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The Tesla Roadster goes more than 200 miles (380 km) on a single charge. The average person drives about 40 miles (60km) in a day. This leaves a range of about 160 miles (257km) after an average day of driving in a Tesla Roadster. Meaning that at the end of the day when a Roadster is plugged in to be charged up, it is really only to top off the battery.
Why is this significant?
It is important to understand the amount of energy a battery draws when charging and how this affects the electricity grid.
The typical home is allocated 100-200 amps from the neighborhood’s transformer. Say an electric car is charged from a 50 amp (32 amp in Europe) circuit breaker. This is only 50 amps of the allotted 100-200. And if charged at night, not much other electricity is being used in the house. When charging a Tesla Roadster, the car only draws as many amps as are available. Once plugged into a 50 amp outlet, the car only draws 40 amps (due to the National Electric Code (NEC)). And drawing 40 amps is drawing 40 amps, be it an oven or electric car. A home can’t draw more amps than it is allocated. Utilities are well informed of the maximum amperage of any given home, and the homeowner may not make any changes to the service without appropriate permits and approval by the utility.
With that, many utilities require they be informed when a person purchases an electric car, and often the billing rates are modified to accommodate the electric car. This also gives the utility the opportunity to make sure that the house and neighborhood transformer are appropriate for the electrical needs. In fact there are forward looking utilities working with Tesla to learn of the charging needs of a typical electric vehicle and its owners. Here at Tesla we are seeing a very positive response from utility companies who want to work with us to continue to make electric cars a positive impact on our society and environment.
And lastly, the convenience of an electric car. A great time to use energy is during off peak hours. Not only is there a surplus of cheaper electricity, it’s also quite convenient. Much like how the Tesla Roadster is set to a specific amperage, when the driver comes home at the end of the day, the charging can be set to begin at a specific time, automatically. Tesla owners simply drive home, plug in the car and set it to begin charging during off-peak hours. In the morning, the car is ready to go with the equivalent to a full tank of gas, without ever stopping at a gas station!
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This would have been a better article if it had included some stats on actual average charging times/day from customer data. But then, I guess that would probably turn into an engineering blog…
Just out of curiosity, how long do the batteries stay charged if not plugged in every time one leaves the vehicle? In other words, would one be required to plug the car in basically every time they get out of the car?
re: How long the batteries stay charged, when it was raining a bunch last week, I left mine unplugged for a five days to see if it drained at all, checking every day. Unlike my laptop which loses about 1% an hour, there was no noticeable drain. If I remember right, it went from 176 remaining to still over 170. I think it may depend on temperature - if it were the summer, there would be more electrical usage to keep the battery cool.
The battery loses its charge fairly slowly. It will take several weeks to discharge completely. So there’s no problem if you forget to plug in occasionally. That said, Tesla recommends that it usually be plugged in so that the battery can be maintained at an optimal state of charge and temperature.
I think Lucas means “what is the discharge loss of the batteries used in the Tesla?”. I expect they’re very low, neglectable discharge.
I would like to ask if the cars provide a “charge scheduler” to make the car aware that the driver does not wish to use electricity during peak times/cold/hot weather, when the electricity is more expensive. In my country electricity is at a fixed price, but may be interesting for North Americans I think..
To Lucas: The amount of discharge depends mainly on the state of charge. The Roadster’s manual mentions from fully charged a loss of up to 7% per day, and up to 50% in the first week. After that the rate slows to about 5% per week. Extreme temperatures would change that. Users in colder climates have noted that the battery pack has a lot of thermal inertia.
- Alfred
There is indeed a charging time scheduler. Very simple, actually: you just specify the time of day when you want the charging cycle to begin. Of course, you can override that and force the charging to start immediately when necessary.
Question. Are the battery packs removable, and if so, when will “battery pack swap stations” make an appearance?
We’d like our EV to have unlimited range, otherwise, the times we plan to drive beyond he range of the EV, we would need a “second” conventional petrol vehicle stored for that sole purpose. That’s a waste of space and money if we’re only needing to use the petrol vehicle once a month, but there isn’t an EV solution to driving long distances, so swap stations seem like the logical compliment.
If “swap stations” owned the battery cells, then they could charge drivers a monthly lease fee “plus” a fee every time the pack is swapped. For consumers, their EV’s range would be “unlimited”, they wouldn’t need to plan time at night for recharging (we barely have time to cook dinner!), and they wouldn’t need to inform their power company they had an EV. For swap stations, bulk rates could be negotiated with electricity suppliers and those savings retained as profits, or passed onto consumers.
