PARIS – Industry engineers and governments in France and Germany agree there should be a single plug and socket for charging electric vehicles in Europe, but they have yet to reach agreement on a standard.

While most major auto makers would like a global standard, it is unlikely to happen, as Japan and the U.S. already are moving toward their own protocols. And even if Europe reaches agreement, wall sockets differ from country to country within the continent.

At stake in the debate is the public’s acceptance of EVs and plug-in hybrids. Or as Renault SA project engineer Philippe Dupuy puts it: “How many cables will you have in the trunk?

In the interim, infrastructure projects are moving ahead using connecters in charging stations that later may have to be replaced.

In Germany, auto makers have joined in support of a 7-point connector made by Mennekes Elektrotechnik GmbH & Co. KG, and German electric-utility RWE is in the process of installing 500 charging points in Berlin for a Daimler AG demonstration using Smart EVs.

In Strasbourg, France, French utility EDF will install 400 charging stations using a common type of connector found on recreation vehicles in campgrounds for a plug-in-hybrid experiment that will see 100 Toyota Priuses launched next year.

French auto makers Renault SA and PSA Peugeot Citroen agree there should be a standard connection, but they disagree on what kind. Renault supports the German solution, while PSA wants something less onerous.

Meanwhile, Volvo Car Corp., in partnership with the Swedish electric-utility Vattenfall AB, plans to launch a PHEV in 2012 that uses a standard domestic wall socket.

EDF’s Patrick Gagnol, who is part of an international working group trying to come up with a single solution, opposes the use of household wall sockets in France, noting current fluctuates at around 10 amps, while sockets such as those in Strasbourg provide a steady 16 amps.

More importantly, household sockets are not rugged enough to be plugged into several times a day. However, “it’s not a war,” he insists. “For the moment, we are working on the technical questions of how to recharge a battery from the network.”

For slow-charging situations, EV owners would plug a cable into the car and into the charging outlet. A normal 230-volt, single-phase 16-amp household current in Europe will recharge most PHEVs being developed by auto makers in seven or eight hours, which is expected to be the norm, most industry players agree.

But fast charging is at the heart of the debate.

At Daimler, “we believe in low-cost fast charge,” says Brian McKee, manager of strategy for Mercedes-Benz. “What we want most of all is a public charging infrastructure everywhere you go.”

And even if customers drive less than 37 miles (60 km) a day and slow charging at night is all they need, “we must have an answer for the exceptional situation,” says Renault’s Dupuy. “We have to get a suitable infrastructure, so we can say to the customer that there is no limitation.”

But fast charging will create heat, require special heavy cables and, if used often, will shorten the life of an expensive battery, says Bernard Sahut, PSA’s innovation sub-domain manager. The auto maker believes the goal during the introduction of EVs should be to keep things simple.

Says PSA’s Anton Grivaux: “The first EVs we sold, people had the option of fast charge or not. And 95% chose the option, but only 1% used it. They all used existing connections. In Scandinavia, people plug in their cars in winter into a standard socket to keep the engine warm. The infrastructure is already there.”

Germany’s Mennekes RWE connector is aimed at serving in all situations. Its seven wires include two small ones for communication and five thick ones: three phases, a ground and a neutral. An EV or PHEV could recharge at 3 kW, the normal one-phase slow charge, or more expensive multi-phase fast charging at 10, 20, 30 or 43 kW.

For Daimler’s McKee, the plug is a done deal. “We worked with auto companies to develop a standard plug,” he says. “We are going to implement it in Berlin. It is a world record for moving from concept to implementation in a little over a year. It will handle 63 amps and 43 kW of charging power.”

French-utility EDF’s campground socket conforms to the IEC 60309-2 standard. There is a normal version for 16-amp connections and a larger, high-power version for a 63-amp connection.

A £30 million ($49.5 million) infrastructure project in the U.K., like the EDF’s in Strasbourg, is likely to use the 16-amp single-phase 60309 connecter already employed at some shopping centers and car parks in London, says the U.K.’s Evan Tuer, who follows the EV industry.

Besides the question of what the connection to the network should look like, there is the issue of what the connection to the car should be.

“You need a (common) plug at the network, and the cable to the car could be different for each auto maker,” Gagnol says. “There is no need that the connection at the vehicle be the same.”

However, German auto makers argue the same connection should be at each end of the cable.

Fast-charging stations, which are likely to be fewer and located in protected, enclosed areas for safety, could have a charging cable affixed to the station. In that case, the connection to the car would have to be standard. If the RWE connection is the standard at the car end and the charge station, there would be no problem.

Tuer believes slow charges could be done with a 60309 socket at the infrastructure end, and an RWE socket at the car, whereas fast charge could be handled by the station’s built-in cable with an RWE connecter at the end.

“Those connections will cost €150 ($225) each,” says PSA’s Grivaux. “What will they say when someone drives over their plug in the garage and they go to the dealer for a new one (that costs) €300 ($450)?”

Argues Gagnol: “A more complex connection will allow more safety functions to be added” and will permit the kind of smart-grid communication, where billing, timing of recharges and battery monitoring can all be handled by car-to-grid communication.

The working group on the plug and socket hopes to have a first draft on the function, maximum power and geometry of a connector by first-half 2010, Gagnol says. After that, a proposal would have to go through the administrative procedures of the ISO and IEC standards organizations and could require new government regulations.

Today, the RWE socket would be illegal in France, because it does not have built-in child proofing. So even if the EV world is moving fast, it would not be surprising to see full standardization take a slower route, arriving later than sooner.