The best utility tool provides comprehensive monitoring for ExtraPower LiFePO4 batteries, including: Wirelessly connect to each battery from your phone(tablet). Track cycle life on each battery. Displays S tate of Charge(SOC) percentage with circle graphic. Displays voltage, charging or discharging current , and temperature. Connectivity distance up to 5meters. Uses Bluetooth BLE 4.0 or later. Compatible with Iphones with IOS 7.0 or later. Only one device connects at one time. Some phones(table