What it draws
Chest Freezer
A chest freezer is a better-behaved load than a refrigerator for one structural reason: the cold air does not fall out when you open it, and a full one is a large block of thermal mass that holds itself for a long time without any power at all.
Typical draw, and the number that actually applies
A household chest freezer commonly draws somewhere between 80 and 150 W while the compressor is running. The nameplate on the unit is the figure that applies to yours.
Read the nameplate. It is usually a sticker on the back, inside a door, or on the power adapter, and the figure printed there is a maximum for that specific unit rather than a typical reading. Any range on this page is a starting point for arithmetic, not a substitute for that label.
- Running watts used here
- 100 W
- Duty share applied
- 30%
- Average draw for the estimate
- 30 W
Hours from a 1024 Wh battery
The row stops at 24 blocks; the estimate runs past it. Estimated hours from the reference battery at 30 W average draw. An estimate, not a guarantee.
The arithmetic, in full
hours = (rated Wh x 0.85) / average watts
average watts = 100 W running x 0.3 = 30 W
= (1024 x 0.85) / 30 W = 870 Wh / 30 W
The estimate below applies the duty share before dividing, and assumes a closed lid, a reasonably full freezer, and an ordinary room temperature. A garage freezer in summer will do worse.
The derate of 0.85 covers inverter conversion loss and the share of rated capacity a pack will not hand back. It is one planning figure applied to every unit on this site, not a measurement of any particular model.
Starting surge
Like any compressor, a freezer pulls several times its running current for a fraction of a second when it starts. The inverter must be able to supply that spike or it will fault, which is a separate question from whether the continuous rating is large enough.
Duty cycle
A freezer compressor runs in cycles, and a full freezer in a cool room cycles less than an empty one in a warm garage. This site uses a duty share of 30 percent as a planning figure rather than a measurement.
How to get by without powering it
Every watt-hour you do not spend is one you still have. These are the moves that cost nothing.
- Leave the lid closed. A full freezer holds temperature far longer unopened than any battery will run it.
- Fill empty space with water containers and freeze them ahead of the season. Ice is thermal storage that costs nothing and needs no inverter.
- Group the things you would want to move into a cooler on one side, so the lid opens once.
- Follow published food safety guidance for how long frozen food stays safe and what has to be discarded.
Where this sits in the sequence
This load becomes realistic at stage 3, and not before. Read that stage including the part about what it does not cover, because the limits are the useful half.
Related gear
Products live on the gear pages rather than here, because the decision on this page is about arithmetic and the decision there is about hardware.