It could run a 50 W load for many hours, or a 1,500 W heater for well under an hour. Runtime is battery energy divided by load.
Planning estimate using 90% usable energy: 1,000 Wh × 0.90 = 900 Wh. Not every 1 kWh product provides exactly 900 Wh.
Capacity is fixed at 1.0 kWh (1,000 Wh). Appliance wattages are representative planning values, not specifications; use your label or a plug-in meter. Startup surge, duty cycle and inverter limits are not modeled.
Constant load, 900 Wh planning energy.
| Load | Runtime | Hours + minutes |
|---|---|---|
| 10 W | 90 h | 90 h 0 min |
| 50 W | 18 h | 18 h 0 min |
| 100 W | 9 h | 9 h 0 min |
| 200 W | 4.5 h | 4 h 30 min |
| 500 W | 1.8 h | 1 h 48 min |
| 1,000 W | 0.9 h | 54 min |
| 1,500 W | 0.6 h | 36 min |
Categories, not promises. Real runtime depends on your specific devices.
Router and modem are typically small loads, so runtime can be many hours. Wi-Fi page
DOE lists a laptop around 50 W; monitors and desktops add more. Home office
Varies by screen size and technology. Check the label.
Cycles on and off, with compressor startup. Simple W÷Wh math is incomplete. Refrigerator
Device-specific; humidifier and heated tubing can raise draw. Electrical planning only. CPAP
LED loads are low; total depends on how many fixtures run.
DOE lists 750–1,100 W, so short sessions only.
Around 1,500 W for common portable units. Personal heat
Compressor startup and cycling make this a power-limit question first. Window AC
A refrigerator's compressor cycles. DOE guidance is to divide plugged-in time by three to estimate hours at maximum wattage, but real cycling varies with room temperature, door openings and age. Daily energy is usually lower than running watts × 24 hours.
It also draws a startup surge when the compressor starts. Energy (Wh) answers "how long," while inverter surge capacity answers "will it start."
DOE guidance notes a motor can draw about three times its running current in the first second of starting. A battery with plenty of energy can still fail to start the load if its inverter cannot supply that surge. Always check the battery's continuous and surge ratings against the appliance's startup needs.
Resistance heat has no duty-cycle trick when the element is on, and the inverter must supply 1,500 W continuously.
1,000 Wh of energy. Power determines how fast you spend it.
Stored energy. How much you have. A 1 kWh battery stores about 1,000 Wh nominal.
Power. How fast you use it. A 1,500 W load is 1.5 kW. Running 1 kW for one hour uses 1 kWh.
Products differ, so use the manufacturer's rated usable or AC output energy where available.
A battery may hold enough energy for an appliance while its inverter cannot support the appliance's continuous or surge power. A 1 kWh battery with a 600 W inverter cannot run a 1,500 W heater at all, regardless of stored energy. Compare appliance watts to the product's continuous and surge ratings.
If load is zero or invalid, the calculator shows no runtime instead of dividing by zero.
It depends on the load. Using a simplified planning figure of 900 Wh (90% of 1,000 Wh), runtime in hours is 900 divided by the load in watts: 18 hours at 50 W, 9 hours at 100 W, 1.8 hours at 500 W and 0.6 hours (36 minutes) at 1,500 W.
Sometimes, depending on the refrigerator's real average draw and the inverter's ability to handle compressor startup. Refrigerators cycle on and off, so nameplate watts times clock time overstates energy use. Measure your unit with a plug-in watt meter for a real daily figure.
Briefly. A 1,500 W heater would use about 900 Wh of planning energy in roughly 36 minutes, and the inverter must also support 1,500 W continuous output.
Often possible for the electrical load alone, because many CPAP devices draw tens of watts, but heated humidifiers can draw much more. Check your device label and test runtime. This is electrical planning only, not medical advice.
No. A kilowatt-hour (kWh) measures stored or consumed energy. A kilowatt (kW) measures power, the rate of use. A 1 kW load running for one hour uses 1 kWh.
It varies by product. Inverter losses, battery management limits, temperature, load and reserve all affect it. Zaron uses 90% only as a planning assumption; check the manufacturer's specifications.