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For owners who may be new or unfamiliar with the Tesla Roadster, I'll run through the basic information needed to preserve this rare and special vehicle.

The most obvious concern is properly maintaining the battery pack. If the Roadster is left unattended and without power for weeks or months, the battery back will slowly discharge until the pack is fully depleted. If this happens, the battery pack may be ruined. Even if plugged in, if power is interrupted by a popped breaker, extended outage, service disconnection, etc., permanent damage to the battery pack can occur.

Also of concern is temperature. The Roadster should not be left unplugged in extreme temperatures. If the battery pack gets hot, it should be plugged in so it can cool. Consult the owners manual for more information.

Charging

Level 1 In the United States and Canada, the Roadster can be charged at 120V with a simple cord sold as the MC-120. It just connects the car to power with no EVSE logic and the car assumes a 15A circuit suitable for charging at 12A. At this power level, the car can't run the full cooling system and in fact uses a lot of the power just to run the coolant pump. This means a slow rate of charge, and in fact in hot weather, may use all of the power just trying to cool the battery pack. In comfortable weather, not too hot and not too cold, and no rush to get charged, this can be an effective way to charge. Some owners used Level 1 exclusively. Since the coolant pump tends to run continuously, even after charging is complete, there may be a corresponding reducing in the lifetime of the coolant pump.

Level 2 charging means connecting to 240V single-phase power using an EVSE that communicates the maximum current draw allowed for the circuit. It uses the same communication protocol as standard J-1772 charging stations. Having more power means the battery pack can be better thermally managed, which can make quite a bit of noise when the fans, compressor and pumps are all going full tilt. The maximum charge rate of the Roadster is 240V/70A. Unless we were in a hurry on a road trip, we generally charged at 240V/32A which yields good energy efficiency and may be nicer to the battery.

The Roadster can charge from a standard J-1772 station with an appropriate adapter. Tesla sold one for a while and there's an aftermarket adapter.

Charge Modes

The Roadster has four charge modes, used for different purposes.

Standard Mode limits charging to the middle 80% of the battery pack, not letting the charge level get too high and warning the driver, and even shutting the car down, before getting critically low. This is the mode used for daily charging of a Roadster that's driven locally with some regularity.

Range Mode opens up the full charging range, allowing a higher state of charge and enables driving down to a lower start of charge. Range mode also limits power from the pack, and thus reducing maximum acceleration in the name of extending range. Occasional range mode charging didn't seem to have a negative effect on our battery pack, but charging frequently to the top of range mode may accelerate the loss of battery capacity. When we owned a Roadster, we'd do a full range mode charge at the start of long road trip, then switch over to standard mode for driving.

Performance Mode uses the full charging range, allows the battery to get warmer while charging, and allows maximum power (full acceleration). This is appropriate for driving on a track, but probably accelerates loss of battery pack capacity if used often.

Storage Mode displays the state of charge like Standard Mode, but will let the state of charge drop to around 30% then will maintain that level of charge. This is the best mode to use when the Roadster won't be driven for weeks or months. The car must be plugged in to maintain the health of the battery pack. The disadvantage of Storage Mode is that if the power supply is interrupted, it will start discharging from around 30%, so it will get into trouble sooner than if left in Standard mode. That's probably more of a concern if it's in long term storage and ignored vs. being kept for the winter in your garage where you'll notice of the power goes out or the breaker gets tripped.

An example charge screen:

The drawing below shows how to interpret the state of charge in the two main charge modes. Range values are for the original 53 kWh battery pack when new.

Vehicle Log

The Roaster maintains a detailed internal log which can be downloaded via the USB port in the console. Although the format of the logs isn't documented by Tesla, various owners have been able to decode and extra a great deal of data. The log file has two sections: a long term section that has basic info and a more detailed section of recent driving and charging. See the page on the VMSParser I created for more information.

Remote Monitoring

The Roadster did not have support for remote monitoring, not at all for the 2008 (v1.5) Roadster and nothing driver-accessbile for the 2009 and later (v2) Roadster.

There is an aftermarket system availble, the Open Vehicle Monitoring System or OVMS. OVMS allows for remote monitoring of charging, GPS tracking, custom charge settings, and viewing battery metrics. In addition to allowing manual remote monitoring, it can also send low-battery alerts and unexpected motion alerts if the car moves not under its own power.

More Resources

There are a number of other entries on the blog detailing our adventures with the Roadster, plus another collection of longer Roadster articles of practical and historical interest.

The Tesla Motors Club forum is the best community resource around, although its focus has natually shifted to the newer Tesla vehicles.

Nissan has done a poor job of communicating state of charge to LEAF owners.

The first problem with this display is that you can't tell where you are with a simple glance. Quick: how many bars are there? Imagine if only some are lit up, how long does it take to count them? Once you have counted the bars, you have to divide by 12, or multiply by 8.3%. Like I want to do that while I'm driving! There's a nice number there, 93 miles, but the problem is that number varies wildly based on how you've been driving. Your state of charge might be 40% but the range estimate could be 12 miles if you just reached the top of 4,000-foot pass, or it might be 80 miles if you have been descending from that same pass. Likewise for just getting off of a stretch of 75 mph freeway versus getting onto the freeway after a stretch of 45 mph urban thoroughfare.

Drivers need to know what's in the battery unfiltered by a rating on their recent driving.

This isn't just my opinion, or the opinion of a few old school EV fanatics. I keep hearing from new LEAF owners who after a few weeks of driving realize that the estimated remaining miles on the LEAF dash is not useful. It's not that Nissan did it badly, or that it can be fixed by improving their software, it's not what EV drivers need.

Ford is coming out with the Ford Focus Electric this year and is apparently asking for opinions on what drivers want to see on the dashboard.

First off, Ford should be asking what gas car drivers want to see and putting that in their ads, but they should be asking what experienced EV drivers want to see and put that on the dash. Ford should start with dropping a line to the folks at Plug In America.

