Fridge power planning
Keep the fridge cold.
Check the real load.
The compressor’s running wattage is only part of the answer. How often it runs—and what your station consumes while waiting—can change the result.
Measure a representative day
Use an appropriate meter to record energy over 24 hours in conditions resembling your trip. Note the temperature setting, ambient conditions and how often you open the fridge. Convert kWh to Wh by multiplying by 1,000. For DC measurements, use equipment suitable for the circuit and follow its instructions.
If you only know compressor-on wattage, estimate compressor running hours rather than multiplying by 24 automatically. A hypothetical 45 W compressor running for eight hours uses 360 Wh. That example is not a promise about any fridge.
Estimate runtime from usable energy
Using the example above and an assumed 85% delivery efficiency, the fridge draws about 424 Wh from the battery per day, before any extra station overhead. A nominal 1,000 Wh battery would then suggest about 2.36 days with no reserve. Adding 120 Wh/day of measured station overhead reduces that estimate to about 1.84 days.
Those are arithmetic examples, not tested runtimes. Reserve, battery condition, temperature and actual conversion behavior all matter. Add your other devices before selecting capacity.
Check the connection
A compatible regulated DC connection can avoid running an AC inverter, but check the fridge’s voltage and current requirements, port limits, cable rating and connector fit. Confirm that any automatic low-load shutdown will not interrupt normal cycling.
Reduce uncertainty before leaving
Run the complete setup for a representative day before the trip. Keep the fridge ventilated according to its manual, use your intended settings and record the energy. Plan for less solar production than an ideal sunny day when your trip depends on it.