To calculate runtime, convert the battery’s amp-hour (Ah) rating to watt-hours (Wh) by multiplying by its voltage (e.g., 12V x 100Ah = 1200Wh). Divide this by the appliance’s wattage (3000W). Without considering inefficiencies, 1200Wh /… Understanding the Runtime of a 100Ah Battery with a 3000W Appliance