When I'm driving, I don't want to see animations or flashy graphics in my main field of view. I'm not watching a movie, I don't need special effects, and I definitely don't need running commentary on my driving. The LAST thing I want to see on the dash is any mention of gasoline. Did the Model T need a gauge showing how many bales of hay had been saved?

Please don't let some gas-driving marketing intern design the dash for an electric vehicle based on talking to other people who haven't owned an electric vehicle.

My wife and I have been driving electric for three years and have logged over 38,000 electric miles. We've done lots of local driving and enough road trips beyond our single charge range that we know what we need.

What I do want to see, in order of importance, is:

1. Speed, preferably numerical, very easy to read at a glance, the biggest number on the screen.
2. After speed, the single most important information an EV driver needs is the state of charge, SOC. This should be conveyed as remaining charge energy, in numerical resolution comparable to a mile's worth of driving, and not mangled by some unknown function of my recent driving and road conditions.
3. Instantaneous energy use. This should be graphical and clearly show whether I'm using or generating energy and how much, even when it's a small amount. Having a number would be nice, but not necessary.
   
4. Trip meter, preferably selectable from several. Having a trip meter that automatically resets after each full charge would be cool, but we still want user-controlled trip meters.
5. Estimated miles remaining based on recent driving is rarely useful, but it would probably be weird to not have it available. Most people think that will be useful until they get used to driving electric. Not having it would be a distracting omission for new owners. It can be on the dash, even on by default, but there should be a way to get rid of it, perhaps making it an alternate to an absolute remaining energy number.

The purpose of showing the state of charge isn't really about figuring out how far you can drive with the current charge. The answer to that question depends on too many factors to ever be a meaningful single number on the dash. Instead, the EV driver needs to answer two simple questions:

1) Do I have enough energy to make it to my destination?
2) If the answer to #1 is "maybe", how do I need to moderate my driving to make it?

Most of the time the answer to #1 is an unconditional "yes". An answer of "no" means it's time to find charging, a condition that should be rare if the car is being used for local driving as intended. If the answer to #1 is "maybe", then I need the best information possible to answer #2.

Note that an estimated range is always wrong when it matters because it assumes my driving style and road conditions are going to remain constant. It's basically telling me how I have been driving. I don't care about that. I need the information that will make it clear how I need to be driving for the rest of my trip.

For this reason, the choice of energy unit for the SOC display is critical. I want something more convenient than kWh, something that will not require doing math to interpret the number. If a vehicle has a certain stated nominal range, which corresponds to X Wh per mile (battery-to-wheel), then the ideal energy unit is X Wh. Tesla calls this an "ideal range mile." Call it whatever you like, but it's a very convenient unit of energy as it tells me how much is in the battery and gives me a range goal I can generally meet or even exceed if I need to.

If a car has a nominal range of 100 miles, then SOC percent corresponds to one mile of nominal driving. That's cool, but it doesn't generalize very well. When next year's model has a range of 140 miles, I don't want to have to multiply SOC percent by 1.4 to get nominal miles.

Showing SOC as kWh is even worse. Not only do I have to multiply by some goofy factor, it's a different factor for every car depending on weight and aerodynamics. Showing kWh used as part of a trip meter is awesome, and showing SOC in kWh has a certain appealing geek factor, but I don't want that to be my best-resolution SOC unit.

We'll all be better off if the car companies start showing SOC as nominal miles now.


On the Roadster, an "ideal range mile" is the amount of energy needed to drive one mile on the combined EPA driving cycle and corresponds to driving level highway at about 57 mph in moderate weather. Knowing this number and my miles to destination tells me how I need to drive to make it. This number slowly ticks down as I drive (occasionally ticking up on a long downhill drive), it doesn't fluctuate wildly as I go up and down shallow slopes and small hills. Nominal miles yields a much more reliable idea of remaining charge than an estimated-miles number can.

Having this number enables useful discussions about range and energy use among owners. If someone is planning a trip over the pass from Bellevue to Ellensburg, I can say that I've done that several times: traveling the ~100 miles over the 3,000-foot pass at 60 mph in moderate weather used 113 ideal miles and closer to the 70 mph speed limit used 119. It also makes planning for elevation possible. Every 1,000 feet of climbing uses up about 7 miles of nominal range, and going downhill gives about half of that back. Knowing that simple approximation makes it possible for a driver to plan a trip over a mountain pass just by knowing the required distance and elevation change. If other automakers use the appropriate nominal mile energy unit, these conversations will work across different makes and models, allowing drivers to share approximate energy expectations without a lot of goofy conversion math.

That probably sounds complicated. Just remember, electric vehicles are intended for local driving within their single-charge range. Most of the time the answer to the "do I have enough charge" is "yes, of course you do." It's only for the rare long trip that figuring things out is needed. Having good state of charge information available all the time will allow new drivers to develop experience and insight from their easy local driving that will make it possible for them to figure out which longer trips are practical. It's critical to widespread electric vehicle adoption that automakers get it right.

Trading a gas pump for a plug is a wonderful thing. It's far more convenient, takes less of your time, and saves you from breathing toxic fumes and smelling like gas for hours after fueling. Charging is a different experience than pumping gas and understanding the subtleties takes time. I've been driving electric for over two years and I'm still learning. Potential EV owners might want to get a head start on the learning curve, and maybe save a bunch of money as a result.

Mostly, I'll relate how charging works for a Nissan Leaf, a four-door, five-passenger hatchback with a range of about 100 miles, but I'll also mention other plug-in vehicles. The Leaf is intended for typical daily driving, which for 78% of drivers in the US means 40 miles or less per day. Occasional longer trips are possible and understanding charging will help you evaluate whether an EV will suit your driving needs.

Level 1 Charging

Level 1 Charging - Standard House Outlet

Level 1 charging is the technical jargon for plugging your car into an ordinary household outlet. For a Leaf, this means about 4.5 miles of range per hour of charging, or about 22 hours for a full charge. Wow, does that sound terrible! But there's a problem with thinking this way: you'll rarely need to do a full charge from flat empty to full. If you drive 40 miles per day and charge overnight, you'll be back to full in 9 hours. When you're sleeping, it doesn't matter if it takes one hour or 9 hours to charge.

