Spaziou tools · Cooling and cooking
Your fridge's energy consumption.
A compressor fridge does not draw rated power continuously for 24 hours. This calculator applies a duty cycle for a more realistic estimate.
Duty cycle changes with conditions.
Ambient temperature, compressor ventilation, temperature setting, food load and door openings can substantially change use. Treat duty-cycle percentage as a scenario, not a universal constant.
From cooling needs to battery size.
Use the result to calculate the battery runtime then compare equipment with consumption and capacities suited to your trip.
Method · Example · Decisions
Measure a fridge's daily energy use
Compressor running power and daily energy use are different quantities. Duty cycle is the fraction of time the compressor runs.
Formula used by this tool
Wh/day = running W × connected hours × duty-cycle fraction × (1 + reserve). Equivalent Ah = Wh/day ÷ voltage. Compressor operating hours = connected hours × duty-cycle fraction.
Reproducible example
45 W connected for 24 hours, a 50% duty cycle and a 10% reserve give 594 Wh/day: 49.5 Ah equivalent at 12 V. Without that reserve, the scenario is 540 Wh/day. This is not a measurement of a specific model.
Do not apply duty cycle twice
If the fridge stays connected for 24 hours and the compressor runs for about 12, enter 24 hours and 50%. Entering 12 hours and 50% would halve active time again. If you already measured a complete day in Wh, use that in your overall energy budget.
What affects actual consumption
Ambient temperature, interior setpoint, compressor ventilation, door openings and food load change duty cycle. A fridge with a freezer or one cooling warm food may need a different scenario. Measure a typical day and a more demanding one.
Are these Ah the battery capacity I need to buy?
No. Those Ah express daily energy at the selected voltage. Battery sizing also needs all loads, days without recharging, usable fraction and losses. Use the battery calculator for that part of the design.