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The Unofficial Tesla FAQ

The Unofficial Tesla FAQ

Contents


Glossary

Q: EV, BEV, PHEV, FCEV, ICE, ESS, Li-ion? What's with all this alphabet soup?

  • EV = Electric Vehicle
  • BEV = Battery-Electric Vehicle
  • PHEV = Plug-in Hybrid Electric Vehicle
  • FCEV = Fuel Cell Electric Vehicle (usually powered from hydrogen)
  • ICE = Internal Combustion Engine (including gasoline, diesel & biofuels)
  • ESS = Energy Storage System (i.e. the battery pack)
  • Li-Ion = Lithium-ion cell

Pollution

Q: Electricity is generated from fossil fuels! Aren't you just moving the pollution somewhere else?

EVs are inherently more efficient than ICEs. As a result, the carbon dioxide emissions are slightly less even if your electricity is generated from coal-fired plants, which is the dirtiest way we have to produce electricity. If you bring other electricity sources into the mix, the numbers get better. Few regions are powered from 100% coal.

It's true that we need to clean up our power grid nationwide, or indeed globally. Electric cars will benefit from that process -- we can move the power grid to more nuclear, or wind power, or geothermal or solar power, and our electric cars won't have to change.

Also. . . Even if you are burning only coal for electrical power, and it's nearly as polluting as gasoline, it's still reducing the need for imported oil and helps ease the problem of global oil depletion.

Trivia: This argument is sometimes called 'The Long Tailpipe argument'.


Grid Capacity

Q: We're already having brownouts and rolling blackouts in the summers! If everyone switches to electric cars, won't the power grid melt down?

According to the US Department of Energy, the nation's existing power grid could support as many as 180 million electric cars. The cars would charge at night (via simple timers) when electrical power demand is low. Today we have power plants often "idling" at night, producing unwanted power because it wouldn't be practical to shut the plants down and restart them every next morning.

As for the Roadster. . . The standard charging unit comes with a timer, so you can have it charge at night. Tesla Motors are planning to produce somewhere around 1,500 of Roadsters per year. Even the upcoming Model S is slated for perhaps 10,000 units per year. Clearly they won't be testing the DoE's 180-million-vehicle estimate any time soon.


Engine Noise

Q1: Real gearheads love the loud, roaring engine sounds of their cars. How can you get them to accept something totally silent?

First up, it's not totally silent. When accelerating the motor produces a turbine-like whine that some have described as powerful, purposeful and futuristic. (One reporter likened it to the Millennium Falcon about to jump into hyperspace.)

Decades of driving ICE-powered cars have conditioned drivers to expect loud engine noise and often judge car engines by the sounds they make. Changing their way of thinking might not come easily -- particularly for those who derive a perverse pleasure from waking up the neighborhood. Their neighbors may be glad to see more electric cars on the road.

Q2: Silent cars are dangerous, you can't hear them coming!

Tesla Roadster is not the first very silent car. Such cars have been among us for a long time. If they were really any more dangerous than ordinarily loud cars, that would show in accident statistics. For example, Toyota Prius is capable of low-speed electric driving and is thus very silent at low speed:

The National Highway Traffic Safety Administration held a hearing in Washington DC June 23, 2007 to gather the facts and data. It turns out that in spite of having over 500,000 Priuses in the USA starting from 2000, there is no accident data showing an unusual risk to pedestrians. The Prius has the same pedestrian accident rate as ordinary gas vehicles.

Source: www.regulations.gov, document NHTSA-2008-0108-0020


Battery Life

Q: My laptop battery died after two years! How can you expect anyone to buy a car with a battery that needs replacing every couple of years?

It will last much longer than two years. The battery in your laptop has no cooling system, is located next to hot electrical components, is often kept at 100% state of charge for long periods of time and then completely discharged until empty. These are the worst possible conditions for Li-Ion battery life. The Tesla Roadster has a liquid cooling system, and it has a monitoring system that controls the rate of charge and the charge level to extend the battery life. It should be good for about seven years, possibly even ten.

The battery doesn't lay down and die after seven years, it gradually loses capacity from the moment it's manufactured. Seven years is merely an estimate of when most people will want to replace it. If you can tolerate the reduced range, then you can further stretch out the replacement time.