But what if you have to drive a lot one day, say 80 miles? Sure, it would take 18 hours to get a full charge, but with a 9-hour overnight charge, you'll be ready for your normal commute the next day. If you drive less than 40 miles per day or charge for more than 9 hours, you'll work back up to a full charge over the next few days.

If you need to drive 80 miles on consecutive days, you'll need an alternative. Maybe you'll drive your other car, that gas-burner you keep around for long trips, or if there's public EV charging in your area, you can charge away from home while you're parked to do your shopping or other errands.

Level 1 charging at work could also be a supplement for people driving over 40 miles per day, or even a substitute for those who can't charge at home (because they don't have a garage or fixed parking place, for example).

Since it's easy to get 40 miles of range charging overnight from 120V, Level 1 is perfectly suited for overnight charging of the Chevy Volt, a plug-in hybrid with a 40-mile all-electric range.

Although Level 1 charging is generally too slow for a road trip, it can be helpful as destination charging. Cathy and I drove 90 miles to San Juan Island, charged for a few days in a friend's garage when not cruising around the island, and left with a full charge. That was great, but I wouldn't want to have to wait for Level 1 charging in the middle of a travel segment.

Beyond range issues, Level 1 may not be suitable for primary charging in all cases. In extreme climates, more power may be required to maintain proper battery temperatures. In these cases, Level 2 charging may be more appropriate (see below).

DC Fast Charging

Blink DC Fast Charge Station photo by ECOtality

At the other end of the spectrum is DC Fast Charging, the fastest type of charging currently available. It provides up to 40 miles of range for every 10 minutes of charging. These stations are expensive (up to $100,000) and require more power than your house, so you'll never have one of these in your garage.

They are going to start appearing as public charging stations in the next year, beginning in the Leaf target areas. If there's one conveniently located near where you drive, you can get back up to 80% of a full charge while getting lunch or drinking a latte. Charging this fast makes it far more practical to drive beyond an EV's single-charge range in one day. It's still not going to make a one-day 800-mile drive practical, but a 200-mile drive with a couple of charging breaks can be quite doable.

Level 2 Charging

ChargePoint/Coulomb Level 2 Charging Station

Between the cheap Level 1 and expensive DC Fast Charging stations sits Level 2 charging. Level 2 supplies 240V, like what an electric dryer or oven uses. It goes through a box and a cord that improves safety by waiting to send power to the plug until it's plugged into an EV. Level 2 allows for a wide range of charging speeds, all the way up to 19.2 kilowatts (kW), or about 70 miles of range per hour of charging.

However, the charging stations being put in with federal grant money don't support the full range of Level 2 charging and max out at 6.6 kW or around 26 miles of range per hour of charging.

Both Level 1 and Level 2 charging stations simply deliver household electricity to the car. Electronics on board the car transform the wall power into the proper form to charge the battery. This bit of electronics built into the car also has a maximum power rating. The first model-year Leafs can only use 3.3 kW, about 12 miles of range per hour, or about 8 hours for a full charge from empty. The Chevy Volt's on-board charger is also limited to 3.3 kW, although its smaller battery pack gets full sooner.

Nissan recommends that you install a Level 2 charging station at home. That's a reasonable thing to do if you don't mind spending about $2,000, just consider it part of the cost of the car. Early buyers in the Leaf target markets may be able to get into The EV Project and get a free Level 2 charging station plus an allowance toward the install cost. Failing that, there's a 30% federal tax credit (up to $1,000) for installing EV charging, which can make it less expensive. Still, if you are planning to use your EV for a daily commute of 40 miles or less per day, you should at least consider using Level 1 charging at home. You can always add a Level 2 charging station later if you decide you need it.

There will soon be 20,000 public Level 2 charging stations (limited to 6.6 kW) installed mainly in the Leaf target areas. Even if you only have Level 1 charging in your garage, if you're in the early rollout areas, you should have access to convenient Level 2 charging available while your car is parked and you're doing something else. These charging stations will make it possible to drive 60 miles to a baseball game and pick up about 50 miles of range in 4 hours while you're having fun, thus easily driving over the single-charge range while always keeping a healthy reserve.

Charge Time and Battery Capacity

It's misleading that charging times are generally quoted as time for a full charge. While it does take about 22 hours (Level 1) or 8 hours (Level 2) to charge a Leaf from empty to full, you're not likely to do that often because  you will rarely arrive home with a fully depleted battery. It doesn't matter if you're driving a 40-mile Volt, a 100-mile Leaf or a 240-mile Tesla Roadster, if your commute is 40 miles, you'll only need about 9 hours (Level 1) or 3 hours (3.3 kW Level 2) to charge.

When we bought our Tesla Roadster, we got the high-power 16.8 kW Level 2 charging station, which can charge the car in 3.5 hours. After driving the car for a few months, I realized it's all but pointless to have such a big charging station in our garage. It's rare that I drive over 40 miles in a day. The 16.8 kW charging station can restore 40 miles in under 40 minutes. I want that charging speed when I'm making a long trip, not when I'm sleeping at home. In fact, I manually drop the power I pull from the charging station to about 7.5 kW because it's a little nicer to our electrical panel and the grid, and my typical overnight charge is still under 2 hours. Ignoring the fact that Tesla is still using the now-incompatible proprietary charging plug they picked before there was a chosen standard, most people buying a Tesla Roadster today would be well-served to buy a 6.6 kW charging station for home.

