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How long will a power station run your appliances?

By WhatStaysOn · Updated October 12, 2026

Step 1: find the average load

Add up what each appliance draws on average, not its peak. Most electronics draw steadily, but some cycle on and off:

• Steady loads: a router (about 10W), LED bulbs (about 9–10W each for an 800-lumen bulb, per the FTC), a TV, a fan, a CPAP.
• Cycling loads: a fridge or freezer compressor runs only part of the time. Multiply its running watts by the share of time it runs — the duty cycle. A 150W fridge running 40% of the time averages 60W. A laptop or phone charger also varies; we assume 60% and 50%.

Where to find watts: the appliance label or power adapter (watts, or volts × amps), the manual, or a plug-in watt meter — the most accurate option. For fridges and freezers, the yellow EnergyGuide label’s yearly kWh ÷ 8.76 gives average watts directly.

Step 2: work out usable energy

The number on the box (Wh) is the battery’s rated capacity. Less than that reaches your appliances:

• Conversion losses. AC outlets run through an inverter that turns battery DC into household AC. Some energy becomes heat.
• The inverter’s own draw. The inverter uses power just to stay switched on, whatever you plug in. At big loads this barely matters; at small loads it dominates.
• Reserve. You shouldn’t plan on the last few percent — batteries age, cold reduces capacity, and you want something left for a phone at the end. We keep 10% back by default.

Independent tests show the effect of load size clearly. Outdoor Life measured stations delivering 76–92% of rated capacity at a 380W load, but only 49–77% at about 34W. OutdoorGearLab measured a Jackery Explorer 1000 v2 delivering 910Wh from its 1,070Wh battery (about 85%) in a full discharge test.

So instead of a fixed efficiency, the planner estimates it from your load: about 90% conversion efficiency plus 12W of inverter overhead. That gives about 68% at 34W, 78% at 70W and 88% at 380W — within those measured ranges. Some stations do worse: Outdoor Life’s figures for the BLUETTI AC180 at about 34W were 40–54%. It’s an estimate; the range shown under each result covers 88–92% conversion and 6–25W of overhead.

The practical lesson: for small loads, use the station’s DC or USB-C ports where your device allows it. A router on a 12V adapter, or phones on USB-C, skip the inverter entirely.

Step 3: put it together — a worked example

Fridge plus Wi-Fi router overnight, 8 hours, on a 1,024Wh station:

1. Average load: fridge 150W × 40% = 60W, plus router 10W = 70W.
2. Energy needed: 70W × 8h = 560Wh.
3. Efficiency at 70W: 70 ÷ (70 ÷ 0.90 + 12) ≈ 78%.
4. Usable energy: 1,024 × 0.78 × 0.90 ≈ 719Wh.
5. Runtime: 719 ÷ 70 ≈ 10.3 hours — it covers the night.
6. Battery size to look for: 560 ÷ (0.78 × 0.90) ≈ 798Wh.

Two more checks before calling it a match. Everything running at once (150W + 10W = 160W) must be under the station’s continuous rating. And the largest start-up spike — the fridge’s, which we estimate at 800W, plus the router’s 10W — must be under its surge rating. The planner runs all three checks together, using the same numbers, so the battery size, the verdict and the runtime always agree.

Three mistakes behind most wrong runtime claims

1. Dividing the box capacity by the load. 1,024Wh ÷ 70W = 14.6 hours sounds great, but ignores conversion losses, inverter overhead and reserve. Real runtime is about 30% shorter.
2. Using a fridge’s running watts all night. 150W × 8h = 1,200Wh overstates the need by more than double, because the compressor isn’t running most of the time.
3. Treating a boost mode as surge. X-Boost, Power Lifting and similar modes run heating appliances at reduced power. They don’t help a compressor start. Use the surge (peak) rating.

What else shortens real runtime

• Cold. Lithium batteries deliver less in the cold, and most stations won’t charge below freezing (32°F).
• Age. Capacity falls slowly with use; the cycle-life claims on our station pages show how makers rate it.
• Hot rooms and open fridge doors. Both make the compressor run more.

The planner does all of this for your appliances, shows the time of night each station runs out, and lists exactly which check a station fails. The full formulas are on How we calculate. When the outage runs long, the other half of the plan is putting energy back: see how to recharge a power station — wall, solar, car and generator charging, with times for every station we cover.

Sources

• Outdoor Life: best portable power stations (Jan 2026) — delivered energy measured at ~34W and ~380W loads
• OutdoorGearLab: Jackery Explorer 1000 v2 review — measured 910Wh delivered from a 1,070Wh battery
• Virginia Cooperative Extension: estimating appliance energy use — duty-cycle method for cycling appliances
• FTC: LED bulbs and lumens — an 800-lumen LED uses about 9W