While Elon Musk was entertaining a crowd of avid Tesla supporters at the company’s store in Paris, he asked what improvements to the Model S they would like to see. Several guests said they would like the car to have more range. “How much range do you want?”, Musk asked.
The answers he got were mainly within the 800 to 850 kilometer ball park, which translates to about 500 miles. Elon appeared taken aback. He explained that a battery with that much range would be extremely heavy, expensive, and impractical for normal driving due to its weight.
The most challenging aspect of selecting a battery that meets the needs of everyday consumers is finding the perfect balance between range, weight, and cost. Musk told his audience that modest improvements in battery range will take place over the next year, and result in batteries that deliver 500 kilometers of range or 300 miles. Musk has stated in the past that battery capacity would increase by approximately 5% a year for the foreseeable future, if not slightly more as Tesla’s Gigafactory begins driving down cost of battery production via economies of scale.
What followed was an idea that Elon tossed out, something he hasn’t mentioned before, although others have. “What if you had a trailer with a booster battery that you could use for long distance driving?” he asked. Then he told the audience that he was running on about 1 hour of sleep in the past 48 hours and might not be thinking clearly. But the notion of a tag-along trailer with an auxiliary battery makes a lot of sense for those times when people are driving long distances and really do need more range.
Tesla’s battery swapping station at Harris Ranch, CA has been the site for its pilot battery swap program, but that would be a lot more complex than hooking up a trailer and then dropping it off when it was no longer needed. Some sort of rental program would be easy to create.
You can see the entire Q&A session with Elon Musk beginning at the 11 minute mark.