Tesla Motors [NSDQ:TSLA] may be the first automaker to try selling standalone battery packs for powering homes and businesses, but it may not be the only one for long. Mercedes-Benz could soon enter the energy storage business as well. A division of parent company Daimler has been testing battery packs that can power houses or store excess electricity from the grid, and plans to launch commercially in September.

Called ACCUmotive, this division was created in 2009 to develop lithium-ion batteries. Like Tesla before its recent announcement, the Daimler arm has been testing energy storage systems under the radar for some time. It recently built an energy storage array operated by German electricity joint venture Coulomb. The array consists of 96 lithium-ion modules that together boast a combined 500 kilowatt hours of storage capacity, which is used to stabilize the Saxony Kamenz power grid. There are plans to expand it to 3,000 kWh of capacity.

ACCUmotive has reportedly delivered more than 60,000 lithium-ion cells to customers—which may include Mercedes itself—and employs more than 250 people. Now it appears ready to expand even further. Mercedes, together with ACCUmotive, says it is testing battery packs for "light industrial, commercial, and private" applications, in sizes ranging from 2.5 kWh to 5.9 kWh. Individual packs can also be combined to provide more storage capacity for a given site, the company says.

While Tesla's decision to get into energy storage seems somewhat logical given the connection to its existing electric car business and Elon Musk's SolarCity, Mercedes' decision appears less straightforward. Tesla's plans are partially fueled by the massive battery 'Gigafactory' it's already building in Nevada, primarily to provide lithium-ion cells for the upcoming Model 3 electric car. Mercedes offers the B-Class Electric Drive, Smart Fortwo Electric Drive, and a growing range of plug-in hybrids, but it probably isn't aiming for the same volumes. It also doesn't have a Gigafactory of its own to churn out large numbers of cells for both electric cars and energy storage. But given its high-profile brand name, Mercedes could offer some competition for Tesla in the growing energy-storage market.


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