PRO Charging Systems Battery Optimization System (B.O.S) Electric Motor Accessory - This is the perfect companion device to utilize with PRO Charging Systems advanced battery chargers. Models: BOS12V2 for two 12V batteries in series (24V system) BOS12V3 for three 12V batteries in series (36V system) Compatible with PROView Link battery monitoring software Enables you to monitor your battery status via your smart phone or tablet. Approved for use with Wet Cell, AGM and Lithium Ion batteries Designed for 12V batteries Designed for use in fresh and saltwater BSAP-24 Battery Selection and Prediction Algorithm on board Less than 1mA sleep mode