Add car-charging to the list of capabilities smart meter maker Itron and demand response provider Comverge want to offer utilities.

The two companies said Wednesday that they've succeeded in an experiment with Michigan utility DTE Energy to control plug-in electric and hybrid vehicle charging systems.

Comverge's Apollo software sent signals through Itron's meters via ZigBee Smart Energy Profile to tell cars to stop charging when the utility wanted to reduce power demand on its grid, the companies said. The same system was able to stop charging when power prices contained in messages exceeded a certain threshold, then re-start charging when prices fell.

Think of it as one of the more forward-looking applications for doing demand response through smart meters, something Comverge and Itron have been working on since this summer (see The Elusive Smart Meter-Demand Response Combo). DTE Energy plans to install about 2.6 million Itron electricity meters over the next six years.

It's one of many experiments underway to control electric and plug-in vehicle charging, which could add huge new demands on utilities. General Motors, Toyota and Nissan plan to start selling plug-in hybrid or all-electric cars in 2010, and more are to come (see Electrification Coalition: U.S. Needs One-Quarter EVs, PHEVs by 2020).

Car charging startups such as Ecotality, Better Place and Coulomb Technologies are promising systems to control charging so it doesn't overwhelm the grid (see The Hidden Player in Electric Cars, Coulomb In Your Garage and Better Place and Ontario Launch Project).

Utilities Duke Energy and Xcel Energy are trying out GridPoint's car-charging technology, and General Motors and Ford are working on systems as well (see Green Light post and Electric Vehicles Could Surpass Grid or Support It).

IBM is working with Danish utility Dong Energy on a similar project, and Comverge has joined a host of partners in Delaware to test out another car-charging platform (see IBM Tests Smart Charging in Denmark and A V2G Test: Pool Electric Cars for Grid Needs).

And Google, has discussed linking its PowerMeter home energy management system to car charging software (see Green Light post).