Traveling on the bumpy, iffy road from 14 to 42 volt auto electronics systems - Embedded.com

Traveling on the bumpy, iffy road from 14 to 42 volt auto electronics systems

What happened to the 42V automotive system?

The fast track to the more powerful standard did not materialize aspredicted, and no one is talking about a quick adoption in the future.In fact, some experts have predicted that it won't happen at all.

The optimization of 14V architectures and components, includingtechniques for distributed power network stabilization, has extendedthe life of 14V systems.

However, at some point in the future, system performance factorswill compel carmakers to finally shift to 42V. Suppliers of electronicand electrical components need to be prepared to support thisinevitable transition.

As automotive electronics and electrical content continue to expand,manufacturers are faced with the greater task of ensuring theavailability of sufficient power.

This growth in content – fueled by the addition of new comfort andsafety features as well as systems to enhance fuel economy, emissionsand driveability – began in the 1990s and is forecast to continue inthe next 10-15 years.

Figure1. Technical challenges and added cost outweigh the benefits of a 42Vsystem at this time.

Implementation of these electronic functions and features requires achange in the way automobiles distribute and manage electrical power.These new electronics provide the fundamental driving force forswitching to a 42V system.

Why 42 volts?
The benefits offered by a higher-power electrical system include:

1) Enablingadditional accessory power requirements that exceed the capabilities of14V systems;

2) Improved powermanagement capabilities and system stability;

3) Reducedelectrical current levels;

4) Reduced mass,volume and cost with downsized electrical wiring and components, aswell as the replacement of mechanical systems with electrical systems;

5) Increased fuelefficiency;

6) Reducedvehicle noise, vibration and harshness (NVH).

Table 1. Implementation ofelectronic functions and features requires a change in the way carsdistribute and manage electrical power.

So, why is 14 volts still here?
These benefits seem to provide a reasonable argument for rapid adoptionof the 42V standard.

However, the reality is that engineering modifications and enhancedcomponent capabilities have extended the life of the current 14Vstandard for now.

Through improvements in the efficiency of electrical components,architectural modifications to optimize functional integration at thesystems level and distributed methods of power network stabilization,automakers have delayed the need for a wholesale change to a differentpower system standard.

Additionally, there are many economic and technical challenges thathave inhibited practical implementation of 42V systems. These includethe replacement cost of component technologies and an infrastructureoptimized for 14V; long-term reliability concerns at higher voltage andpower levels; safety issues; and component and conductor arcing.

At present, the technical challenges in implementing the 42V systemcombined with the added cost outweigh the benefits.

The road ahead
As observed, it isn't a simple matter of one or two factors determiningthe outcome of the 42V system. The move has been a complex combinationof factors that must be balanced to make the right decisions.

Yes, the 14V power network will not be capable of maintaining thepower performance required at some point down the road as electricalcontent continues to grow.

Yes, there are many good reasons to change over to 42V, rangingfrom fuel economy and emissions improvements to enabling implementationof advanced safety features.

However, there are also good reasons to stay with the status quo.The lack of a clear-cut move to 42V has resulted in the need to splitresources on new development.

Electronics suppliers must continue to develop and improve productsfor use in traditional 14V systems. At the same time, they must lookahead to the technical advances and products that will support the 42Vsystems of the future.

Figure2. As relative cost decreases and electrical content grows, the rate of42V system adoption will gain momentum.

Pros and Cons
What are the pros and cons? First, there is no technical challengeposed by 42V systems that cannot be solved. The real issue is cost,particularly as it compares to the current 14V system.

<>For example, 42V system batteries capable of offeringcomparable lifewith current 12V batteries require more costly technologies, such aslithium or nickel-metal hydride, to implement. Arcing and corrosionissues can be addressed through the addition of battery disconnectswitches and sealed connectors at an added cost.

Suppliers will continue to improve technology to reduce the cost ofsolving the technical challenges. At the same time, the applicationsfor electronic and electrical systems will continue to grow. As therelative cost of 42V systems decreases and the electrical contentgrows, the rate of 42V system adoption will gain momentum.

Supplier challenge
For suppliers of electrical and electronic components, what does thecurrent situation entail?

Companies must continue to both optimize the capabilities of 14Vsystems and address the challenges of 42V systems. This must be done onrealistic R&D budgets that reflect the economics of our times.

Thus, a coordinated effort in technology and product developmentmust be made to ensure the most effective use of limited resources.

Gary Wagner is director of BodyElectronics and Scott Irving is Automotive SegmentDirector at FairchildSemiconductor. For a PDF version of this article, go to Gearup for the shift to 42V systems.

Reader Response


One reason no one wants high voltage car batteries is that they present a life-threatening hazard.

Twelve volts is tolerable to a human standing in a puddle in the rain, trying to get a jump start. 42 V might be fatal, especially into an abrasion caused during an attempted repair.

Who's going to pay the funeral expense of this bright idea?

–John Williams
Senior Adjunct Faculty
Silicon Valley Technical Institute
San Jose, CA


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