Start with watt-hours, not a product name.
Add the energy used by every appliance in one day, extend it across the trip, subtract realistic solar recovery, then allow for efficiency losses and a reserve. Check continuous output and startup surge separately.
Capacity and output solve different problems
A portable power station has two headline numbers. Capacity, measured in watt-hours (Wh), describes how much energy the battery stores. Output, measured in watts (W), describes how much power it can supply at one time.
A large battery can still be unsuitable if its inverter cannot start your appliance. A high-output station can also run flat quickly if its capacity is too small. Your shortlist needs to clear both targets.
Step 1: calculate daily energy
For each appliance, use:
Duty cycle matters for appliances such as compressor fridges. A 45W fridge does not normally draw 45W for every minute of the day. If it runs for roughly 35% of the time, its example daily load is 45 × 24 × 0.35 = 378Wh.
| Example load | Input | Daily energy |
|---|---|---|
| 45W camping fridge | 24 hours × 35% duty | 378Wh |
| Two phones | 15W × 2 hours × 2 | 60Wh |
| Two LED lights | 10W × 5 hours × 2 | 100Wh |
| Laptop | 65W × 3 hours | 195Wh |
This example totals 733Wh per day. Replace every figure with the label, manual or measured consumption for your own equipment.
Step 2: account for the trip and useful solar
Multiply the daily load by the number of camping days. Solar can reduce the stored energy you need, but it should not be credited at its full panel rating. CampWatt uses 75% of panel watts as a planning allowance and only credits solar between camping days.
For a two-day trip with a 200W panel and 4.5 effective sun-hours, the planning harvest is approximately 200 × 4.5 × 0.75 = 675Wh per useful solar day.
Step 3: preserve a reserve
Do not plan to arrive at exactly zero. A reserve allows for hotter fridge conditions, clouds, longer device use and ageing. CampWatt starts with a configurable 20% reserve and 90% system efficiency. You can change both values in the calculator.
A light device-only camp may fit below 500Wh. A fridge-based weekend commonly moves into roughly 700–1,200Wh. Longer family trips or larger loads can move above 1,200Wh. These are starting bands—not substitutes for calculating your actual load.
Step 4: check running watts and startup surge
Find the continuous output rating of the exact model. Then check the largest appliance startup load, particularly for compressors, pumps and some 240V devices. The power station must support the output and the connector you intend to use.
A practical buying checklist
- Capacity at or above your calculated Wh target
- Continuous output above your largest working load
- Enough startup surge for compressor or motor loads
- Solar voltage and current compatible with your panel
- Suitable 12V, USB and Australian 230V connections
- Weight, warranty and local support you are comfortable with
Planning information only. Confirm product specifications, connector compatibility and manufacturer safety instructions before purchase or use. Work on 230V electrical systems should be performed only by appropriately licensed people.