Micro-battery manufacturer ZPower LLC has signed an agreement to develop a rechargeable battery for use in hearing aids made by a Minnesota company. Terms of the deal between ZPower, in Camarillo, and Starkey Hearing Technologies, in Eden Prairie, were not disclosed. ZPower manufactures rechargeable silver-zinc batteries that it boasts can last all day, but this would be the first time the product would be integrated into a newly developed hearing aid system. Currently, hearing aid patients typically buy systems using disposable zink-air batteries or rechargeable systems using other technologies. “Our rechargeable, silver-zinc chemistry delivers nearly twice the energy of nickel metal-hydride batteries currently used in rechargeable hearing aids,” said ZPower Chief Executive Ross Dueber in a prepared statement. The release, issued this week, did not specify when the product might come to market or its expected price tag. A privately owned company founded in 1996 as Zinc Matrix Power Inc., ZPower has received investments from Intel Corp., PowerVentures, and OnPoint Technologies, a strategic private equity firm funded by the U.S. Army. Silver-zinc technology originally was developed for military and aerospace applications.