How much battery does a refrigerator need?
A refrigerator has two different needs: enough stored energy to last, and enough output to start its compressor. Check both before you choose a battery.
Start with energy, not the plug label
A nameplate describes an electrical rating. It does not tell you how much energy the refrigerator will use across an entire day. A compressor cycles, and a defrost heater can add another load. A plug-in energy meter that records watt-hours over a representative day gives you a more useful starting point. Follow the meter and appliance ratings; do not use an unsuitable adapter.
A worked example
Suppose your measured use is 1,200 Wh per day. A 12-hour outage would represent about 600 Wh if consumption were evenly distributed. At an assumed 85% conversion efficiency, that is about 706 Wh from the battery. Add an assumed 8 W of inverter idle draw for 12 hours (96 Wh), then a 20% planning margin: (600 ÷ 0.85 + 96) × 1.20 ≈ 962 Wh. This is an example, not a specification for your refrigerator.
Then check the start
The battery’s continuous AC output must support the refrigerator while running. Its surge specification, including the permitted duration, must support startup with any other connected devices. The planner’s refrigerator starting value is only an editable illustration. Measure startup with suitable equipment or get requirements from the appliance manufacturer. A large capacity number does not settle this check.
Plan for the actual conditions
A hot room, frequent door opening, and defrost cycles can change consumption. If you use an annual EnergyGuide figure, divide kWh per year by 365 and multiply by 1,000 for an average Wh-per-day estimate; it is still a standardized average. Keep a refrigerator thermometer and follow food-safety guidance after an outage. Battery runtime is not a food-safety guarantee.
Sources & further reading
- Virginia Tech: estimating appliance energy use ↗
- DOE: refrigerator energy-use and EnergyGuide data ↗
- FoodSafety.gov: food safety in an emergency ↗
Numerical examples and default device values are illustrative unless explicitly described as a measurement. Consult the manuals for your own equipment.
Make it a plan for your home.
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