How to read this page
Energy and power are different things. A station's capacity in watt-hours decides how long it can run something. Its output in watts decides whether it can run it at all. Runtimes below use the standard planning rule:
Runtime (hours) ≈ capacity (Wh) × 0.85 ÷ device wattsRuntime by capacity
Device watts are mid-range typicals, so check your own labels. Compressor appliances (refrigerators, portable fridges) cycle on and off, so real elapsed time is usually longer than the running time shown.
| Device (assumed running watts) | 300 Wh | 500 Wh | 1,000 Wh | 2,000 Wh |
|---|---|---|---|---|
| Smartphone charging (10 W) | 25.5 h | 42.5 h | 85 h | 170 h |
| LED lights (10 W) | 25.5 h | 42.5 h | 85 h | 170 h |
| Laptop (60 W) | 4.2 h | 7.1 h | 14.2 h | 28.3 h |
| Portable fridge (60 W running) | 4.2 h | 7.1 h | 14.2 h | 28.3 h |
| CPAP machine (45 W) | 5.7 h | 9.4 h | 18.9 h | 37.8 h |
| TV (100 W) | 2.5 h | 4.2 h | 8.5 h | 17 h |
| Household refrigerator (120 W running) | 2.1 h | 3.5 h | 7.1 h | 14.2 h |
| Coffee maker (1,200 W) | 13 min | 21 min | 42 min | 85 min |
| Microwave (1,400 W) | 11 min | 18 min | 36 min | 73 min |
The two big-wattage rows also need a station whose output rating covers them. A 300 Wh unit with a 300 W output cannot run a 1,200 W coffee maker, however full its battery is.
Output rating guide
| Station output | Typically comfortable with |
|---|---|
| 100–300 W | Phones, tablets, laptops, LED lights, small fans |
| 300–700 W | The above plus portable fridges, a TV, a CPAP machine |
| 1,000–1,500 W | The above plus a household fridge (check surge), small power tools |
| 2,000 W and up | Coffee makers, microwaves and other heating loads, for short periods |
These are guidelines. Always compare the station's continuous and surge ratings with the device's running and start-up watts.
Things that surprise people
- Standby loads add up. A router, a charger left plugged in or a TV on standby draws a little around the clock.
- Cold weather shortens runtime. Batteries deliver less in the cold, and some stations limit charging below freezing. Check the operating range in your manual.
- Heated humidifiers raise CPAP draw. The 30–60 W range applies without a heated humidifier; with one, plan for more. Do not rely on a portable station as the only power source for life-critical medical equipment.
- Efficiency is lower at very light loads. A big inverter powering a tiny load wastes proportionally more energy, so use DC or USB outputs for small devices where you can.
Next step
Use the size calculator with your own devices, then read the buying guide to turn the result into a short list.