42-Volt Electrical Systems
Auto electron juice to get a voltage boost
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by Cathy Nikkel/autoMedia.com
Ever-expanding creature comforts, safety technology and telematics are maxing out the venerable 12-volt auto battery. "Increased demands on vehicle systems for high-tech gadgets—like cell phones, Internet connection and navigation systems—increase the engine's burden, resulting in more gas consumption and emissions," says Rick Johnson, chairman of the Storage Battery Standards Committee of the Society of Automotive Engineers. If the standard auto battery had more voltage, it could cut fuel consumption by 10%, reduce emissions and add the punch needed for the explosion of electronic technology under the hood. The old-style belt-and-pulley mechanical systems would be replaced with electrical systems that do not drain power from the engine. A massive 42-volt battery system is on the horizon and predicted to be cranking out current in 35% of all vehicles by 2010, according to Standard and Poor's.
The first step in the evolution could be a 2-battery system, pairing a 12-volt and a 36-volt battery with a DC-to-DC converter that would allow the voltage to be stepped down for devices still operating on the 12-volt system.
VRLA Tech
The most viable configuration for a 42-volt battery system is a valve-regulated lead acid (VRLA) design with enhanced performance. The VRLA is a sealed, leak-proof, long-life battery that doesn't produce gas, so it doesn't need to be confined upright and under the hood. Like other lead-acid batteries, it uses an inexpensive lead, plastic and electrolyte solution of sulfuric acid and water, and can utilize an established manufacturing, distribution and recycling infrastructure.
European automakers are taking the lead in the VRLA technology. Consumers of luxury vehicles probably will be able to purchase a German car with a high-voltage battery system in 2002 or 2003. BMW has prototypes now and could put the technology on the market by as early as 2002. In the U.S., General Motors has a 42-volt program team and is already well into the development process. (GM's EV1 electric vehicle was the carmaker's first attempt to implement the higher-voltage technology.) Ford is expected to initially develop a dual system of 12-volt and 36-volt because it will fit within the current infrastructure. (Changes needed for a 42-volt system include service tools, parts, aftermarket components, educating technicians and consumers, new supplier capabilities, and standardization.) Both Ford and BMW believe that the first vehicle to be powered by a 42-volt system will come in late 2003 or 2004.
Safety Concerns
Safety is a concern with 42-volt power systems. The current 12-volt system slips just under the threshold of 15 volts when persistent arc discharge becomes a problem. Sparking between electrical contacts happens in today's batteries, but it is unstable and easily broken. Up the voltage to 42, however, and you get an arcing effect that can generate temperatures above 1,832 degrees F. If generators vibrate loose or a car owner accidentally disconnects a live wire or a switch becomes faulty, a fire hazard develops.
Relay arcing is another problem inherent to 42-volt systems, raising the concern for possible vehicle fires. Higher power relays, switches and fuses need to be developed for these systems. It may take a new connector system in the car to handle electricity safely on the high-voltage system.
"Hundreds of automotive components will need to be reengineered to become 42-volt adaptable," says Norm Traub, Director of the SAE Strategic Alliance (SSA) 42-Volt Initiative. "Batteries, circuit protection devices, switches, wiring harness—you name it—will need redesigning. Dual-voltage systems (14- and 42-volt) will be designed as an interim solution. And there are service and repair issues associated with 42-volt. Technicians will need to be retrained and new diagnostic systems developed.
"It's a huge undertaking, but it must be accomplished. Consumers want advanced safety, entertainment and communication features in their vehicles, and 14-volt systems cannot deliver enough electricity. Forty-two-volt systems will become a prerequisite for improved safety, comfort and convenience, as well as regulatory requirements for reduced emissions and fuel consumption." |