Exploding Laptops

Q: I heard about laptop batteries that exploded! If you crash a car full of those things, won't it be a disaster?

There have been FIVE instances of laptops bursting into flames. Every day dozens of gasoline-powered cars catch fire, but it doesn't make the news. Gasoline is far more volatile and dangerous than lithium-ion cells. The Tesla Roadster's ESS has been designed to contain any fire that breaks out, so if a single cell fails it won't start a chain reaction. The Roadster has been through a crash-testing regimen with live battery packs on board. None of the cars caught fire.


Battery Disposal

Q: How can anybody possibly call this car "green" when they're eventually going to have 900 pounds of highly toxic batteries to dispose of?

Unlike most other chemistries, lithium-ion cells aren't considered toxic by the EPA. By way of comparison, used motor oil is considered toxic. As far as the EPA is concerned, you could dump your old battery into a landfill, it's not a problem. However, it wouldn't make economic sense to do that, because they can be recycled and valuable materials can be recovered from them. Before any cars have been delivered to customers Tesla have already made arrangements for recycling their worn-out batteries.

Suggested reading: Mythbusters Part 3: Recycling our Non-Toxic Battery Packs


The People's Car

Q: It's $100,000 and only has two seats! What we need is a $20,000 car that seats five. Why are these Tesla guys making a toy for the rich instead of something we all need?

Why are Ferrari and Lamborghini making toys for the rich instead of something we all need? Maybe they think they can turn a profit at it.

The history of EVs is littered with failed companies that tried to save the world with their first product: a "people's car" that just about anybody could afford and just about nobody wanted. Gasoline was cheap and plentiful, global warming was a fringe issue, and BEV technology wasn't ready to compete head-to-head against gasoline.

Tesla aren't ready to produce a "people's car" yet, but they are building a a car company that will be able to offer one when the time is right, when the technology and marketplace are ready to support it. They are already designing future models with greater passenger capacity and lower price points (Tesla Model S).


Battery Replacement Cost

Q: I heard that the batteries in the Roadster cost $30,000! Somebody else said they're $50,000! How can anybody afford to replace them after five years?

Tesla have not officially said how much the battery cells cost them. The most credible estimate seems to be around $20,000 to $30.000 per car. If commodity cell prices continue to fall as they have in past years, the replacement cost should be closer to $12,000 by the time the first ones are due for replacement.

And yes, that's still a lot of money. However, it doesn't compare that badly with the maintenance costs of other exotic sports cars. Also, it's likely that the replacement ESS will be further improved and will have longer life and better performance than the original.

Tesla Motors now offers a battery replacement program that allows a customer to pay up front and in return receive both a significant discount and certainty about the battery replacement cost. The price of this replacement program is $12,000 and is available to all Tesla customers, including those that have already taken delivery of their car.


Lotus Elise Comparison

Q: How can you justify a $100,000 electric Lotus Elise? For that money I could buy two Elises and have money left over for gas!

The Roadster is not an Elise, they have different characteristics and different purposes. The Elise is a spartan, super-lightweight sports car with an emphasis on track performance. The Tesla Roadster is heavier and less specialized, but more livable, more luxurious, can accelerate harder, and has all the unique advantages of an electric power train. It should be able to hold its own against exotics costing much more.

The Roadster is, in fact, the least expensive car you can get with a carbon-fiber body.

Suggested reading: Mythbusters Part 2: The Tesla Roadster is not a Converted Lotus Elise


Performance

Q: So the top speed is what, only 130 MPH? And you're calling it a supercar?

Tesla Motors is calling it a supercar and it's top speed is electronically limited to 125 MPH.

However, this car isn't made for the race track, it's intended primarily for public highways - and going faster than 125 MPH on the highway doesn't make much sense. Engineering the car for higher speeds was not considered a priority. It would have presented some challenges in terms of battery power density, heat dissipation and gearing. And the range at those speeds would be much much lower.

The driving characteristics of Tesla Roadster aren't quite like anything you've experienced before. The electric motor produces maximum torque of 375 Nm (276 ft/lb) from zero RPM to 4500 RPM (from 0 to 40 MPH). Max power of 185 kW (248 HP) is reached at 5000 RPM and lasts to 8000 RPM (from 40 to 75 MPH) after which it gradually declines down to 105kW at maximal 13.500 RPM (125MPH).

