Size the load before you buy. That is how you decide what size power station actually fits a fridge, a CPAP, or a router — not the watt-hours on the box.
Disclosure: This page contains affiliate links. We may earn a commission if you buy through them. Last updated: 19 September 2026.
The short version
A power station has two jobs, and they are not the same number. Watts start the appliance. Watt-hours keep it running. Buyers get this backwards because the box leads with watt-hours and the ad leads with a lifestyle photo.
Size the load in four passes:
- List every appliance that must stay on at the same time.
- Write three numbers for each one: running watts, startup (surge) watts, and how many hours or what duty cycle.
- Add running watts. Note the single largest surge. Convert hours into watt-hours.
- Pick a station whose continuous watts beat the running total, whose surge beats the largest motor start, and whose usable watt-hours beat the energy you need.
If you only remember one planning rule: treat about 85% of the sticker watt-hours as usable. Inverters lose energy as heat. Independent tests often land in the low-80% range.
Watts vs watt-hours, in one kitchen
A typical modern top-freezer refrigerator draws about 100–200 W while the compressor is on, and a short 400–800 W spike when that compressor starts. It does not draw 150 W all day. The compressor cycles. A 30–40% duty cycle is a normal planning range for a closed door in a temperate kitchen.
Energy for one day at 150 W running and 35% duty cycle:
150 W × 0.35 × 24 h = 1,260 Wh per day.
A “1,000 Wh” station is not a full day of that fridge after losses. Plan closer to:
1,000 Wh × 0.85 = 850 Wh usable → 850 ÷ (150 × 0.35) ≈ 16 hours.
That is an overnight outage for many homes. It is not a three-day storm without solar or a bigger pack.
The three numbers on every nameplate
| Number | Unit | What it decides |
|---|---|---|
| Running output | W | Can it keep the appliance on after start? |
| Surge / peak output | W | Can it start a compressor or motor? |
| Capacity | Wh | How long, after you apply the usable factor? |
Ignore marketing extras until these three clear the load.
Load cards we use on this site
Start with the appliance, not the brand. Add only what must run together.
| Load | Running W | Surge W | Duty / use | Planning note |
|---|---|---|---|---|
| Wi-Fi router + modem | 10–20 | 20–30 | Continuous | Any travel station covers this. |
| LED lights (5 bulbs) | 50 | 50 | Evening | Do not size the house from lights. |
| Laptop | 40–70 | 70 | Work block | Prefer USB-C PD when available. |
| CPAP (no humidifier) | 30–60 | 60–90 | 6–8 h night | Battery sizing only — not medical advice. |
| CPAP + humidifier | 50–90 | 90–120 | 6–8 h night | Humidifier is the tax. Size up one class. |
| Mini fridge | 50–100 | 150–300 | 30–40% | Confirm surge. |
| Top-freezer fridge | 100–200 | 400–800 | 30–40% | Need ~1,500 W-class surge headroom. |
| French-door fridge | 150–300 | 600–1,200 | 35–45% | Need 1,800 W+ and more Wh. |
| Chest freezer | 50–100 | 200–500 | 30–40% | Keep the lid shut. |
| Microwave | 800–1,200 | 1,200 | Minutes | Inverter size is the gate. |
| Sump pump 1/3 HP | 800–1,000 | 1,500–2,000+ | Intermittent | Surge kills undersized stations. |
| Window AC 5–8k BTU | 500–900 | 1,200–1,800 | High duty in heat | Often wants 2 kWh class or more. |
These ranges are planning values. Read the appliance label. If the label shows amps: watts ≈ volts × amps.
Worked example 1 — Overnight outage, apartment
Must stay on: top-freezer fridge, router, phone charging, one lamp. No microwave. No AC.
Running together when the compressor is on: 150 + 15 + 20 + 10 = 195 W. Largest surge: fridge ~600 W.
Energy overnight (14 hours), fridge at 35% duty, others continuous:
- Fridge: 150 × 0.35 × 14 ≈ 735 Wh
- Router + phones + lamp: 45 W × 14 h ≈ 630 Wh
- Total ≈ 1,365 Wh needed → 1,365 ÷ 0.85 ≈ 1,606 Wh sticker.