There’s a lot of work that’s going into developing these EV’s but no one seems to have spared a thought about infrastructure for “consumer convenience”. If consumers could visit battery swap stations, just as they do gas stations, then switching from petrol to EV will not be at the expense of convenience, or the added cost of needing a second petrol vehicle for long distance excursions.
If EV developers created a standard battery pack design, like a USB stick, that could easily be removed from beneath the vehicle, then swap stations could also be entirely automated. We would buy an EV tomorrow if we could do away with our petrol vehicle, and we would buy an EV if we didn’t need to spare a thought about plugging it in at night, and we would buy an EV if we didn’t need to worry about how far we might drive to escape City life once a month.
50% per week? I believe the original Roadsters had the battery coolant pump run continuously (24hr/day) and this accounted for most of the battery drain. This has been fixed.
It is also about the “charge scheduler” on the vehicle. I am curious how it will affect the battery life if the charge is not “scheduled appropriately”?
To J.Ryan: A suggestion for those long trips: Lease a gas car rather than have one sleeping in your garage for months at a time. A gas car is the ideal range extender for the next 20 years… And you’ll stil be doing 95% of your trips on electric.
Also, I believe the time, effort and money required for swapping stations is ridiculous, the main danger being of replacing a petrol monopoly with a battery leasing/charging monopoly (i.e project better place). The technology on batteries is advancing so fast those swapping stations would be obsolete before anyone even started using them.
John Ryan: The Tesla Roadster battery pack wasn’t designed for swapping, replacing it would be like replacing the engine in a gasser. The upcoming Model S has a bottom mounted battery that is designed for quick swapping, though obviously battery swap facilities will have to be built. Tesla is also developing public “45 minute” charging facilities for the Model S, so a future road trip might include a stop at a roadside diner with a “park & charge” lot - plug in the car, go have lunch, and in less than an hour both you and the car will be ready for another 200 to 300 miles.
Plugging in at home will only take a second, and for local driving would be a lot more convenient than going out of your way to a battery swap facility. That “at home” convenience beats old fashioned gassers by a wide margin!
I would take Anthony’s last sentence a step further. The 244 mile range has not changed for about three years. Mr Musk has repeatedly stated the battery technology is advancing 10% a year. The math would suggest: 244×10%=268; 268×10%=295; 295×10%=325 miles. Three years is a long time for the same battery. I would wager a “new and improved” battery for the Roadster sometime during 2010 with a range of at least 325 miles. Have you read what is coming out of Colorado State U.? Scientists from numerous labs around the globe are working with nano technology. The hope/promise of the 10X battery (lap tops going from 2 hours up to 20 hours) for EV would be a serious threat to the ice and EXXON/OPEC. It is going to happen it is just a matter of when.
CM;
To add your comment: 45min is for 80% of the battery full capacity. For 300 mile battery that would be 240. OTOH, for 400 mile trip you could drive 200 then charge for that another 200 miles, which means that you have 100 miles in battery pack. That means you need only 100 mile worth recharging. If 240 takes 45 minutes, then 100 miles takes 45/2.4 = 18 minutes 45 seconds.
I can’t eat a decent lunch that fast. Some fast-food restaurant where you get your hamburger immediately you might be able to eat it before your car has recharged itself, but you need to be quick. That’s too fast, we absolutely need to make it slower ;-P
Seriously, that 45 minutes is really fast enough. You would need to take one break in your driving when driving longer than 300 miles, but at least I would do that anyway. 300 miles straight driving 60mph average speed (which is actually quite fast for average speed) is five hours. No matter how good car you have you might want to stretch your legs for few minutes and take a leak before continuing.
What that needs is that those service stations with that kind of chargers actually are build here and there. Because you drop over 90% of gas-station customers and electricity doesn’t cost quite as much you can’t expect to get profit from charging alone (unless you charge unreasonably high price for that service), so you need to generate your income from other sources. That means restaurants and other that sort of things. Those charging points would be there only to lure customers in.
Good thing is that, once installed, those charging points wont lose you practically any money because they would have very low maintenance cost. Basically it is just a smart wall socket. If you don’t use it it happily just sits there doing nothing. So if you get installation cost for those charging points low enough, they will appear everywhere. If not, then we might have a problem.
