How Long Will a Battery Run a Refrigerator? (Real Math)
Short answer: a modern full-size refrigerator draws roughly 1–1.5 kWh per day (it cycles; average draw 40–60 W, running draw 100–200 W, startup surge 600–1,200 W). Divide usable battery capacity by that and apply ~85% inverter efficiency:
| Battery size (usable) | Typical fridge runtime | Real-world example class |
|---|---|---|
| 0.5 kWh | ~6–10 hours | Compact stations |
| 1 kWh | ~12–20 hours | Anker C1000 / Jackery 1000 class |
| 2 kWh | ~1–1.5 days | EcoFlow DELTA 2 Max class |
| 4 kWh | ~2–3 days | F3800 / DELTA Pro 3 class |
| 13.5 kWh | ~1 week+ (fridge alone) | Powerwall 3 class |
What moves the number
- Surge capability matters more than capacity at the low end. The compressor's 600–1,200 W startup spike trips weak inverters — a station needs roughly 1,500 W rating to run a full-size fridge reliably.
- Door discipline is worth hours. A closed fridge holds safe temperature ~4 hours unpowered; a closed full freezer ~48 hours (per FDA guidance). During an outage, run the battery intermittently: fridge doesn't need continuous power to stay safe.
- Age and size: a 2010 side-by-side can draw 2× a modern efficient unit. Garage fridges in summer run harder.
- Solar input changes everything: even a single 200 W panel adds ~0.8–1.2 kWh/day in decent sun — enough to run fridge duty indefinitely on a 2 kWh station.
The intermittent trick (stretch any battery ~2×)
Power the fridge in 30-minutes-on / 60-minutes-off blocks once it's cold. Compressor duty cycles mean you spend watt-hours mostly on cooling, not idle losses, and a 1 kWh station stretches from ~15 hours toward 24+. Critical caveat: don't do this with a packed-warm fridge after a shopping run.
Sizing for more than the fridge? Add up your real loads in the battery size calculator, and see which stations we'd actually buy.