3 Roadsters Sharing the Charging Station at Burgerville

Level 2 Charging, Road Trips, and Charging Speed

Already, Ford has announced that the upcoming electric Ford Focus will support charging at 6.6 kW, and is making fun of the Leaf's 3.3 kW Level 2 charging limit. By the time Ford actually starts delivering the electric Focus, Nissan may have already upgraded the Leaf to 6.6 kW charging. I don't think it will be long before mainstream EVs are capable of even faster charging. The Tesla Roadster can charge at 16.8 kW, which combined with a larger battery pack makes 400-mile drives possible even without DC Fast Charging. Given that Level 2 charging costs 1/10 of what a DC Fast Charger does, I can imagine a lot of driving being supported by full Level 2 charging stations in areas that can't justify the investment in DC Fast Charging.

Personally, I'm disappointed we're spending so much money installing these 6.6 kW public charging stations rather than full-speed Level 2 chargers when most of the expense is usually just running the wires and buying the fancy box. A typical commercial Level 2 install runs around $10,000 for a charging station that's connected to a network and capable of billing the user. Cranking those charging stations up to the 19.2 kW limit would add a small incremental cost, perhaps 10%, and would allow for much faster charging. If you're a business owner installing a charging station and have to dig a trench and/or run conduit, even if it's just a for 6.6 kW unit, I strongly recommend planning for running 100A wire later without having to retrench or replace conduit so that upgrading to a 19.2 kW charging station will be much less expensive.

If you are interested in driving an electric vehicle, I'd like to tell you how to ensure that you'll have a great experience, or at least make sure you don't have a disappointing experience.

Here's the secret formula for EV success: make sure the range of the vehicle suits the driving you plan to do with it. I know that sounds pretty obvious and easy, but there are two big barriers to success: bad reporting in the media and obfuscation by the automakers. There's also a bit of complexity: just like gas mileage, you can't express EV range with a single number. I'll get that all straightened out from the perspective of someone who has been driving all electric for almost two years.

In addition to the general facts of driving electric, we recently got some more specific range numbers for the upcoming Nissan Leaf which I'd like to put into perspective for potential buyers.

Reporting the Obvious and Irrelevant

If you follow EV coverage in the press, you'll find a steady stream of articles from reporters who think they've discovered the flaw that will deflate all of the hype about EVs. Their basic premise is that EVs won't work because they take too long to charge and there's nowhere to charge them. These articles are either totally made up, or based on the bad experience of a single EV driver and don't represent the real experience of the majority of EV drivers who purchased a vehicle appropriate for their needs. My purpose here is to make sure you don't become the excuse for some lazy reporter to write yet another of these uninsightful articles.

Would a newspaper publish an article about a Ford Focus owner who was disappointed that he couldn't fit his wife and seven kids in the car? How about a Honda Civic owner who's mad her car isn't suited for towing an RV? A Hummer owner who's mad about how much it costs to drive a mile? Of course not, these would be laughably obvious mistakes made by the owner in choosing a car.

For the consumer properly informed on the benefits and limits of electric vehicles, it's equally obvious that buying an EV with a 75-mile range to do a daily 74-commute with no charging infrastructure isn't going to yield a happy driver. That's obvious and boring.

The real story is that there is no problem with range or lack of charging infrastructure if you can just charge at home to meet your driving needs, instead it's a real convenience not to have to fuel your car away from home. So let's see if you qualify...

The Rule

To be a happy EV owner today, you want to buy a car that has enough single-charge range to handle all of your daily driving with a reasonable buffer for typical errands without needing to charge anywhere other than your charger. (Your charger is probably installed at your home but might also be at your work location.)

The good news is that for most drivers, the required range is surprisingly low. A 2003 US Department of Transportation survey (PDF) found that 78% of Americans drive less than 40 miles a day. If you're in the 78%, and don't often have big exceptions to that daily commute distance, then an EV that gets at least 70 miles of range in your driving conditions will most likely make you one happy camper. (But keep reading to learn how to evaluate EV range.)

Starting this fall, we'll start to see a lot of chargers getting installed in a few metro areas in the US and other countries. As this happens, and EV ownership goes up, more and more charging will become available and convenient. As that happens, charging away from your home charger will become more dependable and the usable range of EVs will expand as a result. For example, if you can charge at home and at work, then the usable range of an EV is doubled because you only need to travel one way on a single charge (with a reasonable buffer).

Since there's going to be limited availability of affordable, practical, freeway-capable EVs in the near future (as in zero today, and a few thousand Nissan Leafs starting to trickle out starting in December of this year, then more from other automakers to follow), it's OK if the first few models of EVs don't work for you, they will work for millions of potential buyers. Wait for an EV that will be right for your driving needs.

The Win

After you've driven electric for a month, spending just a few seconds to plug in each night to start every day with a full charge, without ever having to stop at a gas station, you'll wonder how you ever tolerated the hassles of driving a gas burner.

In addition, the experience of driving electric is just better: you get instant acceleration without waiting for the engine to rev up and the transmission to shift, another nuisance of driving gas that you'll only notice when you get used to driving without it.

Bonus: no tailpipe emissions, low-to-zero emissions from electricity generation, and never having to worry about the price at the gas pump.

Evaluating EV Range

Just like gas mileage, EV range can't be expressed as a single number. Even the two EPA city and highway gas mileage numbers you see on vehicle stickers don't tell the whole story. This is such a big issue with gas cars, the caveat "your mileage may vary" has become part of our cultural vernacular.

Let's start by going over how gas mileage works. Those gas mileage numbers on the sticker in the window are determined by driving the car on two standard EPA driving profiles meant to simulate typical driving conditions, which have been recently revised to better represent actual driving conditions by including things like using air conditioning on part of the cycle.

Gas mileage depends on a number of factors, including passenger and cargo weight, HVAC use, start/stop frequency, road incline, rain/snow, and so forth, but the biggest factor is speed. At low speeds, gas mileage suffers because there's an overhead of running/idling an engine that burns fuel whether you're moving or not. Stop and go traffic is also bad news, because you invest energy in speeding up only to throw all it all away by converting your car's momentum into heat plus wear and tear on your brake pads. At higher speeds gas mileage suffers because wind resistance goes up rapidly with speed, so much so that it takes more energy per mile in a way that starts increasing dramatically at the low end of freeway speeds. Somewhere in the middle, at a moderate, steady speed, is where you get your maximum gas mileage.

