Quick-pick disclosure: As an Amazon Associate, Saturday Gear Co. earns from qualifying purchases at no extra cost to you. Recommendations below distinguish firsthand ownership from research-based picks.
Two battery sizes to compare
EcoFlow DELTA 3 Plus
EcoFlow lists 1,024 Wh capacity and 1,800 W AC output for this model. It is the more portable, lower-capacity choice for modest loads. Compare your measured running and startup requirements; neither figure guarantees a particular runtime. We do not own it.
Check current options on AmazonAffiliate link. Check the exact model, current specifications and price before ordering.
EcoFlow DELTA 2 Max
EcoFlow lists 2,048 Wh capacity and 2,400 W AC output. Choose the larger battery only when your energy budget and load justify it; actual AC runtime is lower than nameplate watt-hours because of conversion losses and variable loads. We do not own it.
Check current options on AmazonAffiliate link. Check the exact model, current specifications and price before ordering.
For a refrigerator, follow the calculation in our overnight refrigerator guide. For longer outages, compare the generator sizing guide.
Three numbers actually matter
Portable power stations are easier to compare once you separate three specifications: continuous AC output in watts, short-duration surge output, and battery capacity in watt-hours. A large battery does not automatically mean a station can run a high-draw appliance; the inverter still has to supply enough instantaneous power.
| Specification | What it tells you | Why it matters |
|---|---|---|
| Continuous watts | How much load the inverter can supply | Determines what can run simultaneously |
| Surge watts | Short burst capability | Helps start motors and compressors |
| Watt-hours (Wh) | Stored battery energy | Helps estimate runtime |
Step 1: total your running watts
List the devices you intend to operate simultaneously and add their running wattage. A 60-watt television, 45-watt fan and 100-watt electronics load, for example, create a roughly 205-watt running load. Manufacturer labels and manuals are better sources than generic internet estimates because seemingly similar appliances can draw very different amounts of power.
Do not size the inverter right at the calculated load. Extra capacity gives you room for unexpected loads, conversion losses and future equipment.
Step 2: account for startup surge
Motors and compressors can briefly require considerably more power at startup than while running. Refrigerators, pumps, air compressors and some tools are common examples. Check the equipment manufacturer’s starting requirement and make sure the station’s surge rating can accommodate it.
If your backup plan includes larger motor loads, our generator sizing guide explains the same running-versus-starting-watts problem for fuel-powered generators.
Step 3: estimate battery runtime
A rough starting calculation is battery watt-hours ÷ average load watts = theoretical hours. So a 1,000Wh battery supporting a steady 200-watt load has a theoretical runtime of about five hours.
Real runtime will be lower. Inverter conversion losses, battery-management overhead, temperature, battery age and the efficiency of the connected equipment all consume some of the advertised capacity. Use the simple calculation for planning, then leave a reserve rather than expecting every advertised watt-hour to reach your devices.
Estimate power-station runtime
Enter the station’s rated battery capacity and your estimated average load. The planning factor is adjustable because actual delivered energy varies by inverter, device, temperature and battery condition.
This is an estimate for a steady load. Startup surge must also fit the inverter rating. For critical devices, check actual draw and keep a backup plan.
What size makes sense for the job?
Phones, cameras and light tailgating: Smaller stations are easier to carry and may be all you need when the load is primarily USB devices, lights and modest electronics.
Camping: Add every overnight load you actually expect to use. Fans, lights, portable refrigerators, CPAP equipment and cooking appliances can change the calculation quickly. Heating elements such as kettles, hot plates and coffee makers often demand much more inverter output than small electronics.
Emergency essentials: Build the load list around what truly needs to stay powered: refrigeration, communications, lighting and selected medical or household equipment. If the goal expands toward multiple large appliances or extended outage coverage, compare a power station against a properly sized generator rather than simply buying the largest battery you can find.
Charging speed matters too
Capacity tells only half the off-grid story. A large battery that takes a long time to recharge may be a poor fit for repeated daily use. Check AC charging time and, if you plan to use solar panels, the station’s supported solar input voltage and wattage. Solar production varies with weather, panel angle and available sunlight, so the panel’s headline rating should not be treated as guaranteed continuous input.
Common sizing mistakes
Buying solely by watt-hours is the biggest one. Other mistakes include ignoring startup surge, assuming advertised capacity is fully usable, overlooking high-draw heating appliances, and calculating each device separately instead of considering which ones will run at the same time.
For a broader weekend setup, pair the power calculation with our cooler sizing guide. For home outage planning involving larger loads, start with the generator guide. For one common essential load, see our refrigerator overnight backup guide.
How we built this guide
This is a sizing and planning guide, not a claim that every power station on the market was hands-on tested. We focus on the specifications that determine whether a station fits the job, and we distinguish researched guidance from hands-on experience. See our editorial policy for how Saturday Gear Co. evaluates gear and handles corrections.
Bottom line
Start with the load, not the battery. Determine simultaneous running watts, the largest startup surge and how many hours you need the equipment to operate. Then choose a power station whose inverter and battery both exceed those requirements with sensible headroom. That produces a much better purchase than shopping by battery capacity alone.
← Back to Weekend Gear · All Guides · How we evaluate gear · Affiliate disclosure
Power-station buying shortlist
These are use-case recommendations based on the buying criteria above, not hands-on product tests. Check the current manufacturer specifications and the exact model before ordering.
Small portable unit
For phones, lights and small electronics, add your actual wattages and hours first. Compare USB outputs, AC inverter output and carrying weight.
Watch out: Do not assume it will power a refrigerator.
Mid-size battery for overnight essentials
For a fan, CPAP or portable fridge, confirm each device’s input, startup draw where relevant and an overnight energy budget. Compare usable capacity and recharge time.
Watch out: Test the intended equipment and keep a backup plan for medical needs.
Expandable unit for extended backup
For larger essential-load plans, compare continuous and surge output, expansion cost, solar-input limits and warranty support.
Watch out: A large battery still needs a reliable recharge source.
Affiliate disclosure: As an Amazon Associate, Saturday Gear Co. earns from qualifying purchases. We may earn a commission through the product links on this page at no extra cost to you. Full disclosure.
For longer fuel-powered backup, compare gasoline and propane generator output.