Absorbent glass mat batteries are lead-acid batteries in which mats of glass fibers are sandwiched between lead plates. Because the glass fibers soak up the batteries' electrolyte fluid, the batteries won't spill, even if damaged.
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 gasoline-powered 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.
Despite the cost, lithium ion batteries have generated interest among automakers. In early 2010, Porsche started offering an optional lithium ion starter battery for the Porsche 911 GT3, 911 GT3 RS, and Boxster Spyder.
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."