Automakers are expected to vote this week on a standard for cables and plugs that will be used to charge plug-in hybrid and electric cars.

The Society of Automotive Engineers has been working on the standard, called J1772, for the past two and half years, and it is expected to take a vote this week, said Britta Gross, director of global energy systems, infrastructure and commercialization at General Motors, over a web chat Tuesday.

"All major automakers are expected to agree to adhere to these charging standards. All infrastructure that goes in from now on should be J1772 compliant so all plug-in vehicles can use it," Gross wrote.

The vote may not be a final one – the process of setting electrical and performance specs takes time and often undergoes many votes. If there are no objections to the technical specs during the vote, then J1772 would become official standard and published in about 10 weeks, said Gery Kissel, a GM engineer and chairman of the J1772 committee. 

As carmakers get ready to launch plug-in hybrid or all-electric cars next year, they will be facing questions from consumers about the logistics of operating and fueling these cars.

The questions posed to Gross and fellow co-host of the webchat, Mark Duvall at the Electric Power Research Institute, provided a glimpse of the kind of inquiries that GM, Toyota, Nissan and others will have to answer as they set out to convince the public the merit of cars that use little or no gasoline.

GM is launching its first-ever plug-in hybrid, the Chevy Volt, in late 2010. The car could be charged with the 120-volt or 240-volt outlets, which could take eight hours and three hours respectively to fill up a depleted battery.

Many questions centered around the charging technologies and the performance and lifespan of the lithium ion batteries.

In particular, some participants wondered if charging cars at different rates would somehow damage the batteries. Plug-in or all-electric cars can be charged using a standard 120-volt or 240-volt outlet that can be found at home. Although the proposed standards technically would make it possible to directly plug into a 240-volt outlet at home, Duvall said an additional connector is desirable for safety reasons. 

"We're still studying this to see if there is any significant or perceptible difference in impact to the battery from different charging rates," said Gross.

Duvall said the same is true for the impact from fast-charging technologies, which are largely in the development and demonstration stages.

Some companies are working on technologies that can fill up a battery at five or even 10 times the rate of regular charging. Some are aiming for doing it 50 times faster. But not all plug-ins will be able to tolerate fast-charging, Duvall said. Car owners also will have to pay extra to get fast-charging equipment.

"This [50X technology] would likely have significant impact on battery life, and only certain battery technologies could even do it. We still have more work to do to fully understand this," Duvall said.

Another participant also wondered whether the lifespan of a battery would be shortened if a driver recharges it often instead of waiting for the battery to be nearly depleted before filling up.

"Incremental battery charging should not decrease the life of a lithium ion battery.  In fact two shallow recharges are probably a little easier on the battery than a single deep recharge," Duvall said.