01 / Portable battery planning

Size your power station.
Plan your runtime.

Plan a camping setup or a small backup load. Add your appliances, allow for losses, and check the battery capacity and output ratings you need.

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Build your power plan

Example appliance ratings, not tested specifications. Edit every value to match your equipment.

Connected hours × duty cycle = operating hours. Set duty to 100% when watts is already an average reading. Startup watts are per appliance, not a universal multiplier.

Allow for real-world losses

Planning period (hours)

Conversion efficiency (%)

Illustrative, excludes the separate standby draw.

Battery capacity held in reserve (%)

Station standby draw (W)

Assumed active throughout the planning period.

Check a battery you are considering

Advertised battery capacity (Wh)

Continuous output rating (W)

Surge output rating (W)

Enter real specifications from the manufacturer. This calculator does not certify product compatibility.

The calculation, not a black box

For each appliance, multiply running watts by quantity, connected hours and duty cycle. Conversion losses apply to the appliance energy; standby consumption is added separately.

Load Wh = Σ(watts × quantity × hours × duty)
Battery draw = load Wh ÷ efficiency + standby W × planning hours
Required Wh = battery draw ÷ (1 − reserve)

Runtime repeats the same average usage profile. It is not a prediction of when an individual fridge will stop. Continuous output assumes all active appliances can run together; the first surge estimate starts one appliance while the others run.

Reference: OUPES: runtime formula and real-world limitations.

Guide: measuring a fridge’s battery needs →

Before you rely on the result

Are the appliance presets accurate for my equipment?

No. They are labelled examples. Measure your own usage over a representative period. A compressor fridge’s nameplate running watts is not its 24-hour average.

Does enough Wh mean it can run everything?

No. Check inverter watts, startup surge magnitude and duration, voltage, connector type, low-load cutoff and the manufacturer’s operating instructions.

Does this include solar charging or medical backup?

No solar input is credited. Do not use this tool as a medical-device, life-support or home electrical-installation design. Those require manufacturer guidance and appropriate specialist checks.