

Yes. The cars were designed with that sort of future compatibility in mind. That is how they were able to implement and demonstrate the battery pack swapping station. While I personally don't believe there will ever be as many battery swap stations as there are super chargers, it is quite believable that in 5 to 10 years I'd be able to drive somewhere and swap out my aging battery pack for a new one that will have a higher capacity than what my original pack had when new.

Re: Tesla Completes L.A.-to-New York Electric Model S Drive Chargers

#100

Post by abalone »

atourgates wrote: post #89
TallGuyShort wrote: post #3

>> provide 170 miles of range in a 30-minute charge That would have still sounded impractical to me when I was still able to just drive through the night to get where I needed to be. Now that I travel with a young baby and a dog, that's about how often and for how long I have to stop for breaks anyway. This is impressive progress anyway, but I'm especially impressed now that it really wouldn't alter my own schedule m…

Just doing some quick numbers (not related to current specific locations of quick chargers and gas stations), stopping 30 minutes every 170 miles would add a bit over 6 and a half hours of stopping to a LY->NYC trip. LA -> NYC is about 2,800 miles. If you had to stop for 30 minutes every 170 miles, that'd be 16.5 stops, for a total of about 8.25 hours of charging stops. If you assume 25mpg in a car with a 12 gallon t…

There's one more factor: driving speed. To get more energy efficiency on long trips, it often makes sense to drive the model s around 50-55mph rather than 65+. So if you average 10mph slower over 2800 miles, that's an additional 8 hours of driving time on top of the charging time.

See comments here for a recent cross-country trip. Where the driver notes his average speed it's around 50-55mph. http://www.teslamotors.com/forum/forums/heading-cross-countr...

(Also of note: planning around cold weather seems to be a significant consideration.)

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