Surge vs Continuous Wattage
Every power station lists two wattage numbers, and confusing them is one of the most common — and most consequential — mistakes when sizing a unit for motor-driven appliances like fridges, pumps, or power tools.
Two different questions, two different numbers
ac_output_w (continuous) answers: 'how much power can this supply while something is already running?' Exceed this and the unit can't sustain the load — it'll shut off or fault.
surge_output_w answers a completely different question: 'how much power can this briefly supply the instant a motor starts?' Motors draw far more current to overcome initial inertia than they do once spinning, and that spike typically lasts only a second or two.
Why a unit can fail even with plenty of continuous wattage
This is the trap: a power station can have generous continuous output — say 2,000W — and still fail to start a well pump that only draws 900W running, if its surge rating is too low to cover that pump's 3,000W+ startup spike. The motor never even gets going, regardless of how much sustained power the unit could theoretically supply once it was running.
This is exactly why this project's well-pump use-case weights surge_headroom at 40%, the highest weight of any factor across all 9 use-cases here — for a motor-driven appliance, surge isn't a secondary spec, it's the gatekeeper.
A wrinkle: 'boost' and 'lifting' modes aren't always the same as surge
Some brands market a separate 'X-Boost,' 'Power Lifting Mode,' or similar feature that's distinct from the unit's standard surge spec — sometimes it's a genuine higher-capacity mode, sometimes it's a marketing gloss on the same underlying number. This project deliberately did not conflate these two figures when building its entity dataset — see individual entities' open_flags[] for the specific cases where this distinction was found and kept separate.
Key Facts At a Glance
- Continuous (ac_output_w) is what a device draws while running — this must never be exceeded or the unit can't sustain the load
- Surge (surge_output_w) is the brief spike when a motor starts — typically 2-5x the running wattage for pumps, compressors, and other motor-driven appliances
- A unit can have plenty of continuous wattage but still fail to start a well pump or fridge compressor if its surge rating is too low
- This is why the well-pump use-case in this project weights surge_headroom at 40% — the single highest weight of any factor across all 9 use-cases — a pump motor simply won't start without it, regardless of every other spec
- Some brands market a separate 'boost' or 'lifting power' mode distinct from the standard surge spec — this project deliberately does not conflate the two (see individual entity open_flags[] where this distinction was found)
Related
/best/power-stations/well-pump/ · /best/power-stations/mini-fridge/ · /tools/power-station-runtime-calculator/