Car Batteries Are Not Just For the Car Coda Automotive is supposed to start selling its electric sedan next month. On Friday, its parent company announced that it was also moving into a related line: stationary batteries for electricity storage. Coda Holdings will make minor modifications to battery packs for its cars, which use Chinese-manufactured lithium iron phosphate cells, and sell them individually or grouped together - both for storing solar power when homeowners" rooftop panels generate more than they use, and to help businesses reduce their peak loads. Business customers usually pay for electricity on the basis of their highest level of use. Because the packs are designed for cars, they are already modular and thus easy to scale up or scale down. Coda plans to sell its sedan with a battery pack of 31 kilowatt-hours or 36 kilowatt-hours; both numbers are roughly what a suburban house uses per day. The stationary module will be 40 kilowatt-hours. The batteries could also pay for themselves in places where peak-hour power costs more than off-peak power, the company says, although very few places have such "time of use" rates today. Utilities could also use them as backup in areas where demand for electricity has grown and improvements in distribution lines would otherwise be needed. One reason for such growth is the need for juice for electric cars, which raises the idea that the batteries could be charged up in periods of low demand so that they could later be tapped into by car owners to charge similar batteries in the cars. "We are leveraging this technology across business units,"" said Edward A. Solar, senior vice president of Coda Energy, as the new subsidiary involved in battery storage is called. It's synergistic for us. In fact, it also represents a way for the company to hedge its bets. No one is sure just how big the market for electric cars will be. Coda says that using batteries in stationary service will help reduce the emissions that contribute to global warming just as they will in cars. In cars, they replace gasoline with electricity from low-carbon or zero-carbon sources like efficient natural gas plants solar or wind generators or nuclear reactors. But in the stationary market, introducing large amounts of zero-carbon solar power can also lead to carbon dioxide emissions, experts say. The reason is that the energy is highly variable, and utilities, afraid of being caught short if the wind dies or the sun goes behind a cloud, maintain "spinning reserve" - plants that are, in effect, idling but ready to take off at a moment's notice. Batteries could replace some of the spinning reserve. The batteries are designed to accept or give off electricity at very high rates, something not particularly helpful for home use but potentially a good feature for replacing spinning reserve. Each pack is 100 kilowatts, or 134 horsepower. In the past, energy planners have talked about the idea that when electric car batteries start to get old, and have lost, say, 20 percent of their storage capacity, they could go to a secondhand market and be used on the power grid, where 80 percent of the original capacity would still be very useful. But Coda's idea is to use new ones. In fact, the larger batteries meant for cars are attractive for grid use, according to other experts. Last year A123 Systems provided a huge battery storage system for a wind farm in Elkins, W.Va., using millions of cells a little smaller than a flashlight D cell, but executives said their next installation would use automotive-style cells.