Electric vehicles behave similarly, except they get punished less in stop and go traffic because, like hybrids, they can slow down with regenerative braking wherein the motor is driven by the drivetrain to act as a generator to put charge back into the batteries. This not only improves energy efficiency, but also reduces brake wear.

Given this complexity, how can an automaker tell you how your gas or electric car will perform under your driving conditions? Answer: they can't.

While you can argue that it's even more important to understand energy efficiency (in the form of single-charge range) for an electric vehicle, there's the ugly truth about burning gas that no one likes to talk about: it's no good for predicting long-term fuel costs. With a proliferation of gas stations everywhere, range isn't something you think about for a gas car. What you do think about is your pocketbook. Better mileage means cheaper stops at the gas station. While knowing your gas mileage might tell you what you'll be spending at the pump this month, it doesn't say anything about what you'll be paying next month or next year. Anything from a hurricane, to Wall Street speculators, to a political action by OPEC, to the whim of some oil nation tyrant can cause gas prices to double by barely nudging the precarious balance between world oil supply and demand. Electricity rates are far more stable, especially when it comes from renewable sources that aren't subject to the unpredictable economic forces that rule the world's fossil fuel energy market.

How can a potential buyer figure out if a given EV has the range required to convert from the hassles of driving gas to the joy of driving electric? Read on...

Case Study: the Range of a Tesla Roadster

For most people, buying a $109,000 two-seat sports car is totally out of the question, whether it's a gas-burning Ferrari or an all-electric Tesla Roadster. Being able to go from 0 to 60 mph in under four seconds isn't going to get the kids to school or bring home the groceries from Costco. But, as of this writing, Tesla Motors is the only automaker selling a production, freeway capable electric vehicle in the US. If you dig a little, their web site provides a wealth of information about driving electric that will be of help to any potential EV driver.

The best illustration I have found of the effect of speed on efficiency, and thus range, is this graph from Tesla Motors showing how the Roadster's range varies with speed, while holding other factors constant at favorable values (constant speed, no AC, no driving up a mountain, etc.).



The EPA range number for the Roadster is 244 miles. From the graph, you can see that you get that range driving at about 55 mph. If you have to pick one number to describe range for a Roadster encompassing city and highway driving, this is a pretty good choice, and it's a real number that I've personally verified as much as possible without actually driving the car until it stops. Likewise, the value of about 180 miles for 70 mph matches my real-world experience. Simon Hackett and co-driver Emilis Prelgauskas came close to the graph's 34 mph range number by driving 313 miles on a single charge in Australia last year. Perhaps someone will be patient enough to try out the 17 mph peak on the graph at over 400 miles of range, but that would be a very long drive!

I'd say Tesla did a good job here, picking a reasonable single number for stating range based on some combination of the EPA city and highway cycles. They also provide the graph showing the whole story, at least with respect to speed, although to find it you have to dig down into their blog entries to find the article with the graph and full explanation.

But there's a bit more to the story that requires more digging. The above range numbers are for using the entire battery charge from full to empty, something you really don't want to do on a regular basis because it's not good for the life of the battery pack. For normal daily driving, you don't need 244 miles of range, so Tesla provides a "standard" mode of charging that only uses the middle 80% of the battery pack. This will extend the life of the battery pack and still give you 200 miles of range at 55 mph, or about 160 miles at 70 mph. This is between four and five times what most of the drivers in the US need for their daily commute. For daily driving, the range of the Roadster is ridiculously high. Going on a road trip beyond the single charge range is doable, but it requires patience and planning. This situation will get a lot better as high-speed charging stations start to appear later this year.

The numbers also get worse in really hot weather. Last summer I drove from Portland to Seattle in 100-degree weather, about 180 miles. This trip is easy at 55, in fact even at 65 mph it's no problem. But this trip, with the HVAC system using energy to keep the battery pack cool, it took getting off the freeway and careful route planning to reduce both distance and speed to get home without having to stop for a partial charge.

The upshot: if you live in an extreme climate, with either a lot of sub-zero winter days or 100+ degree summer days, you'll want to add more buffer to your required EV range.

The last big issue is aging of the battery pack: as the battery pack ages, its capacity will decrease gradually over time, then drop more rapidly as the battery pack wears out. Our car is performing the same as it did when we got it one year and 9,000 miles ago. Other Roadster owners have crossed the 20,000 mile mark, and so far I haven't heard of anyone noticing a loss of range. Tesla's battery pack warranty is only 3 years or 36,000 miles, which is in line with other high performance sports cars, but is a bit underwhelming compared to their statements of expected battery life, seven years or 100,000 miles. Nissan says their battery pack should last 10 years, and because the Leaf is a much more mainstream vehicle I expect they will offer a much better battery warranty.

Still, if you're planning to drive your new EV for 5 to 10 years, it's not going to be smart to buy an electric car that's right on the edge of meeting your needs with its full factory-fresh range.

Our Electric Garage

In July of 2008, while we were waiting for Tesla to build the Roadster we reserved in 2006, we were fortunate enough to buy a rare 2002 Toyota RAV4-EV from its original owner in Berkeley, CA. If you've seen Who Killed the Electric Car, then you've know what a great electric driving experience the lucky few drivers had during the brief period where California required all of the automakers to find a way to reduce tailpipe emissions to zero.

When we got the RAV4-EV, we expected it would take care of about half of our driving. We were wrong by a wide margin: it took over 95% of our driving. The only time we burned gas was when we each had to be different places at the same time. Despite our EV enthusiasm, we were range anxiety victims and overestimated how much range our driving really required.

In our experience, the RAV4-EV gets about 100 miles per charge. Even staying out of the top 10% and bottom 20% of the battery pack means we can drive 70 miles per charge under our typical driving conditions, and can handle any driving conditions with enough range we don't generally have to think about it.

