12-volt battery gets a makeover as automakers shift to more electric parts

As automakers add stop-start to their vehicles, the lowly 12-volt battery is getting a makeover.

Stop-start systems can wear out conventional lead-acid batteries because the engine restarts every time a vehicle with stop-start pulls away after stopping.

Likewise, other newly electrified accessories such as power steering, water pumps, oil pumps and parking brakes are increasing the workload of the 12-volt battery.

So suppliers have designed batteries that can withstand frequent discharges and recharges. At least two types have emerged as upgrades:

• The absorbent glass mat battery is an improved lead-acid battery that is more durable -- and more costly -- than a conventional battery. Johnson Controls Inc. of Milwaukee is a leading supplier.

• A 12-volt lithium ion battery offers more durability and better performance than a glass mat battery, but at a much higher cost. A123 Systems Inc. of Waltham, Mass., aims this product at premium brands.

Absorbent glass mat batteries are lead-acid batteries in which mats of glass fibers are sandwiched between the lead plates. Because the glass fleece soaks up the batteries' electrolyte fluid, the batteries won't spill, even if damaged.

But they are twice as expensive because they take longer to make. The plates must be precisely placed inside the batteries' containers while under compression.

A glass mat battery can provide three times as many cold starts as a conventional battery, says Garth Cole, Johnson Controls' director of global product marketing. It also can recharge more readily, which is useful when the vehicle has regenerative brakes.

And it can restart the engine even when the battery is at a lower charge.

"The primary benefit is the battery's increased ability to cycle," Cole says. "Think about how often you can start or stop during a trip. The vehicle needs that electricity."

In Europe, where stop-start systems are popular, Johnson Controls says its Varta brand -- which markets glass mat batteries plus a less expensive enhanced lead-acid battery -- supplies 80 percent of vehicles equipped with stop-start systems.

Customers include Audi AG, BMW AG, Ford Motor Co., Mercedes-Benz, Volkswagen AG, Volvo and others. In Europe, 70 percent of all new vehicles will have stop-start systems by 2015, Johnson Controls predicts.

But glass mat battery producers won't necessarily get all of that business. In 2013, a German automaker -- as yet undisclosed -- will introduce a 12-volt lithium ion battery produced by A123 Systems.

Originally, A123 developed its lithium ion battery for electric cars and plug-in hybrids. But now the company is marketing a 12-volt version for conventional vehicles.

A lithium ion battery weighs about half as much as a comparable glass mat battery, says Jason Forcier, A123's vice president of the automotive solutions group.

A lithium ion battery also absorbs energy more readily and lasts longer than a lead-acid battery.

But lithium-ion batteries cost at least two or three times more than glass mat batteries, Forcier acknowledges. "We are aiming at the mid to high end of the market," Forcier says. Makers of compact cars "won't pay a price premium for lithium ion."

Despite the cost, lithium ion batteries have generated interest among automakers. In 2009, Porsche AG says it would offer an optional lithium ion starter battery for the Porsche 911 GT3, the 911 GT3 RS and the Boxster Spyder. List price for the U.S. battery option: $1,700, including taxes.

Meanwhile, A123 makes starter batteries for McLaren Group Ltd.

A123 also has development contracts with five automakers, Forcier says.

While a company such as Johnson Controls can expect to produce millions of units, A123 can make money producing relatively low volumes. "For us, 100,000 units and up would be very attractive," he says. "That's the range we're thinking about for the next five to 10 years."