Electric vehicles take too long to recharge. To charge a Tesla Model S just halfway takes five hours at a typical home or public charging station. But in its effort to make electric vehicles more practical, Tesla Motors is quickly reducing the charging times. Last September, it unveiled a network of “supercharging” stations—designed exclusively for its Model S and future electric vehicles—that could charge a battery halfway in 30 minutes. In May, it announced an upgrade that cut that time to 20 minutes. Now Tesla’s chief technology officer, JB Straubel, says the company eventually could cut the time it takes to fully charge the battery to just five minutes—or not much longer than it takes to fill a gas tank.