When our Roadster finally arrived nearly a year later, we were totally converted to the electric driving experience. Having a second electric car meant we didn't have to choose which of us got to drive the smooth, quiet car.

Our hope is that the Leaf will bring this sort of EV capability into the mainstream in an affordable, practical, safe vehicle.

Nissan Leaf Range Numbers

The first range number we heard for the Nissan Leaf was 100 miles using the EPA's LA4 drive cycle. Darryl Siry gets credit for being the first to point out that the LA4 drive cycle is a poor choice for describing EV range as it's a city driving cycle that's nicer to the range than the combined city/highway drive cycle that is used by Tesla. Siry also wrote a great piece on the issues with range numbers and the need for federal regulations on how they are reported which added perspective to my personal experience and helped inform my writing here.

On June 19th 2010, we got some more range numbers from Nissan via Forbes. To summarize:

• Cruising at 38 mph in 68-degree weather: 138 miles.
• Suburban traffic averaging 24 mph, 77 degrees: 105 miles.
• Urban highway, 55 mph, 95-degrees, A/C on: 70 miles.
• Winter city driving, 14 degrees, averaging 15 mph: 62 miles.
• Stop and go urban traffic averaging 6 mph, 86 degrees, A/C on: 47 miles.

The Forbes article is typical anti-EV fear mongering, the facts presented with pithy commentary but no critical analysis. Have you ever read an article on how your gas mileage drops in stop-and-go urban traffic during the heat of summer or the cold of winter and how much that's going to cost you when you're driving your gas-guzzling SUV? Of course not. But you do hear about how it will affect the range of an EV that isn't even on the roads yet. It's great to get more facts, but try to ignore the hand-wringing hysteria that makes it sound like the federal government is about to repossess all of the gas burners and force everyone to drive a Nissan Leaf.

The fact is, the Leaf doesn't have to meet the needs of every driver in the US. It just has to meet the needs of the few thousand people lucky enough to be able to buy one in the next year. Even that worst-case 47 miles is going to be good enough for millions of drivers now (remember that 78% of US drivers commute less than 40 miles per day) and good enough for even more drivers when there are convenient chargers at workplaces and malls.

Is the Leaf's Range Right for You?

I think the best way to figure out what range an EV needs to have to suit your needs is to monitor your driving. Just write down your odometer when you get home each night. From that, you can figure out how far you actually drive. Be sure to get not only your regular daily commute, but also some examples of exceptional days with extra appointments, shopping, detours, etc. If you have an additional vehicle that would supplement your EV, throw out any long drives that you would choose (in advance) to handle with that vehicle. Then add a buffer for the unexpected, and, if it applies, more buffer for the extreme driving conditions that reduce range.

People who haven't driven an EV will be tempted to always have half of the battery in reserve for surprises, but most experienced EV drivers are very comfortable driving down to 30% or even 20%. (With the Roadster where I get great feedback on the state of charge and know it won't hurt the battery, I have no problem driving down to 10%. With the RAV4-EV, which gives less precise info, we try to stay out of the bottom 20%.)

If you commute 70 or more miles per day in a city that regularly has horrible traffic, freezing cold or sweltering hot days, and isn't planning for charging infrastructure, then don't buy a Leaf to be your only car this year. Wait until the cars and the charging better suit your driving needs. There are more than enough of us to buy up every single Leaf Nissan can make in the next 12 months, so don't become fodder for another annoying article about how EVs are impractical because someone bought one that's not suited to their driving.

If the Leaf's range numbers do suit your driving needs and you want to get an early start driving electric, then sign up, right now. They are going to sell fast. But before you fully commit to a purchase, get the information you need to determine if the Leaf will meet your needs, and get that info directly from Nissan. Don't depend on a conversation with your local auto sales drone.

I'm glad we have learned more about the Leaf's range months before anyone will be committed to buying one. Next up I want to see a graph like Tesla gives for the Roadster range vs. speed under optimal driving conditions. I also want to know if the range numbers given are for using the full battery to its maximum range, or if they include allowance for the reserves at the top and bottom of the charge cycle needed to maximize battery life.

If the Leaf will meet your needs, you won't regret switching away from gas. The benefits of charging convenience and drivability are great motivators to be among the early adopters to buy one of the first mainstream factory electric vehicles.

DEFCON is an annual computer security conference, the inexpensive and unruly counterpart to the more expensive corporate Black Hat security conference. From computer security briefings to the toxic barbeque to lock picking contests to a 52-hour competition to turn the electric conference badge into something more by any available means, DEFCON has something for everyone.

My focus is generally attending the briefings on computer security, privacy and civil rights issues, but even that consists of five parallel tracks of concurrent talks, so I only get to see a fraction of what's being presented.

That said, here's my summary of what I learned this year.

Picking the Lock on Your Browser

I trust everyone knows that when you're entering sensitive personal information, like bank account and credit card numbers, into a web page you need to look for the little lock icon so that you know you aren't revealing your info to some malicious criminal. Technically speaking, the lock (along with the https:// in the address bar) guarantees that you are sending that info to the web site you intend (not some malicious forgery) and that the info is being sent in an encrypted form so that even if a criminal is recording all of the data as it is transmitted across the Internet, your private information can't be read.

For the lock to be effective, you need to make sure you entered the correct address into your browser. Getting you to enter an incorrect address is the basis of what is called "phishing." One example of phishing is sending fake email messages that look like they came from your bank, or eBay, or Amazon, etc., which encourage you to follow a link in that email. The link might look like a link to the proper institution, but the actual address is to another site. For example, you might be sent to http://ebay.criminalscammer.com/ which has no association with ebay.com and will instead steal your eBay credentials if you type them into their bogus site. The fake link can be very insidious where it uses some wacky foreign alphabet character that makes the link look like the right web site, something like bankøfamerica.com. You might notice the slash through the "o", but there are other character substitutions where there is no visible difference.

