Free browser tool
Power station energy planner
Enter the capacity in Wh, or in Ah or mAh with the nominal voltage, the conversion efficiency and any reserve you keep back, then list your devices with their watts and hours of use. See whether the usable energy covers them and how much is left over or missing. Other modes estimate the runtime of a mix of loads, or follow charging energy you enter, for example from a solar panel, against what you use.
Runs on this device. No upload, account or tracking.
Your battery and devices
List what you will run and for how many hours within the planning period. With a capacity, the planner says whether the usable energy covers it; without one, how much capacity it needs.
The nominal capacity from the label or manual. In the budget mode, leave it blank to see the capacity your devices need.
Wh = Ah × V, or mAh × V ÷ 1,000. Use the nominal voltage printed on the battery.
Your inverter or converter's efficiency, from the manual or your own estimate: above 0 and up to 100%. No efficiency is assumed for you.
Share of the nominal capacity you never want to use, from 0 to below 100%.
A constant extra draw, such as an inverter's idle power, for the whole period: at the output it passes through the efficiency, from the battery it does not.
Up to 87,600 hours. Each device's hours of use must fit within it.
Shows the nominal capacity needed to run the loads this long, up to 87,600 hours.
Energy in the battery before the first interval, at most its capacity.
Share of the charging energy that ends up stored, above 0 and up to 100%.
Share of the stored energy that reaches your devices, above 0 and up to 100%.
Devices
Power in watts while on, and hours of use within the planning period. Blank rows are ignored.
Intervals, in order
For each interval: its length in hours, the charging energy coming in (Wh, for example a solar panel's output you estimate) and the energy your devices use (Wh). Charging is counted before use within an interval. Blank rows are ignored.
Advanced: the whole input as JSON, alternatives and duty ranges
Edit to calculate from this JSON instead of the form. Fractions are written from 0 to 1 here (0.85, not 85). In the runtime mode you can add "alternatives": [{"name": …, "capacity": {"value": …, "unit": "Wh"}}] to compare up to 20 capacities, and a "duty_range" with active_w, idle_w, min_fraction and max_fraction. Editing the form again rewrites the JSON and keeps the alternatives and the duty range.
Budget: up to 100 devices over a planning period of up to 87,600 hours. Runtime: up to 100 loads whose shares of the time add up to exactly 100%, a target of up to 87,600 hours and 20 alternative capacities (Advanced JSON). Recharge: up to 1,000 intervals of up to 8,760 hours each and 8,760 hours in all. Capacity, watts and Wh up to 1,000,000,000,000 and nominal voltage up to 1,000,000 V, with at most nine decimal places; names of 1 to 200 characters; up to 100 KB of input and a 1 MB report. Energy only: device ratings, surge power, sockets, temperature, aging, cutoff and charging curves are not checked.
Result
Result
Technical output
The download contains the same JSON: the engine's exact decimals, its formula and limitations, and your inputs.
About this tool
What this tool does
Plan the energy of a portable power station, solar battery or power bank in your browser: check whether its usable capacity covers your devices over a period, estimate how many hours it runs a mix of loads, or follow charging and use interval by interval, with a reserve and conversion efficiency you choose.
Limits and safe use
Budget: up to 100 devices over a planning period of up to 87,600 hours. Runtime: up to 100 loads whose shares of the time add up to exactly 100%, a target of up to 87,600 hours and 20 alternative capacities (Advanced JSON). Recharge: up to 1,000 intervals of up to 8,760 hours each and 8,760 hours in all. Capacity, watts and Wh up to 1,000,000,000,000 and nominal voltage up to 1,000,000 V, with at most nine decimal places; names of 1 to 200 characters; up to 100 KB of input and a 1 MB report. Energy only: device ratings, surge power, sockets, temperature, aging, cutoff and charging curves are not checked. Use the capacity, efficiency and power figures of your own devices, and leave a margin. The result is an energy estimate from your numbers, not a guarantee of runtime, a check that a device can be plugged in or started, or safety advice, and nothing is sent to a server or a model.