Refrigerator Runtime & Duty Cycle Calculator
Standard runtime formulas fail with refrigerators because compressors cycle on and off throughout the day. This engineering tool models thermal duty cycle, ambient temperature derating, and inverter conversion losses.
Why Compressor Duty Cycle Matters
A typical full-sized household refrigerator is labeled at 150W to 250W. If you mistakenly assumed it draws this continuously, you would calculate that a 2,048Wh battery only lasts 8 to 10 hours. In reality, the compressor only runs for 15 to 25 minutes every hour once cooled—amounting to a 30% to 40% duty cycle under moderate ambient conditions.
🌡️ Ambient Temperature
In a hot garage or during summer heatwaves (85°F–95°F), the compressor duty cycle easily jumps to 50%–60%, cutting battery runtime almost in half.
🔥 Defrost Cycles
Every 12 to 24 hours, modern frost-free refrigerators activate an internal electric heating element (400W–600W) for 20 minutes to melt frost, consuming an extra 150–250Wh per day.
⚡ Startup Inrush Current
Single-speed reciprocating compressors require a 1,200W–1,800W surge for 500ms to kick-start against head pressure. Your inverter surge rating must comfortably exceed this.