This brings us to the first two rules of Internet safety:

Rule 1: Don't trust a link that you get in email, no matter who it says it's from. Especially don't trust it if it takes you to a bank or commerce web site. Even links to non-commerce sites can be malicious, since there are flaws in browsers that allow a malicious web site to take over your computer, but that's a whole different topic. So, if your best friend in the whole world emails you a link to the funniest photo ever, and you just have to see it, be skeptical and consider verifying the source of the link before clicking it.

Rule 2: Whenever you are about to type anything into a web page that you wouldn't want posted on the bulletin board at the local prison, make sure the link starts with "https://" and that your browser is showing you the lock icon.

That's where we were until early 2008. As long as you always typed in your web addresses, or used bookmarks you created from web addresses you typed in, and you looked for the https:// and the little lock, you were safe.

Then last year, Dan Kaminsky found a problem, but first I have to explain another vulnerability.

There's a step in the web communication process that can be subverted. When you type https://www.yourbank.com/ into your address bar, your browser has to do something like looking up a phone number. Computers on the Internet aren't addressed by name, but instead by a number called an IP address. It's like when you place a phone call, you don't type in someone's name, you enter their phone number. There are special servers on the Internet, called DNS servers, that perform that lookup. So, when you type https://www.yourbank.com/ into the address bar, your computer connects to a DNS server and asks for the correct IP address. That process can be subverted. It's been known for a long time that it's easy to do this locally. So, if you're using the WiFi connection at your local coffee shop, some criminal might also be sipping coffee there and sending your computer fake DNS responses that will send you to their evil server instead of your bank's server.

Rule 3: Don't trust web pages when you're surfing from a public access point. This includes free WiFi at coffee shops and libraries, and also wired Internet connections at hotels, Internet cafes, etc.

That used to be a good rule, until Dan Kaminsky pointed out a problem in the DNS system that has been there for years. There was a flaw in the programming used by DNS servers that made it possible for the bad guys to attack the server and trick it into sending our false information. So, even if you typed in https://www.yourbank.com/, the real DNS server might send you a bogus response that would send your browser to a criminal web server. This is a very bad problem as nearly all of the millions of DNS servers out there were vulnerable. Dan worked closely with the folks who control the majority of the DNS servers to get the flaw fixed on as many servers as possible before announcing the problem to the world.

The careful reader might be thinking that even if someone fakes your DNS responses and sends you to the wrong site when you're trying to do your banking, the https:// and the little lock means that you are connected to the real bank site and your information is encrypted so it can't be read even if it's intercepted. That was true until...

Getting Valid Certificates for Fake Sites

This year at DEFCON, Dan Kaminsky announced another flaw in a major system behind the safe operation of the Internet: it's possible for the bad guys to trick browsers into thinking they have valid certificates for sites they don't own. Certificates are the mathemagical basis of how your browser's little lock icon determines that it's safe to enter and send your private information securely to the party you intend and no one else. The certificate does two things: it proves to your browser that the site it's talking to is the real site for the address in your address bar (which is why it's critical that you have the correct address in your address bar) and it gives your browser the means to establish a secure communication channel to that server which can't be read by anyone else even if they intercept all of your transmitted data. It is widely believed that this security cannot be broken even with a lifetime of effort by an army of supercomputers. And that's still the case, except: the bad guys can get real certificates that allow them to impersonate secure sites.

The trick is somewhat technical, but it is fixable. Hopefully, this flaw will be taken as seriously as the DNS issue was and the several contributing flaws will all get fixed soon. If you're not interested in the technical details of the flaw, you can skip the next paragraph.

When you apply for a certificate from one of the many certificate authorities, you submit a document that states what domain name you want secured. There are multiple formats for encoding this string, including preceding length byte and zero-byte terminated. If you combine both, evil ensues. For example, you can submit a form using the length-byte format for the domain [37]www.yourbank.com[0].criminalscammer.com where [37] represents the length byte covering the entire string and [0] represents a zero byte in the middle of the string. Some certificate authorities will parse this string, pay attention of the length byte, but recognize that the zero-byte isn't a valid character (the digit '0' is not represented by a zero-value byte in order to avoid confusion when using zero-byte terminated strings, see info on ASCII encoding) and parse the string as www.yourbank.com\x00.criminalscammer.com. Their computer decides this is a perfectly reasonable request and contacts the owner of the criminalscammer.com domain to make sure the request came from them. The criminal scammer validates the request and the certificate is granted. The problem comes when a browser gets a bogus DNS reply for www.yourbank.com which directs it to contact the evil server with the wacky certificate. When the browser encounters the zero-byte, it may interpret the wacky domain name differently than the certificate authority and treat that zero-byte as the end of the string and decide the certificate is for www.yourbank.com.

Once this is set up, the victim submits banking info to the evil server and now the bad guys can log into the user's bank account. That's a bad thing.

The good news is that for this to be a problem two things have to occur. First, the user has to get directed to a fake site through a bogus DNS reply, and second the browser has to have the flaw that allows it to see the phony certificate as valid for the legitimate site. Which brings us to:

Rule 4: There is no rule four, follow rules 1 through 3 to avoid getting sent to a counterfeit web site.

We hope that certificate authorities will stop granting these zero-byte certificate requests and browser vendors will fix their code that interprets these fraudulent certificates.

Colleges Throw Out Students' Internet Privacy, Expose to Fraud

Endgrain, an observant student at the University of Southern Maine noticed something odd when he entered a chat room after logging into the university's network: people in the chat room started addressing him by his full name. He did some sleuthing and found out how his university was broadcasting his full name to everyone on the Internet.

When a student at USM logs into the network for the first time, they have to enter their username and password. The network then remembers that machine (by its MAC address) and thereafter lets the user onto the network without entering credentials. It also assigns that student an fully Internet accessible IP address, and maps that IP address to a domain name that includes the student's first and last name. There are a number of problems with this scheme.

First, because the IP address is publically available on the Internet, with no intervening router or firewall, the student computers are open to direct outside attack from anywhere on the Internet.

