Estimate runtime before you buy more battery
A useful runtime estimate starts with energy, not a marketing label. Enter battery capacity, choose the loads you actually expect to support and use the result as a planning estimate—not a guarantee for a specific appliance or medical device.
Power Station Runtime Calculator
Choose a battery size and the devices you actually want to support. The calculator converts that use pattern into one understandable runtime estimate.
I know my own device consumption
Add custom loads using running watts and expected hours of use per day.
What this tool is helping you decide
Power stations are commonly described by watt-hours, while appliances are described by watts. Runtime depends on both the stored energy and how much energy your selected loads use over time. Refrigerators cycle, routers may run continuously and medical devices can change consumption depending on settings and accessories.
How the estimate works
PrepMorrow estimates usable battery energy from the rated watt-hour capacity and your selected efficiency assumption. It then compares that usable energy with a daily-use profile for the selected loads. The separate simultaneous-load figure helps you notice when inverter output may matter even if total battery capacity looks adequate.
Where the result can be wrong
Real runtime changes with inverter losses, battery management, temperature, battery age, appliance cycling and startup surge. Preset profiles are planning examples. For CPAP or other powered medical equipment, use the actual device specification and manufacturer or healthcare guidance.
Questions people ask about this tool
Why is usable energy lower than the battery label?
Conversion losses and battery-management limits mean not every rated watt-hour reaches an AC appliance.
Why does the refrigerator profile use daily energy?
A refrigerator compressor cycles on and off, so multiplying running watts by 24 hours can badly overstate normal daily use.
Is runtime the same as inverter compatibility?
No. A battery can contain enough energy but still have too little continuous or surge output for a load.
Can I use this for a CPAP?
Use it only as a planning aid after replacing the preset with the actual device consumption. Heated humidifiers and other settings can materially change use.