A 1,000 Wh class station is short for this full list. A 2,000 Wh class station clears it with margin. A 1,000 Wh class can still protect the fridge alone for roughly half a day to a day.
Inverter gate: 1,500–1,800 W continuous with 2,400 W+ surge is the comfortable band for that fridge.
Worked example 2 — CPAP night plus a router
Must stay on: CPAP without humidifier at 45 W for 8 hours, router at 12 W all night.
Energy: (45 + 12) × 8 = 456 Wh. After the 85% factor you want about 536 Wh on the sticker. Surge is modest.
A compact LiFePO4 station in the 256–300 Wh class is tight. For humidifier use or a second night without recharge, step to the 1 kWh class.
This is battery sizing, not medical advice. Follow the device maker.
Worked example 3 — Storm weekend, house fridge + freezer
Once the three nameplate numbers are clear, what size power station you need is a class decision: travel, 1 kWh, 2 kWh, or modular.
| Class | Sticker Wh | Typical continuous W | Honest job |
|---|---|---|---|
| Travel | 256–500 | 300–600 | Phones, efficient CPAP, maybe mini fridge |
| 1 kWh apartment | 1,000–1,100 | 1,500–1,800 | Overnight fridge or WFH outage |
| 2 kWh home | 2,000–2,100 | 2,200–2,600 | Fridge + lights + overnight margin |
| Modular home | 3,000–6,000+ | 3,000–6,000 | Multi-circuit backup, some 240 V models |
Inside the 1 kWh class (manufacturer specs, 2026; street prices move):
| Model | Rated Wh | AC out / surge | Weight | Use if |
|---|---|---|---|---|
| EcoFlow DELTA 3 Plus | 1,024 | 1,800 / 3,600 W | ~27 lb | Fast AC charge and expansion |
| Anker SOLIX C1000 | 1,056 | 1,800 / 2,400 W | ~26–28 lb | 1 kWh output without EcoFlow |
| Jackery Explorer 1000 v2 | 1,070 | 1,500 / 3,000 W | ~24 lb | Lighter carry, simple UI |
| EcoFlow River 3 Plus | 286 | 600 / 1,200 W | ~10 lb | Travel and small loads only |
Solar is a recharge plan, not free capacity
A “solar generator” is a power station plus a panel. The battery is still the bottle. If the outage is 14 hours of night, solar does not help until morning. Size the battery for the dark hours first.
Regional notes
- United States: most outlets are 120 V. Whole-home 240 V loads need a station that actually outputs split-phase 240 V. Federal 25D battery credit ended 31 Dec 2025 for systems placed in service after that date.
- Canada: same 120 V story plus cold-weather derate. Keep LiFePO4 indoors.
- United Kingdom and EU: 230 V local SKU. A portable station that only powers its own outlets is not a balcony battery that backfeeds a socket.
- Australia: portable stations used as appliances are legal. Units that export into house wiring are a different legal class.
What this method refuses to do
- Name a single Best Overall that ignores your fridge.
- Use sticker watt-hours as runtime.
- Treat a gas generator and a battery station as the same product.
- Tell renters to hard-wire a transfer switch.
Next step
How the numbers on this page are sourced: How we review.
Corrections: Contact.
Disclosure: Affiliate disclosure.
FAQ
How many watt-hours do I need for a refrigerator?
Plan roughly 800–1,500 Wh of sticker capacity for one overnight on a typical top-freezer, after losses. Confirm compressor surge against the station’s peak watts.
Is 1,000 Wh enough for home backup?
Enough for a short outage on a short list: fridge or CPAP or office gear — usually not all of them for 24 hours. Two-day storms want 2 kWh and up.
Do I need LiFePO4?
For a station you will keep for years and park in a house, yes. LiFePO4 is the 2026 default in the brands we cover.
Can I run 240 V household circuits from a portable station?
Only if that exact model provides 240 V split-phase and you use a safe, legal connection. Most 1 kWh stations are appliance outlets only.