Second, because the IP address has a full DNS name revealing the student's name, the student is fully exposed to all sorts of privacy attacks. Every web site they visit logs those visits, and hence logs the student's name. Likewise, Google searches are logged and thus a student's search history is exposed to the world. Many other Internet activities expose students to a loss of privacy.

USM isn't the only school doing this to students, at least the practice of assigning DNS names that include each student's full name. According to research done by Endgrain and Dan Kaminsky, some 60 universities are doing this.

Presumably, this destruction of student privacy is done to streamline RIAA lawsuits against students pirating music. With the DNS clearly revealing a student's name, university, and even approximate location on campus, the RIAA can serve up lawsuits without having to go through the bother of getting a court order to find out who is behind an IP address identified as illegally sharing music.

The worst part of this whole thing, at least as USM has implemented it, is that it actually hurts the ability of the RIAA to identify who's behind an IP address. Anyone on the university network can watch traffic and determine which MAC addresses belong to which students. It's then trivial for a malicious student to spoof another student's MAC address then do bad things masked by the DNS name pointing to an innocent student all without ever learning that student's network password. Because of this flaw in how USM allows unsecured logins by MAC address, any student who gets sued by the RIAA has an easy defense: it's wasn't me, someone must have spoofed my MAC address. Guilty students get an easy defense, and innocent students are left to defend themselves in court because of a flawed system.

Everyone loses here. Students lose their anonymity on the Internet and can be identified by anyone, with no need for having a good reason to identify a user or obtain a warrant or court order. The RIAA, and other intellectual property owners, can't actually use the DNS names to identify students since the system is so easy to subvert. Universities look like spineless dorks for outing their students and exposing them to computer attacks.

Students who go to universities that are doing this to their student body should be raising the alarm and forcing a change in policy. We don't want our universities to be teaching students that they have to abandon their first amendment rights for the illusion of corporate convenience.

Tesla Motors Announces Some News

On Wednesday, Tesla Motors Chairman Elon Musk announced some changes at the company. In a nutshell, they are going to:

• Work to be cash-flow positive within six to nine months.
• Ramp up the delivery rate for pre-sold Roadsters.
• Build revenue from powertrain sales to other car companies.
• Musk will replace Ze'ev Drori as CEO.
• Drori will remain as vice-chairman of the board.
  
• Scale back Model S work until their assembly site passes the environmental review.
• Delay the production target for the Model S by six months.
• Finance Model S production primarily with a low-interest DOE loan.
  
• Implement a modest reduction in near-term headcount.
• Survive the economic turmoil on Musk's dime for as long as it takes.
  

The media and blogosphere as been laser-focused on writing copycat stories on how the current economic problems have led Tesla to layoffs and the Model S delay. That generates eye-catching headlines, but it misses the real story.

Building a New Car Company

In February of 2007, Tesla announced their assembly plant would be in New Mexico. After over a year of silence on that, they announced a new plan in September: assembly plant in California. Clearly things aren't going as smoothly as Tesla had hoped.

Of course the Model S got delayed. They were running on a very tight schedule to deliver the Model S in late 2010. To get to that point, there's an incredible amount of work for them to do. Apparently they have made good progress designing the sedan, both inside and outside, but that's just the beginning. They also have to design and build a production facility and the assembly line tools and process, and create supplier relationships that will be 100% reliable. There's a lot of that work that depends on knowing when and where they are going to build their assembly facility. If and until they get the environmental approval for the San Jose site, they don't know either.

Also tied to the environmental approval is the DOE loan. If they wait for the loan to provide the majority of funding needed to develop the Model S, the Tesla investors can avoid giving up equity in another round of financing, e.g. an IPO. Right now, raising money from investors is more expensive, which further increases the appeal of the DOE loan. So of course they need to delay spending money unnecessarily until they can get the DOE funds.

Thus, cost cutting and modest layoffs. Now that they expect to have their headquarters located at their production facility, they want to consolidate operations. Combine that with Roadster design work being finished in Hethel, and some general belt-tightening and you have some layoffs. That's bad news for the Tesla people who will lose their jobs. I've met a number of Tesla employees and I've been universally impressed. They are a bright, enthusiastic bunch doing amazing and important work. I hate to think of people of that caliber losing their jobs. I hope they are able to quickly apply their talents to new jobs. It's bad news for those people, but it's not bad news for Tesla. It's just a matter of Tesla staying lean until they know when and where their Model S production facility will be built and can get working 100% on that huge effort.

The Real Risk

Here's the scariest part of Musk's announcement:

If all goes reasonably well, we will receive [the environmental] approval in Q2 next year.

Have you ever heard of an environmental approval going smoothly? If something kills Tesla Motors, it's not going to be the Wall Street fiasco, it's going to be some wet patch of dirt or an endangered species we've probably never even heard of. It's ironic that a company trying to develop technology to help save the global environment from man-made disaster is at risk of failure because of one of the literally millions of species that are threatened by the problem that Tesla would like to help solve.

But the media is having lots of fun writing about the subprime loan mess, reckless unregulated banking, and the resulting panicked federal intervention spending spree, so that's what they are writing about.

The Good News: Profits

There's even another thread to this story that has been completely missed:

Our powertrain business is profitable today and is also growing rapidly.

What is that all about? We've heard rumors that Tesla is working on an electric powertrain for another auto maker, but nothing has been confirmed. Now Musk tells us that not only are they doing it, but that it's already profitable. That's real news! That could be the single most important thing that Tesla has announced all year. It could be the beginning of a business model that puts Tesla's technology into vehicles in quantities that will show the world that the Roadster was just a successful gesture to get people thinking about electric vehicle technology.

It could well be the direct path to achieve Tesla's goal to reduce our global dependence on burning petroleum which is damaging our global climate, funding horrible governments around the world, and betting the entire free world economy on the whims of those undemocratic governments.

But how is the media going to work that into a story about today's immediate financial crisis? Especially if we have to ask questions and do research instead of just writing the same story everyone else is writing; that's just too hard.