The electrical and electronic content of cars continues its upward trajectory. Already estimated at a quarter of the content value of vehicles, it is felt that by 2010 some 40% of a vehicle's cost base will be accounted for by its electrical power and control systems. But just what has happened to the 42v revolution? Dennis Foy reports.

Replacing mechanical connections
So far as body engineering is concerned, this increase is being driven by a number of different dynamics, which can be broadly split into the two sectors of ecology and safety. The former is geared to providing the optimum fuel efficiency from an engine, allied to the sometimes-incompatible need to minimise harmful or undesirable compound gas emissions. The latter is a broader-still spectrum, which encompasses such elements as suspension and braking stability, speed-distance control systems, and advanced steering systems.

At the same time that electrical and electronic content is being increased, there is a symbiotic demand from auto makers to reduce the kerb weight of vehicles, and one way that this is being achieved is by increasing the amount of electrical/electronic control in place of mechanical connections. Replacing the 'traditional' mechanical-hydraulic power steering pump with an electronically controlled, electrically actuated power assistance unit reduces engine load, but more significantly reduces not just vehicle sprung weight but also reduces complexity of installation on the production line.

Mandated physical linkages
Were it not for a mandated requirement for the steering wheel to be physically connected to the road wheels, it would be possible to take the technology a stage further, and eliminate the steering column linkage. Similar legal requirements are in place, which constrain the amount of development allowed in braking systems, which at present must retain physical connection between the driver and vehicle hubs.

Benefits of increased electronic control
Whilst there is much to be said for the weight that can be shed and efficiency which can be increased from the adoption of electronics, there must at the same time be an economic advantage to the carmaker which acts to at least compensate for the additional costs involved. This can be achieved in part by the improved packaging of sub-assemblies by external suppliers - which makes for easier stock control and increased ease of installation - and also by allowing reductions in lead time accorded to designers and engineers.

A further benefit of moving to increased electronic control of functions and systems is that it allows automakers to increase the degree of outsourcing involved in each sub-assembly, which can again reduce the in-house element of new programme development costs. It has been unofficially estimated that each hour saved in the period from Job One to On Sale dates can be broadly equated to one dollar off the showroom sticker price of a mid-range new car model.

Finally, increased electronic control allows model specification differentiations to be made quickly and easily; by simply adjusting the control software the level of functionality in any given system can be adjusted to suit the range position and price point of specific models, providing the bare minimum in entry-level vehicles and full functionality in high-series cars.

Role of the sub-contractor
This increased reliance on supplied-in sub-assemblies places increasing importance on the role of Tier One and Tier Two sub-contractors, and allows those organisations to work both separately and together to provide increasingly sophisticated responses to the demands of the industry as a whole. This means not just the designers and engineers, but also the marketing organisations, the cost control units and the other elements that help make up the whole. Even consumer organisations can be included in the picture, as they, whether as safety campaigners or as bargain hunters, have a role to play in today's auto industry.

As a consequence of this increased reliance on sub-contractors there is scope for organisations that have hitherto had little or no involvement in the auto manufacturing process to become active. This is especially true of microprocessor manufacturers and software houses, which have begun to sniff the scent of business opportunities that exist in the automotive industry.

42v - the spectre at the feast
The increasing demands on vehicle electric architecture led the industry to conclude a decade ago that something major needed to be done; in essence the 14.2 volt system which has been in place since the 1950s is no longer adequate to support the dramatic ramping-up of electrical content. The solution was determined to be a wholesale change over to a 42-volt architecture that would provide several times the capacity of existing systems - sufficient to drive the most complex active suspension, electrically assisted power, electrically powered engine valve-train and automatic stop-start systems.

What happened to the 42v dream?
At the turn of the millennium, proponents stated with some confidence that systems would start to arrive by the 2005 model year. Yet here we are, with 2005MY cars beginning to appear in showrooms, virtually none of which have 42v power systems. What is more, there are no indications that 42v architecture vehicles are imminent. Which begs the question: why not?

The answer seems to be a complex blend of existing electrical manufacturer hegemony and raised games that dramatically reduce the need to hurry from 14.2 to 42 volt systems. That, and the high cost factors involved in their adoption; estimates of 20-30% premiums on electrical content exist.

