A technology that promises to help give the auto industry a New Economy image is going to be done in stereotypical Old Economy fashion — slow and staggered.

The conversion of vehicle electrical architectures from 14-volt to 42-volt, which will allow for key performance upgrades and turn cars and trucks into rolling office and entertainment complexes, may take 20 years to fully complete. And it will require among most automakers a costly transition period when vehicles will have two batteries, because some components won't be ready to handle the increased power, industry insiders say. “We wanted to make one jump and keep just one battery,” says John Miller, the lead engineer on Ford Motor Co.'s 42-volt product development program. “But you'd have to expect everybody in the industry to retool at the same time.”

The first vehicle to offer a power system featuring 42-volts should debut next year in Europe followed by North America in 2003. A Standard and Poor's study says 25% to 35% of vehicles in North America, Europe and Japan will have 42-volt systems by 2010. Around 2012, dual voltage systems will peak. By 2020 or so, all cars and trucks should have a single battery, 42-volt architecture. That's not exactly an expeditious changeover. But the wait should be worth it.

The introduction of 42-volt technology into cars and trucks stands as automotive engineering's biggest feat since at least the 1970s when gas shortages pushed the industry to make major fuel economy improvements in less than a decade. Some will argue it's been longer than that. “Nothing really has taken the industry to this level of magnitude in the last 40 years,” reasons Joe Fadool, director of North America Programs, Siemens Automotive Body Electronic Systems.

Once again, fuel economy is a reason. But this time it's not the only incentive. Vehicle power consumption presently is about 2 kW. Current 14-volt systems have hit critical mass, especially in feature-laden luxury vehicles. It's preventing automakers from adding more infotainment equipment and performance improvements such as steer-by-wire and brake-by-wire. By 2010, vehicle power consumption is expected to be 6 to 8 kW.

In most cases, automakers are planning on using 42-volt technology initially to combine the starter and alternator into an integrated starter-generator (ISG) unit. Best described as a second engine, an ISG isn't practical without a 6 to 8 kW power requirement. It will be mounted on the crankshaft between the engine and transmission, and is expected to provide fuel economy gains of 10% to 20% by producing power while idling, accelerating in low-speed range and converting kinetic energy to storable electric energy when braking.

After an ISG is added, more systems are introduced. “It's going to be a gradual build-up of components,” says Jean Botti, director of Delphi Automotive Systems' Customer Solutions Center.

For instance, electronic throttle control will more accurately gauge input. Electronically operated valves open the door to a variable-displacement engine that accelerates with all of its cylinders but cruises with only some. Engineers will even be able to vary cylinder firing to maintain cylinder wall temperatures.

What's more, An ISG will diminish the demand on the internal combustion engine. In today's vehicles, about 80% of the energy going into the engine never makes it out of the driveline because it is sucked away by internal friction, heat loss and components such as the air conditioning compressor, water pump, power steering and rear defrost. An ISG will power auxiliary electric drives so these parts run independently of the engine and can be more effective. Rear defrost, for example, will be able to provide good clarity in three minutes or so in 20½F (-6½C) instead of six or seven minutes.

So what's the hold up? The last time the auto industry increased vehicle architecture voltage it took only about 10 years during the 1950s and 1960s. The answer: cost, design complexity and component readiness. Automakers are dealing with five to eight times more electrical components on a vehicle than they did 50 years ago. There's also the issue of where to locate the second battery. “If you're carrying a dual system, there's going to be a cost hit to the (vehicle) program,” explains Mr. Fadool.

For BMW AG and other automakers going straight to a single battery 42-volt system, a converter will have to be used until lighting and other sensitive components that might be fried by the higher voltage can be replaced. And while a 42-volt architecture will reduce costs for some things, including solenoid-operated devices and motor-drive circuits, it will increase expenses for relays, switches and coil winding. Some automakers are wary about pressing forward too fast because the cost is going to have to be passed on to the public, most of whom probably won't be enthralled with the thought of paying extra money for something as unglamorous as a new battery. “It's going to be the revolution by evolution,” says Mr. Botti. “It can be a good position to be a fast follower.”