A Backup Complete (3 kWh) system can run a typical fridge for roughly 30–60 hours, depending on the fridge's power draw and how often its compressor cycles. A single Core (1.5 kWh) provides roughly half that.
Energy Tip: Using an icemaker, adding new items (especially hot ones) to the refrigerator/freezer, or using the water dispenser will reduce overall runtime. Avoid these less urgent actions to maximize backup time.