In my mind a sports car can be driven on the open American road. Not coddled. DRIVEN. Hard. And not have to refuel every dozen minutes or so. According to the U.S. Census Bureau, there were 114,533 gas stations in the U.S. at the end of 2012, the last year for which data is available. There is currently one (ONE) Tesla battery swap station (Harris Ranch, CA). Elon stated at a shareholder meeting (June 2015) that more are NOT coming. The problem with any battery car, with today's batteries, is battery mass. Mass matters. Batteries need more, much more, power per KG of battery mass. Significant electrical distribution system changes also need to be made to allow for faster charging times.
Here's a battery powered car range and recharge time challenge: Using today's infrastructure (not tomorrow's), drive from Phoenix, AZ to Sunrise Park Ski Resort (215 miles and 8,000 foot elevation gain), ski six hours, and drive home - and do it in 13 or fewer hours.
Check out Tesla's web site for SuperCharger stations on this route and you'll find none. That, my friends, is why electrics are (generally) city cars, not cars for people who actually need to drive for hours on end. They may be quick, but they are not sustainably fast. Quick is not the same as fast. Acceleration does not equal velocity. Power does not equal energy. Keep total driving mileage to a low daily amount and recharge while you sleep, and electrics work great. Hit Route 66 or the open American road and it's game over. By the way, I do the Phoenix to Sunrise day trip all the time in my ICE car.
Some facts of physics, chemistry, electricity and mechanics (of course, none of this will be news to the Tesla engineering staff, or Elon):
- One gallon of gasoline contains about 33 kilowatt hours (KWH) of energy. At a weight of less than 7 pounds.
- A typical gasoline engine is about 25% efficient, thus getting about 8 KWH usable energy per gallon. The typical 15 gallon tank therefore contains about 120 KWH usable energy in about 105 pounds. If that tank is totally empty it takes about 6 minutes to refill and get another 120 KWH of usable energy.
- Considering batteries, a Tesla's 90% efficient 85 KWH battery (75 net KWH) contains about the same usable energy as 9 gallons of gasoline (63 pounds), at a weight of approximately 525 KG (1,155 pounds). Thus, a Tesla's 85 KWH battery weighs EIGHTEEN TIMES as much as the same amount of usable energy in chemical liquid energy form (gasoline). Of course, part of that mass issue is offset by the Tesla's lower mass for the total power delivery system including transmission, cooling system, etc.
- If the Tesla's 85 KWH battery is fully discharged, to recharge it in one hour, using a 240 volt single-phase charger, would take 85,000 / 240 = 354 amperes of current for one full hour. A 354 ampere, 240 volt, cable would literally be the size of a woman's forearm. 60% of the homes in the United States do not have electric service powerful enough. In other words, most homes in the USA cannot charge a fully-discharged Tesla in one hour. To get the charging time for that battery down to six minutes the voltage would need to be 2,400 volts and still require a 354 ampere rated cable.
- Even if it could be done, recharging a Tesla's battery in one hour would take at least TEN TIMES as long to recharge as a gasoline refill, and after all that the Tesla would still be left with only 75 / 120 = 63% of the total usable energy compared to the 15 gallon gasoline refill.
- In order to double the range of a car with a 15 gallon gasoline tank, you could add another 15 gallons capacity to the fuel tank and increase total weight by about 125 pounds (fuel plus additional tank materials). To double a Tesla's range, you'd have to install another 1,155 pound battery.
- One horsepower equals 746 watts. This is a scientific definition, not open to discussion. Thus, an 85 KWH battery can deliver a maximum 85 KW for one hour (H) or approximately 113 horsepower for one hour. That's about the same horsepower as a Toyota Corolla. In order to get the ridiculously high power ratings quoted for some battery cars, they literally use up the power of the battery in minutes, thereby forcing an hour (or hours) long recharge for only minutes of high power drive time. In other words, that Tesla can deliver its 500+ horsepower for just 1/5 of an hour (12 minutes) then it needs fully recharged which can take one hour, even with a SuperCharger. Drive full power for 12 minutes for every 60 minute recharge.
Mass and refuel cycles matter. Period. No one has rewritten the rules of physics, electricity or chemistry. Today's EV's simply weigh too much and take too long to recharge - if the electrical infrastructure even existed to quickly recharge them. We've gotten very good at controlling dozens (hundreds) of gasoline explosions per second, and turning that into meaningful transportation options on a global basis. The ICE powered car has set a high bar to overcome. The bottom line is that battery energy density needs to increase by at least five to ten fold, and massive electrical system upgrades need to occur, to truly compete with gasoline engines, for anything other than relatively short, daily, trips. Some day we'll probably all drive electrics, at least in the city where we can slowly recharge at night. But for now, there are serious limitations, especially for road trips.
I have been following Sion and other battery/energy storage developments with high interest. Clearly the ICE will face increasing competition. If batteries can get to much higher power densities, at lower cost, then over time the electrical infrastructure can be beefed up enough to get recharge times down to something like 10 minutes for a fully discharged battery to be recharged. The inherent advantages of electric motors versus ICE will organically push more and more people to consider electrics. It is coming, albeit at a slower pace than most realize. Electrical distribution system upgrades will take considerable time and costly effort, concurrent with addressing safety concerns related to higher voltages at the refill "stations".
The point of this post is to show that right now we have a ways to go to get to a point where batteries are energy-dense enough, and electric charging stations are ubiquitous enough, to alleviate the range and recharge time problem of electrics. It's sort a chicken-egg problem.
Tesla seems to be best positioned to make this happen. Let's hope Tesla is successful.