BMW, Daimler and Volkswagen joined forces in a joint presentation at the California Air Resources Board ZEV Technology Symposium to call for a global standardisation of the e-mobility charging infrastructure
The trio of German car companies wants to see one worldwide standard for smart charge communication as well as a proposed pathway for harmonising the two main standards for AC chargers and infrastructure.
In their existing form, there are two primary and parallel standardisation efforts for vehicle to grid communications – these are a joint ISO/IEC working group and an EPRI/SAE effort. These could result in two sets of standards, which Werner Preuschoff from Daimler described as "a lot of effort".
He and his colleagues instead believe that there should be one common set of standards based on the ISO OSI seven-layer reference model for interoperability. The basis needs would be optimised charging; automatic payment and billing; and value added services such as mobile access.
Preuschoff warned that failing to establish worldwide standards might keep electric mobility from becoming mainstream; as if different technologies need to be installed on vehicles to support regional standards, costs increase for similar goals while adding no value for the customers or the grid.
Ralf Oestreicher, also from Daimler, called for harmonisation between the two primary AC charger standards. He believes there are five primary customer requirements: high density infrastructure; high power; high convenience; high reliability and safety; and long-term viability. His suggestion is that using on-board vehicle AC chargers capable of up to 43kW for high power and high density is the best option while DC charging is only for a range extension use-case. A three phase power for charging beyond 7-10kW would reduce cost, volume and the weight of the charger and cable.
In addition, Oestreicher suggested that if all new single phase chargers were designed to be compatible with 277V phase to neutral instead of 240V, that would preserve the option to implement the three phase in the future.