"The Roadster had an old generation battery," Musk told Auto Express." We'll upgrade it to a new generation battery pack and it should have a range of about 400 miles, which will allow you to drive from LA to San Francisco non-stop." The Roadster originally came with a 245-mile range, which is good for Los Angeles to Madera, CA. Tesla sold the Roadster, its first car, in the US from 2008 to 2011 and elsewhere until 2012.
It's not that the old Roadster batteries were failing regularly – quite the opposite, in fact – but li-ion EV technology advances rapidly, and so now we're extra curious what's in the new pack and how it will work. Will it be compatible with Tesla's Supercharger technology? How much will it cost, both for Roadster owners as well as for Tesla?
We've asked Tesla for answers to these questions, but all a spokeswoman would say is, "We have no further details at this time." At the shareholder meeting in early June, Musk said the "exciting upgrade" would happen this year, so if he was talking about the battery upgrade at that time, we should be getting more information on the new packs right soon.