How to size a portable power station: Wh, W and surge, with worked maths

Pinned models: EcoFlow DELTA 3 Plus (US), Jackery Explorer 1000 v2 (US), Anker SOLIX C1000 (US) · Last checked 2026-10-25

Affiliate links. Disclosure

Checked: 2026-10-25.

A power station has three numbers that matter for sizing: capacity in watt-hours (Wh), continuous AC output in watts (W) and surge (peak) output in W. Get all three right and the unit will start your loads and run them long enough.

The three numbers

Pinned example models (from manufacturer pages, checked 2026-10-25):

ModelCapacityContinuous ACSurge / peakSource
EcoFlow DELTA 3 Plus1024 Wh1800 W (2200 W with X-Boost)3600 Whttps://us.ecoflow.com/products/delta-3-plus-portable-power-station
Jackery Explorer 1000 v21070 Wh1500 W3000 Whttps://www.jackery.com/products/jackery-explorer-1000-v2
Anker SOLIX C10001056 Wh1800 W2400 W ("AC Surge Output"; delivered via SurgePad, see Step 5)https://www.ankersolix.com/products/c1000

Step 1: list your loads

Read the watts from each appliance's label or manual. The numbers below are made-up examples to show the maths, not measurements; replace them with your own.

Example loadRunning W (example)Hours per day (example)Wh per day
Wi-Fi router1224288
Laptop605300
LED lamp10660
Total82 W at once648 Wh

Step 2: allow for conversion losses

A power station's AC inverter is not 100% efficient, so you get less than the rated Wh at the outlet. None of the three manufacturers publishes an AC inverter efficiency figure on the spec pages, user guides or FAQ pages we checked (2026-10-25). For planning, this guide uses an assumed 85%; treat it as our assumption, not a manufacturer spec.

Usable Wh ≈ rated Wh × 0.85

Step 3: runtime

Runtime (hours) ≈ usable Wh ÷ load W

For the 82 W example load on a DELTA 3 Plus: 870 ÷ 82 ≈ 10.6 hours. The daily 648 Wh fits in about 870 Wh with roughly 220 Wh spare.

Worked check for a single 100 W load on each pinned unit:

Step 4: check continuous watts

Add up everything that might run at the same moment. That total must stay below the continuous AC rating. An example 1500 W kettle plus an example 300 W load (1800 W together) would exceed the Explorer 1000 v2's 1500 W rating but sit at the DELTA 3 Plus and SOLIX C1000's 1800 W limit, which leaves no headroom. We found no manufacturer figure for how much headroom to leave, so this guide does not recommend a specific margin.

Step 5: check surge

Motors can draw several times their running watts for a moment at start-up. The appliance manual or label sometimes lists a starting or locked-rotor figure; if it does not, ask the appliance manufacturer. This guide does not use a generic start-up multiplier because we found no official one. The starting watts must stay below the station's surge figure.

Note on "boost" modes: EcoFlow X-Boost and Anker SurgePad let resistive loads above the rated output run at reduced power. Anker's C1000/C1000X user guide (model A1761) says SurgePad lets the unit "power high-wattage devices up to 2400W without overload", turns on when total output exceeds the rated output, does not work in bypass mode, and "does not support precision instruments and other devices that have voltage protection or strict voltage requirements". So Anker's 2400 W figure is a SurgePad limit for heat-type loads, not a motor-start surge rating; Anker does not publish a separate motor-start surge figure on the pages we checked. C1000 and C1000X share one user guide and model number (A1761).

Quick sizing worksheet

  1. Total running W of things used together = ____ W (must be below continuous rating)
  2. Largest starting W of any motor = ____ W (must be below surge)
  3. Daily Wh = sum of (W × hours) = ____ Wh
  4. Needed rated Wh ≈ daily Wh ÷ 0.85 (assumption) = ____ Wh

Affiliate placeholder: EcoFlow / Jackery / Anker SOLIX via Impact (no program active, no link)

Sources

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