Portable fridge for a weekend: battery and solar budget
A two-day 12V compressor-fridge setup with lighting and two phones, using an explicit 50% compressor duty-cycle assumption.
Battery target for 2 days
Stated battery capacity, including a 20% extra energy margin on demand and 80% usable energy.
Adjust this exampleThe bundle uses about 700Wh per day and needs roughly 2,100Wh rated capacity for two battery-only days. Daily solar changes the required stored-energy horizon but not the need for poor-weather reserve.
- Energy per day
- 700 Wh Power × hours × quantity
- Power check
- 73 / 170 W Simultaneous / peak — planning values
- Solar target
- 250 W 4.5 peak sun hours · 75% yield
Solar is a separate estimate. The battery target is calculated without intermediate recharging.
Stations to compare first
We check both battery size and whether the station can handle the load. Solar compatibility is still a separate check.
2,100 Wh
Includes days, the extra energy margin on demand and the 80% usable-energy allowance
73 W · 170 W
Verify the exact appliance and inverter together
Verify local voltage, frequency and plug
Exact regional model, compliance route and local warranty still required
The devices in this example
These are sensible starting values. Change the hours and exact devices in the planner to make the answer yours.
12V fridge — daily average
540 Wh per day- Average consumption
- 22.5 W
- Entered peak
- 120 W
- Hours per day
- 24 hours
- Quantity
- 1
LED camp lights
100 Wh per day- Average consumption
- 20 W
- Entered peak
- 20 W
- Hours per day
- 5 hours
- Quantity
- 1
Phone charging
60 Wh per day- Average consumption
- 15 W
- Entered peak
- 20 W
- Hours per day
- 2 hours
- Quantity
- 2
Duty cycle is the largest unknown
At 25% duty the fridge energy halves; at 75% it triples relative to that low case. Hot-weather testing is more useful than a brochure number.
Solar must cover energy, not only watts
A 200W panel can momentarily exceed the fridge draw and still fail to replace a full day’s consumption in weak sun.
Calculation detailsSee the assumptions behind this answer
- A 45W compressor runs 50% of the day
- LED lighting uses 100Wh per day
- Two phones each receive 30Wh per day
- The fridge uses its native DC path where supported
How the battery target is formed
700 Wh per day × 2 days × 1.2 ÷ 0.8 ≈ 2,100 Wh
The daily consumption above is rounded for display. The calculation uses unrounded values. The factor is 1 + the extra energy margin, added to demand rather than kept as battery charge; the 80% usable-energy allowance is a separate factor.