The beauty contest is over. Unfortunately, we don't know the winner. Bob Lutz, chairman of General Motors, said in a press conference in Joliet, Ill. that the automaker has decided on a battery maker for the Chevy Volt, the hotly anticipated plug-in hybrid coming toward the end of 2010. Lutz, however, didn't say which of the two battery makers GM is working with has selected. The money-losing automaker has been working with two vendors: Compact Power, whch is a U.S. based subsidiary of South Korea's LG Chem (Life's Good with Chemicals) and Continental Automotive Systems. Continental has been working with A123 Systems. GM is also an investor in A123. For A123, the Volt contract is a make or break moment. The battery developer filed documents earlier this month to hold a $175 million IPO. It generated $41.3 million in revenue but posted a $31 million loss last year. The company's largest customer right now, Black & Decker, cut back purchases in the first quarter. In all, A123 has raised $132 million. Being part of the Volt contract would give the company the opportunity to drastically grow revenue. The batteries in plug-ins are a lot bigger and more expensive than those in power tools. Consumers and policy makers have also gone bonkers for plug-ins. If GM builds a decent car, it could go a long way toward reversing the company's fortunes. I saw a prototype last year in Los Angeles and spoke to Andrew Farah, one of the chief engineers on the project. GM has clearly taken this seriously and wants to have a hit. It's not a half-hearted effort. On the other hand, if GM goes with brand B, there will be a flurry of people writing the A123 obit.