Power station buyer's guide
A portable power station is a battery, an inverter and a set of outlets in one box. Choosing one comes down to four questions, in this order: how much energy you need, how much power at once, how fast it has to refill, and how you'll carry it. Everything else is a tiebreaker.
1. Capacity: how much energy, in watt-hours
Write down what you'll run and for how long. Multiply watts by hours for each item, add them up, then divide by 0.85 to cover inverter losses. That is the rated capacity you need.
- Phone (5 W) charged 10 times: about 150 Wh
- Laptop (50 W) for 8 hours: 400 Wh
- CPAP without humidifier (30 W) for 8 hours: 240 Wh; with heated humidifier, closer to 600 Wh
- Compact 12 V fridge (45 W average) for 24 hours: about 1,100 Wh
- Full-size refrigerator (150 W average) for 24 hours: about 3,600 Wh
That math is why the size classes exist: a weekend of phones and lights lives in the small class, a fridge through an outage needs large, and whole-home backup is extra large.
2. Output: how much power at once, in watts
The inverter's continuous rating must exceed the biggest load you'll run at the same time. Motors (fridge compressors, pumps, power tools) draw two to three times their running wattage for a second at startup; the surge rating covers that. A 1,800 W inverter runs almost any single household appliance; 300 W runs electronics only. Some brands advertise a boosted figure that only works by lowering voltage; it's fine for resistive loads like heaters and kettles and not for motors or electronics.
3. Recharge speed
Most modern units refill from the wall in one to two hours. Older designs with external power bricks can take eight or more. If you'll use the unit for outages, fast AC charging matters: an hour of grid power between failures refills a fast unit completely. Solar input is the other side of this; see solar input explained.
4. Weight
Lithium iron phosphate cells, which you want for longevity, are heavier than the older chemistry. A 1 kWh unit weighs 25 to 30 pounds; 2 kWh, 45 to 60; anything over 3 kWh is a two-person lift or comes on wheels. If you'll move it often, check watt-hours per pound on each model page.
Tiebreakers
- Chemistry: insist on LiFePO4 for anything you'll cycle regularly. See LiFePO4 vs NMC.
- UPS switchover: only matters if a computer or network gear will stay plugged in. See UPS explained.
- Expandability: cheaper than a second unit only in some cases. See expandable batteries.
- Ports: at least one 100 W USB-C port saves carrying laptop bricks.
- App: convenient, rarely essential.
What to ignore
Peak or surge wattage as a headline number; "lifetime" cycle claims without a capacity threshold; included cables and lights; claims of running a house for days, which depend entirely on what's in the house. Rated capacity is also a marketing number: see rated vs usable capacity.
Price
Expect roughly $400 to $700 per kilowatt-hour of capacity at street prices. Below that range the unit usually has an older chemistry or a weak inverter; well above it you're paying for a brand, a feature or a premium shell. The value lists sort on exactly this.