Snapshot of the future electric car on the smart distriduted grid…with Tesla and the Roadster an a primary impetus.
If average person drives 40 miles / day and there are 250 million cars in US you can count how much electricity that would take.
40miles is about 1/6 of Roadster battery pack. If you count charging losses in that counts about 10kWh
250M * 10kWh = 2500 GWh/day. For one hour that is about 100GWh. Quite a lot. That’s about 200 500MW power plants worth extra juice you need in the grid.
Of course that figure is only in that direction. I’m guessing that “40 miles / day” is not for /car or even /person count, I believe it means that _if_ you drive at all you drive average 40 miles.
Waht are the typically amount of watts used for a charge. i am sizing a Solar PV system. I need that info times my expected mileage using a Tesla range of 240 miles.
Timo…
You made some HUGE assumptions! That do not reflect even a remote possibility.
That 250 million cars will ALL draw their needed 10kwh (40 mile range) from the grid during the same exact time?!?
And will try to get it all within 1 hour during that time.
Reality Check:
It will take 20 - 25 years before there are 250 million EVs on the roads.
Do you not think that many houses will supplement their grid energy with rooftop solar or wind?
Do you not think that in 20 years there will be a “Smart Grid” that interfaces with V2G enabled car chargers? And will span from coast to coast.
Cars will typically be “plugged in” during the 7pm thru 7am time frame. Charging will be done when the grid allows it to charge (with considerations to SOC and user needs).
7pm EST = 12am midnight GMT (the earliest time for a typical charge start)
and
7am PST =3pm GMT (the latest time for a typical charge end)
Total range of typical plug in times = 15 hours
With a 12 hour window spanning 4 timezones, that gives the smart grid 15 hours to spread out the entire country’s charge profile.
So your 100GW becomes 6.67 GW! And if a typical power plant provides 500MW, then 14 new plants will need to be built.
If we average 1 (500MW) power plant every 17 months then we can match the growth easily!
Paul Verchinski;
That depends of the charger you want to use. Look at different charging solutions at the main page.
www.teslamotors.com/electric/charging.php
For example home connector has max output 16.8 kW
Paul,
You can generally assume that you can go between 3 and 4 miles on a Kwh of electricity in real-world driving. The difference depends on how fast you drive and how much heat and a/c you use.
@Timo: Because much more electricity is used at some times of day than at others, there is a lot of spare capacity outside the peak periods. This is why charging electric cars overnight makes so much sense. It’s particularly good for wind, wave, tidal and to an extent nuclear generation, because you can’t switch the wind off and store it when it is not needed, like you can with coal. So as more power comes from those sources, off peak prices will fall further.
It will soon be possible for car chargers to get signals from the grid telling them how busy it is, so they can switch off if there is need elsewhere for power, and switch on when there is spare power around. If you set your car to charge overnight, you will still have a full car in the morning, but it would have charged different amounts at different times of night depending on when the grid was cheapest.
Paul
The Roadster has a 53KWh battery and that lets it go 244 miles. That works out to about .217KWh/mile. How far do you drive per day? If you drive 50 miles that would mean you need a minimum generating capability of 11KWh. Assuming perfect efficiency of 200 watt panels and 4 hours of good sunlight per day wouldn’t that be 12KWh (added one for a margin) divided by 4 hours. So 3KW needs to be generated per hour. So what does that work out to? Fifteen 200 watt panels? Add a couple panels for efficiency losses, cable length, etc. Unfortunately I think you need to convert the DC power from the panels to AC to feed the car. I don’t recall seeing the ability to charge off DC, but I could easily be wrong. Most inverters are going to lose at least a couple percentage points on the conversion.
The previous engineering blog by JB Straubel that was posted December 22nd, 2008 has some nice graphs that illustrate energy consumption per mile. Those, combined with your knowledge of your driving habits, location and your intended solar design, will hopefully help you refine the crude guesses I have in the previous paragraph.
Joe G, you actually managed to make it worse.
That 100GWh was for one hour average spanned to entire day, for entire day that was 2500GWh. If you drop half a day off that figure you basically double energy need for rest of the day. So for peak charging time energy consumption is not 100GW it is 24/15=1.6 times more= 160GW.
Of course that is attainable, but it is a lot. No matter how you calculate it.
I also believe that this 40 miles / day is not in reality / day, but average _use_ of the car is 40 miles _when_ car is used. That can drop this figure a lot.
