Far less than its label suggests, because a compressor cycles rather than running continuously — but how much less depends on ambient temperature, how full it is and how often it is opened. Two days with an energy meter answers it for your fridge in your conditions.
The fridge is almost always the largest single consumer in a vehicle, and almost always the one estimated rather than measured.
Why the label is not the answer
A compressor draws its rated current while it runs, and it does not run most of the time. Multiplying the label by twenty-four gives a figure several times too large, which is how people end up carrying a battery bank they never needed.
What changes the duty cycle
Ambient temperature, first and most. Then the set point, how full the box is — a full fridge holds its cold better — how often the lid is opened, and where the unit sits relative to a sunlit window or a heat source.
How to measure it properly
An energy meter on the fridge’s supply for forty-eight hours, in conditions resembling the trip. The result is a daily watt-hour figure specific to that installation, and it is the only input the rest of the system design actually needs.
What it feeds into
Battery capacity for the nights, solar and DC-DC charging for the days, and a monitor to confirm the plan matches reality once the van is in use. Every one of those is sized from the same measured number.
What people ask before they order
Why do published consumption figures vary so much?
Because they are measured at a stated ambient temperature and set point, and both change the duty cycle dramatically. A figure without those conditions describes a test rather than a fridge.
Does insulation or compressor type matter more?
Both, and they are hard to separate from outside. What is measurable is the daily energy the unit actually uses in your van, which is the number the battery has to cover.
Last reviewed 16 September 2026