Stephen Edelstein for Motor Authority:  Tesla Motors 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, according to Australia's Motoring.

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.