Tesla Model S

As Tesla Motors showed last month, it takes as little as 90 seconds to swap out a battery on a Model S electric vehicle. Unfortunately for the California-based automaker, it could take as little as 90 days for the state to shelve a law that made such battery-swapping capabilities a profitable exercise for Tesla. The California Air Resources Board (CARB), which is heading the efforts to provide incentives for automakers to make zero-emissions vehicles for the most populous US state, may rejigger its rules to disallow automakers from getting zero-emissions vehicle (ZEV) for offering battery-swapping, Green Car Reports says.

Battery-swapping qualifies for the ZEV credits because it allows a type of rapid "refueling" of an electric vehicle, similar to filling up a tank with H2 for a hydrogen fuel-cell vehicle. Forward-thinking automakers can sell these credits to automakers who need them, generating revenue. Such sales helped Tesla achieve its first profitable quarter during the Q1 of 2013. CARB will publish its proposed rule changes in early September, after which there will be a 45-day comment period before anything's decided.

Tesla, which first said the Model S was designed to allow battery-swapping in 2009, demonstrated them last month at the Tesla Design Studio in Southern California (we've provided the video again below). The automaker planned to build battery-swapping stations near its especially busy Supercharger fast-charging station locations and is not saying whether CARB's potential rule change will cause the company to ditch its battery-swapping plans. There are more details over on Green Car Reports.