7649 Mini Add-A-BatteryWhat does the Mini Add-A-Battery do?Adding a second battery prevents getting stranded with a dead battery by isolating the start battery from the house loads that can quickly discharge a battery. The Mini Add-A-Battery offers a compact, simple way to control the switching with the m-Series Dual Circuit PlusT Battery Switch and automatically share a single source of charging between two batteries with the Mini ACR Automatic Charging Relay. WARNING: This product can expose you to chemicals including di(2-ethylhexyl)phthalate (dehp) which is known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.