What a small 300 watt power station can and cannot run in a blackout: phones, lights, a CPAP, a router and a fridge for short stretches.
- A small unit shines with phones, lights, a router and a CPAP.
- Anything that heats, such as kettles and heaters, is out of reach.
- Check watts and watt-hours, then add a reserve.
Small power stations are popular because they are light, quiet and affordable compared with big units. But a small battery has honest limits. Before you rely on one, it helps to understand what the numbers on the box mean and what a unit in the 300 watt class can reasonably do.
Two numbers to know
A power station has an output rating in watts, which is how much it can supply at once, and a capacity in watt-hours, which is how much energy is stored. A "300 watt" unit can power devices that together draw up to about 300 watts. How long it lasts depends on its watt-hour capacity, which varies by model, so check the specs. Learn the basics in how to calculate watt hours.
Actual runtime is less than capacity divided by load, because the inverter and other parts waste some energy. Plan on a reduced figure, and keep a reserve.
What a small unit does well
- Phones and tablets: Many full charges from a single battery.
- LED lights: Hours and hours of light from a few bulbs.
- Wi-Fi router and modem: Small steady loads that can run for many hours.
- Laptop: Several charges, depending on model.
- Radio and fans: Low draw, long runtime.
What it can do with limits
CPAP: Many CPAP machines use little power, especially without the heated humidifier, so a small battery may cover a night or more. Check your device's label and see how long a power station will run a CPAP. For any medical device, talk to your provider and read CPAP and medical devices in a power outage.
Fridge: A modern fridge may draw modest running watts but needs a start-up surge. A small station can sometimes keep one going for a few hours, not days. See how long a power station runs a fridge. A better plan is to keep the doors closed and use the battery for short cooling periods.
TV: A small TV and a router together draw little. See TV and router runtime.
What it cannot run
- Space heaters, electric kettles, hair dryers, toasters and microwaves. They draw more than a 300 watt unit can supply. Read space heaters and electric blankets and microwave or kettle.
- Furnaces, central air and electric water heaters.
- Power tools and anything with a large motor.
- A sump pump with a high start-up surge, in most cases. Check sump pump sizing.
A quick test you can do tonight
Plug in a lamp or a fan that you know the wattage of, note the battery percentage and the time, and check again after an hour. This simple test shows how fast your own unit drains, which is more reliable than any rule of thumb. Repeat with a phone charger or your router. Write the results on a card and keep it with the unit so everyone in the household knows what to expect.
Make the most of a small battery
- Charge it fully before storms and keep it topped up.
- Plug in only what you need, and use the DC or USB ports when possible, since they are more efficient than the AC outlets.
- Use LED lights and headlamps rather than a lamp. See headlamps and lanterns.
- Run loads in short windows rather than all day.
- Turn the unit off when nothing is plugged in.
- Add a solar panel if you expect long outages. See charging with solar panels.
When you need bigger
If you want to run a fridge for a full day, keep medical equipment on without worry, or run several things together, you probably need a larger capacity. Use what size power station do I need and the outage planner. Then compare options in the power station hub.
Quick answers
How long will a 300 watt power station run a fridge?
Only a few hours at best, and it depends on the capacity and the fridge's surge. A small unit is not a good fit for a multi-day fridge plan.
Can a small power station run a CPAP all night?
Often yes, especially without the heated humidifier, but check your device label and talk to your provider.
What does 300 watts actually mean?
It is the most the unit can supply at one time. How long it runs depends on its watt-hour capacity.