Real-world performance

Acceleration from a standing start should thus prove to be violent, if not brutal. You always have instant power on tap, there is no "turbo lag", for example. In short, the performance in the areas where you do most of your actual driving are outstanding.

As Tesla Motors started the production of Roadsters, they found some unforeseen problems with power electronics. To avoid them, they reduced the maximum acceleration of first few hundreds cars (model year 2008) down to about 4.1 seconds from 0 to 60 MPH. Those problems were solved with firmware updates and some electronic modifications so cars produced from second half of 2009 onward (model year 2010) will reach 60 MPH in advertised 3.9 seconds. Roadster Sport having hand-wound motor and some additional performance optimizations will reach 60 MPH in 3.7 seconds.

Tesla Roadster has air-cooled power electronics and electric motor. During prolonged hard driving their temperatures could rise above safe limits. If that happens, controller automatically limits maximum power to about 100kW which causes maximum speed to drop to about 100 MPH and acceleration is not that aggressive anymore. When electronics manages to cool below the limits old capabilites return.


Range

Q: How far can it go on a charge? First they said 250 miles, now they are saying only 200. What next?

Those numbers were all preliminary projections. The final, official EPA numbers are:

  • 231 miles EPA city
  • 224 miles EPA highway
  • 227 miles EPA combined (city/highway)

Everyone should be aware that these official EPA-rated driving ranges are still only estimates, and that the actual results for owners will depend on things like: the age and mileage of the car's ESS, the passenger and cargo load, hills, weather, traffic and speed.

The other thing to note is that Tesla Roadster comes with different characters to choose from. Those numbers above were reached in "Range mode". In this mode the car charges up to 100% (battery completely full) and while driving it allows to be discharged to a very low level (battery almost completely empty). Doing this often is bad for battery life thats why you'd normally put the car into "Normal mode" where it will only charge up to 90% and won't allow to be completely discharged. Doing this will prolong battery lifetime, but will reduce the maximum range in this mode to somewhere around 200 miles. Early customers are getting from 140 to 180 miles of real-life mixed highway and hill driving.

As they say, "Your mileage may vary", literally.

Source: Official Tesla Roadster FAQ

Trivia: Tesla roadster goes 241 miles on a single charge - while rallying


Cold Weather

Q: Won't cold weather reduce the driving range to, oh, I dunno. . . let's say about five miles?

No. Lithium-ion cells perform better than most other chemistries in cold weather. If it is really freezing, the car may be a bit sluggish at first, but the cells should soon warm up to operating temperature. Depending on conditions, the range might suffer somewhat, or it might possibly gain as a result of the cooling system not having to work as hard.

The cabin heater also draws a fair bit of power (1500 watts), which would impact your driving range. A quick calculation suggests running it continuously for an hour might take about seven miles off your range. However, the Roadster comes with heated seats which consume much less power (60 watts) - they should have negligible effect on range if you rely on them instead of the cabin heater.

One nice thing about the cabin heater is that it will put out heat immediately, there's no need to wait for the engine to warm up, as you would in a conventional car.


Daily Driving

Q: Wouldn't I be nuts to own a car that conks out after only 200 miles and then has to be towed home?

If you habitually drive more than 200 miles per day, then yeah. . . the Roadster -- as your only car -- would be a bit of a nutty choice for you. Many people don't drive that much on a daily basis, and it's unusual for anyone to buy an exotic two-seater sports car as their one and only car.

Remember too that you'll be plugging your car into the charger at night and start every morning with a full charge. This will work for a lot of people.


International Sales

Q: I live outside the USA, will Tesla sell me a car?

If you're from Europe then you can already order one. Other parts of the World will have to wait a little more.

Tesla Motors is a startup company and their production capacities are limited. They are stretched thin covering the USA and Europe. They want to expand to international sales when their resources allow. It may be a few additional years.


Regenerative Braking

Q: Why can't they connect a generator to the wheels, and use it to recharge the battery, and drive the car for free?

All that energy came from the battery. It doesn't make sense to use the battery to charge itself -- that would be like perpetual motion. However, the Tesla Roadster does use regenerative braking. When the car slows, some of the energy is recovered and put back into the battery, and it extends the driving range.