Norman Traub, director of 42v initiatives at the Society of Automotive Engineers (SAE) when asked: "Will we always need 12 volt power on vehicles?" responded by saying that: "Always is a long time, but I believe it will be a very long time before we eliminate the need for some 12v DC power. Incandescent lighting will stay at 12v because of bulb durability and light focusing issues associated with higher voltage incandescent lighting. Incandescent lighting can be controlled by a 42v pulse width modulation technique where the 42v DC is modulated to create a 14v rms voltage."

12v - not dead, yet
But there is much more to vehicle electrical systems than simply the lighting. The shift over to high voltage is considered essential for in-built - as distinct from external, belt-driven - Integrated Starter-Alternator (ISA) -style devices, and is equally necessary for individual valve operations in place of the conventional camshaft. However Tier One suppliers have thus far been able to supply complete sub-assemblies for complex braking systems, electrically-assisted power steering packages, even reactive suspension, that work to the long-established 12 volt DC power system. Increased sophistication in the handling of such chores, by wider use of microprocessors within digital wiring harnesses, is credited with this situation - but this author suspects that this might simply be a little trumpet blowing by the chip makers. Regardless, and mindful that change is inevitable - eventually - Tier One and Tier Two suppliers are ensuring that when the time for change comes, they will not be left behind.

Battery systems
Saft is one of a number of battery manufacturers which is ready for any eventual change, having developed two different battery systems - Nickel-Metal Hydride (Ni-MH) and Lithium Ion (Li-ion) - each capable of being incorporated into vehicles. Of the two the Ni-MH is the more useful contender, given its long cycle life in high power applications; Li-ion is suited for power assist applications and alternator-starters, and according to Saft provides "unmatched specific power and power density". Saft also added, "Thanks to Li-ion's modular concept, customer-specific battery packs can be easily customised." - Inferring that there is a ready market. But is there?

Dual systems
That there is a 42v solution for specific problems hints at a major difficulty facing vehicle manufacturers; there is a need to integrate two completely separate power systems within a single vehicle. This has already been achieved - Toyota managed it as far back as 2001 with the Crown Hybrid, and General Motors has developed two pick-up trucks which have 42 volt integrated starter-alternator-Damper units (ISADs) supplied by Continental - but for the foreseeable future the cost premium of such dual systems is prohibitive to all but the most valuable vehicles. There is a sense of 'who blinks first' about the adoption of 42v systems, and so far it is the world's two biggest manufacturers that have blinked, but they have been cautious in their adoption of higher voltage systems, wisely avoiding direct reference but instead concentrating their marketing strategies on the benefits to drivers.

Toyota promotes the improved economy that automatic stop-start brings, as does the GM campaign, but also adds that: "…there's something Silverado and Sierra Hybrid provide that standard models do not: these trucks are essentially mobile power-generating stations, with four 120-volt/20-amp electrical Auxiliary Power Outlets (APOs). The power outlets are located under the rear seat of the cab and in the pickup bed. Customers can conveniently operate power equipment without taking up the bed space typical portable generators would use." Perhaps most interesting of all, both manufacturers market these vehicles as hybrids - despite their being only partial hybrids as we know them from the Toyota Prius, Honda Civic IMA and suchlike. This suggests that even the automakers are unsure of how best to promote the virtues of 42-volt technology.

The future of 42v technology
The conclusion to be drawn from the protracted birth of this quantum leap in emergent technologies is that the urgency being mooted a decade ago was alarmist, and the imperative for change has receded into the scenery. Perhaps the last word on 42-volt's immediate prospects should go to Denso's R&D Director Masami Manabe, when talking to Automotive Industries, who when asked: "In the electronics area, is 42-volt electrical architecture a development priority?" replied: "We currently supply the 42-volt 'stop-and-go' system for the Toyota Crown hybrid. My feeling is that interest in 42-volt architecture will lessen in the near term due to cost considerations. I expect carmakers to look for cheaper alternatives until around 2008 or 2010 at which time interest will pick up again."

Expert Analysis

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