Lithium Power Inc Offers: The 1st available lithium replacement battery for iRobot Roomba 500, 600, 700 and 800 series. iRo...bot Roomba uses Nickel-metal Hydride (NiMH) battery technology in its design. The after-sales market of replacement batteries all use Nickel-metal technology as well. The physical nature of NiMH batteries result in a memory effect and a high rate of self-discharge. These...