The Electric Car's Perfect Plug - Choosing the Plug for Electric Cars - Popular Mechanics

The Electric Car's Perfect Plug - Choosing the Plug for Electric Cars - Popular Mechanics: "The most noticeable difference in the new model is at the end of the cord: the prongs. The traditional three-prong plug will be replaced with a five-prong plug, so current electric vehicles will need a converter or owners will have to replace their car's socket entirely. The two additional prongs allow charging stations and vehicles to communicate with each other—a capability that common electronics now lack. 'The devices on both sides of the connector are not just dumb things like a light bulb,' EPRI's Alexander says. 'Both sides have intelligence.'

The cord gains its intelligence through 'smart-grid' technology that monitors energy efficiency, now being installed by utilities nationwide. Car batteries will negotiate how much electricity a local grid should flow its way. That grid, meanwhile, will recognize the batteries' power limit to prevent overloading the circuit. It can also divide its power appropriately between multiple cars if they all plug in at once."