12V Battery Runtime Calc

12V Battery Runtime Calc is an offline planning tool for estimating usable battery hours from amp-hours, battery count, load watts, usable depth, inverter loss, and reserve margin. Use it when you need a quick runtime answer before packing gear, sizing a small RV or camping setup, or checking backup time at home or on site. Enter battery size, voltage, battery count, load watts, usable depth, system loss, and reserve, then review usable energy, gross runtime, planned runtime, reserve time, and battery count in one result sheet. Built for narrow field use: - Works offline after install - No account required - No ads or analytics SDKs - Local calculation inputs only Boundary: 12V Battery Runtime Calc is an estimating worksheet only. It does not certify electrical safety, battery health, wiring, charger sizing, code compliance, or emergency backup suitability.