Solar Panels

Q: Why can't they just put a solar panel on the roof of the car, and drive the car for free?

It wouldn't be big enough, it wouldn't provide enough energy to be useful. If you left your car parked outside all the time, maybe it could collect enough charge to go a few miles per day. Most of us would prefer not to leave a $100,000 car exposed to the weather all the time. Plus, you'd be needlessly hauling around the weight of the solar panels.

Putting larger solar panels on the roof of your home, garage or carport makes a lot more sense. Tesla are planning to offer a rooftop solar option which is good for about 50 miles of driving per day.


Wind Turbine

Q: Why can't they put a wind turbine on the car, and use it to recharge the battery, and drive the car for free?

If you're talking about using wind generated by the car's motion when driving, then you are getting back into the perpetual motion problem: all that energy came from the batteries to begin with. To charge themselves, they would have to output more energy than they take in. No battery can do that.

If you're talking about a wind turbine that would charge the car while it's sitting parked, then you are back to the same problem that solar panels have, because it wouldn't collect enough wind power to do anything useful.


Battery Exchange Schemes

Q: I had this great idea! The batteries could be designed so you can swap them easily, and there could be stations along the highway where you could pull in and get a fresh battery. . .

Yes, are you the 543rd person to have that idea. In fact, quick-change batteries were used successfully in the Formula Lightning racing series. However, there are some practical reasons why Tesla aren't going that way.

The ESS weighs 900 pounds and has a liquid cooling system, and it operates at high voltages. Designing equipment to quickly, safely and reliably change it without losing coolant, and without adding excessive weight to the vehicle, would be a very tricky engineering problem.

More importantly, the batteries degrade with age and use. You wouldn't know the history of the battery being swapped into your car, and the station owner wouldn't know the history of the battery you are trading to him. There is a potential for abuse and scams. As well, the capital cost of keeping a stock of batteries on hand would be high. It's hard to build a business case around this when most people would be charging up at home most of the time anyhow.


Super Batteries

Q: I heard about some kind of super-battery with nanotechnology that's supposed to be a lot better. Why aren't Tesla using those?

There are new battery cell chemistries from companies like A123 Systems, AltairNano and others that appear highly promising. These cells were not available when Tesla began designing the Roadster, and they are still not available in bulk quantities at commodity prices. Both the A123 and Altair cells have lower energy density than the commodity Li-ion cells that Tesla are using, so range would be somewhat reduced.

Future models from Tesla aren't locked into any specific cell chemistry. They'll use whatever is available with the best price and performance. Battery research is advancing rapidly.


Charging Time

Q: I've heard those new super-batteries with nanotechnology can be charged in only ten minutes! Can the Tesla Roadster?

No. The commodity Li-ion cells used by Tesla can't accept a charge that fast. Even if the battery could take it, fast charging would require some very special -- and very expensive -- equipment to provide enough current. According to AltairNano, their fast-charging system requires 480 volts and 500-1000 amps of current. In comparison, the standard Tesla charging station draws 70 amps at 220 volts, which is about as much as you can reasonably get in a residential setting. This allows a complete dead-to-full charge in about 4 hours. It's still a lot faster than most EVs of the past.

Charging from a 50-amp RV hookup (using the Tesla portable charging kit) takes about six hours. Charging from a 110-volt outlet would take over 30 hours.

All this waiting comes into play only when the battery is really empty and you need to wait for it to charge up. Usually you won't be doing it this way at all so charging time looses much of its importance. Usually you'll arrive home with some charge left in the battery and just plug it in. Next day in the morning you'll find your car at full ready for another 200 miles or so. Owning an EV needs some mental adjusting, you treat it a little differently than a gas car.


Credibility

Q: I don't believe it! Can you prove any of this stuff?

Not all of it. Tesla Motors are doing a lot of things that are new so unforeseen things could happen.

We are all watching closely and time will tell. However, they've posted a huge amount of information on their website (where much of the info for this FAQ was gleaned from) as the cars have gone through development and testing, as well as the tours given to people who put down deposits for their cars. As of end of May, 2009, more than 400 customers have already taken delivery of their Tesla Roadster. They are already testing all these stuff in practice.

As they say, "The proof is in the pudding". Go to a Tesla store and ask for a test drive!

I guarantee you a Tesla grin! [:)]


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