7650 Add-A-Battery Kit - Boxed Packaging. The 7650 Add-a-Battery simplifies switching and automates charging for a complete two battery bank management solution.. Features:. A complete two battery bank management solution. Dual Circuit Plus Battery Switch isolates engine and house circuits, and combines battery banks for emergency starting. The 120 Amp SI ACR automatic charging relay combines for charging. 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.