Power Bank, Portable Power Station or Generator: Which One?
How to work out how much power you need in an outage (watts and watt-hours) and what fits best: power bank, portable power station, solar panel or generator.
Before you buy anything, there's a question almost nobody asks that decides everything: what do I need to keep running, and for how long? A phone and a light don't ask for the same thing as a refrigerator. Do the math first, pick the gadget second.
Two units, that's all
Watts (W) say how much power a device draws at a given moment. Watt-hours (Wh) say how much energy it uses over time, and they're the ones that tell you how long a battery lasts. The U.S. Department of Energy sums it up as watts times hours of use. A 10 W device running for 5 hours uses 50 Wh.
The wattage printed on a label is the maximum the device can draw. Motors (like a refrigerator's) draw considerably more when they start than when they're running.
Approximate values, to give you a feel:
| Device | Typical power | One night (10 h) |
|---|---|---|
| LED light | 5 to 10 W | 50 to 100 Wh |
| Wi-Fi router | 10 to 15 W | 100 to 150 Wh |
| Small fan | 20 to 50 W | 200 to 500 Wh |
| Laptop | 30 to 65 W | depends on hours of use |
| Phone (one full charge) | n/a | about 10 to 20 Wh total |
These are rough ranges: measure yours with the label or a cheap plug-in meter.
Power bank: the simple one
Good for phones, rechargeable flashlights and not much else. Capacity is listed in mAh. To convert to Wh, multiply by 3.7 and divide by 1,000: a 10,000 mAh power bank holds about 37 Wh nominal, and in practice delivers somewhat less. That's enough for two or three phone charges. It's cheap, fits in a 72-hour kit and you have to keep it charged.
Portable power station: a big battery with outlets
It's a battery with an inverter, and capacities usually range from a few hundred to over two thousand Wh. It can run a router, lights, a laptop and, depending on the model, a small appliance. It gives off no combustion fumes and makes little noise, so it's the safest choice indoors. What to look at: capacity in Wh (how long it lasts) and maximum output in W (what it can drive). If you add up your devices and add a 25% margin, you have the size you need.
Solar panel: to recharge, not to run
A portable 100 W panel, in the best case and with about four hours of strong sun, delivers roughly 400 Wh in theory. In practice it will be less: clouds, sun angle and losses. It's a way to extend a power station, not replace it. It matters if the outage lasts days.
Gasoline generator: power, with one condition
It runs big loads, but it produces carbon monoxide, a gas with no smell or color that kills without warning. The rules come from health and safety agencies:
- Use it outdoors only, more than 20 feet (6 meters) from doors, windows and vents, with the exhaust pointed away from the house.
- Never in the house, garage, basement or shed, not even with the doors open.
- Keep battery-powered carbon monoxide detectors.
- Don't plug it into a wall outlet: that takes a transfer switch installed by an electrician.
- Turn it off and let it cool before refueling.
Which one fits you?
- Only phones and a light: a power bank and rechargeable flashlights.
- Router, laptop, lights, maybe a fan: a portable power station, plus a panel if the outage could be long.
- Big loads for days: a generator, with everything above on safety.
- Medical equipment that depends on power: make a plan with your doctor. Don't rely on a household battery alone.
And remember that a flashlight is safer than a candle. To round out the picture, see how to protect the food in your refrigerator during an outage and what else belongs in your 72-hour kit.
Write it down so you don't improvise
Log your batteries, flashlights and power banks in Despendo's pantry with a check date, and add them to your plan so the list of things that depend on electricity is written down before you need it.
Sources and further reading
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