Tesla may have decided to redouble its battery station efforts for economic reasons, too. As pointed out by Bloomberg, California stripped Tesla of some of its zero-emission vehicle (ZEV) credits earlier this year after revising its rapid refueling rules. The new standard requires that cars be fueled to a 285 mile range in 15 minutes, meaning the Model S -- which can receive a 160-mile supercharge in about 30 minutes -- no longer qualifies. Meanwhile, hydrogen-fueled cars continue to receive the maximum ZEV credits, since they can easily be refueled in that time. Prior to the decision, Tesla had been selling the excess ZEV credits to other automakers, which is one of the reasons it turned a profit for the first time last year.

Once the EV maker opens the battery stations it will re-qualify for the credits, but there's one caveat: Tesla must prove the system is sufficiently used. Which begs the question: how popular will the stations be? That remains to be seen, as users will need to pay $60-80 for a battery swap and are required to either retrieve their old packs on the return trip or pay a hefty upgrade fee. That means customers used to "free," or who can't deal with the logistics may just stick with superchargers. (Though we imagine folks with the resources to own a $71,000 Model S won't worry too much about it.)

However, Tesla has been turning a profit lately with or without the ZEV credits. And politics and logistics aside, by the end of the year Model S owners in the San Francisco to Los Angeles corridor should have another re-fueling option. For a reminder about how it works, check the video from last year's demo below.