Short answer
For a fridge, do not choose only by headline capacity. Check continuous output, startup surge tolerance, usable watt-hours and how many hours you need the fridge protected.
- Small fridges often run at low average wattage but start with a short compressor surge.
- For overnight backup, look at usable energy, not only the number printed on the box.
- For hot kitchens, commercial fridges or freezers, move one model class higher.