Robert (Jamie) Munro also has a good point that there is a lot of unused capacity in the grid that can be used to charge cars, so additional energy need is not quite that big. I however still believe that it is quite a lot.
(BTW, Robert, you can’t shut off coal plant very fast, it actually takes more time than shutting off nuclear plant)
Rooftop solar panels, smart grid and stuff like that help, and also the fact that this transition wouldn’t happen over night so we have time to build infrastructure for them. Not much time though. EV tech is advancing faster than grid is developing. It might be reality that grid-based electricity simply isn’t enough for all of those EV:s soon. I also don’t give you 20-25 years for that change. Cars don’t last that long, and I predict that within about 10 years every new passenger car is an EV, possibly sooner. You will have almost all cars based on EV tech within 15 years.
Even now these new Tesla batteries would allow Roadster to have way over 300 mile range, and those are not yet based on those high tech techs that you can read from scientific sources like Journal of Power Sources. What you can find there would allow Roadster to have over 2000 mile range with battery of that size. When you reach 600 miles with single charge nobody no longer buys gasoline cars.
OTOH It might be possible that we have clean fusion pretty soon. Check www.focusfusion.org/. If that gets ready soon that would be clean and basically unlimited energy source. Also that reactor is small compared to Tokamak-reactors. So small that you could have several GW reactor in a apartment basement, and not in some distant huge power plant.
Paul;
Figure about 70 kwh, of which 55 kwh actually gets stored, with the rest being losses. That’s for a full charge from zero. I doubt you’d have to do that very often. Figure about 290 wh (0.29 kwh) per mile driven.
Timo;
Glad to see you’ve checked out Focus Fusion. Drop in on the forums; we’d be glad to hear from you!
For those apartment buildings, each generator is expected to run at around 5MW, so I doubt you’d need more than one per apartment!
John Ryan asks about long distance travel. That was worked out in detail years ago by ACPropulsion.
See the ‘Long Ranger’ trailer .
en.wikipedia.org/wiki/AC_Propulsion_tzero
web.archive.org/web/20020124085803/http://www.acpropulsion.com/
(Note the trailer behind the RAV4 EV)
web.archive.org/web/20020204171625/www.acpropulsion.com/Products/Range_extending_trailers.htm
(Note the ‘BackTracker’ mechanism)
Seems to me this would be something you could just rent as needed …
Every reference to Tesla cars called them a “Hybrid”, when of course they are All Electric on the Yahoo Car slideshow summary in Detroit, Michigan, January 12, 2010.
-> ca.news.yahoo.com/nphotos/Auto-Shows/ss/events/tc/20070913_autoshow;_ylt=AupWbfPURlOm6Naigw7reY59l80F#photoViewer=/12012010/6/photo/photos-n-news-ceo-product-architect-tesla-motors-musk-stands-model-s.html
Paul Verchinski : The home recharger designed for under 4 hour charging uses 240 volt 70 amp power, which is 16,800 watts. However, unless you do your charging in the daytime, it is unlikely to be directly powered by your solar panels. Instead, it would draw power from the electrical grid (with a grid tie system) or from storage batteries (if you are “off the grid”).
Don’t confuse “Power” which is the rate of electricity flowing at any instant in time, with “Energy” which is the total power flow added up over a period of time. Electrical power is measured in Watts or Kilowatts (1,000 watts). while electrical energy is measured in Watt-Hours or Kilowatt-Hours (1,000 watt-hours).
Don’t decide on the solar power system size based on just one electrical item, it is better to take into account the average daily energy consumption of the entire household. Also take your budget into account - don’t spend more than you can afford.
Brian H;
That “several GW reactor” (which should have said “several MW reactor”) did mean single reactor with several MW output.
I wonder how small those can be made. Small enough to fit under the hood of the big long range truck? Unlimited range with MW -class power output would make current trucks look like children toys. Fast trains without external electricity source. Maybe even space-applications. Vasimr -rocket with serious power.
What has been the oil and car industry’s response to this (in my opinion) awesome developement in high performance pure electric cars? I saw the documentary, “Who Killled the Electric Car” and became curious if oil companies and car companies still look upon these new developements as threatening to their revenue instead of a perfect opportunity to free ourselves from the dependance on oil. Have Tesla Motors seen any opposition from these industries in these current years? Do you think the EV industry will one day becaome as big or bigger than gas powered cars?