Power station spec sheets aren’t lying, exactly — they’re usually just presenting numbers in whatever way makes the product look best, and it’s on you to know which number actually matters for your use case. A few specific patterns show up constantly enough that learning to spot them will save you from buying a unit that technically matches its listed specs but doesn’t actually do what you needed.
Surge watts vs. continuous watts: the big one
This is the single most common source of buyer disappointment. A unit marketed prominently as “1000W” might only sustain 500W continuously, with the 1000W figure representing a brief surge capability for startup moments only. This matters enormously for anything with a motor or compressor — a 600W coffee maker or a refrigerator compressor can need 2-3 times its running wattage just to start, so a unit that seems to have “enough watts” on paper can still fail to start the exact device you bought it for. The honest way a spec sheet should present this is with both numbers clearly labeled and separated: something like “2,200W continuous output (4,000W surge)” — if a listing only shows one number without labeling which type it is, treat that as a red flag rather than assuming the better-case interpretation.
The surge number needs a duration too — and rarely gets one
Even when a surge rating is clearly labeled, it’s usually missing a critical piece of information: how long the unit can actually sustain that surge. A unit that holds 3,000W for just 0.1 seconds before its protection circuitry cuts out is a meaningfully weaker product than one rated for 3,000W at 0.8 seconds — but both would display an identical “3,000W surge” label on the box. There’s no easy way to check this from a spec sheet alone; it’s one of the best reasons to check independent reviews that actually test startup behavior with real motor-driven appliances rather than trusting the spec sheet number in isolation.
mAh without voltage is a meaningless number
Watch for capacity claims using milliamp-hours (mAh) instead of watt-hours (Wh) — a “300,000mAh” power station sounds enormous, but mAh without a stated voltage tells you nothing usable, since watt-hours (the actual standardized measure of energy capacity) requires multiplying mAh by voltage. Established, reputable brands use Wh because it’s the only measurement that lets you meaningfully compare one unit’s true capacity against another’s. A listing that leads with a huge mAh number and buries or omits the Wh figure is worth treating with real skepticism.
Runtime claims tied to unspecified appliances
Runtime claims tied to a specific real-world appliance, like a claim about running a fridge for many hours, are close to meaningless without the missing variables: which fridge, what size, what ambient temperature, how often the door opens, what its actual compressor duty cycle looks like. Real refrigerators vary in wattage by a factor of 3 or more depending on size and age, so this kind of claim is built to sound impressive rather than to help you calculate your actual situation. Use the watts-and-Wh math from a spec sheet’s actual numbers (see our beginner’s guide to watts, Wh, and volts) rather than trusting a headline runtime claim built around an unspecified appliance.
Usable capacity is quietly smaller than rated capacity
Power stations typically lose roughly 15% of their rated capacity to inverter inefficiency and battery management overhead — a 1,000Wh-rated unit realistically delivers something closer to 850Wh of usable energy. Marketing materials almost never subtract this loss when quoting runtime estimates, which is part of why real-world performance often falls a bit short of the numbers used to sell the unit. This isn’t a defect or a deceptive practice specific to any one brand — it’s a physical reality of how inverters work — but it’s worth factoring into your own math rather than assuming you’ll get the full rated Wh in usable output.
A short checklist before you buy
Look specifically for continuous output labeled separately from surge/peak output; capacity listed in Wh, not just mAh; a stated pure sine wave inverter (not just “sine wave,” which can sometimes be used loosely); and, where possible, an independent review that actually tested starting a motor-driven appliance rather than just quoting the spec sheet. None of this requires deep technical expertise — it just requires knowing which two or three numbers on a busy spec sheet are the ones actually worth reading carefully.
FAQ
Is a higher surge-to-continuous ratio always suspicious?
Not inherently — a genuine 2x surge-to-continuous ratio is common and reasonable for handling motor startup. What’s worth questioning is when only the surge number is advertised prominently with the continuous rating buried or absent entirely.
How do I find a unit’s real surge duration if the spec sheet doesn’t list it?
Check independent reviews and owner forums for reports of actually starting real appliances (refrigerators, power tools, well pumps) rather than relying on the manufacturer’s spec sheet alone for this specific detail.
Do all brands use these same marketing tactics?
The most reputable, established brands generally label their specs clearly with both continuous and surge ratings in Wh — these particular tricks show up more often with lesser-known or budget brands trying to make specs look more impressive at a glance.
Should I ignore surge ratings entirely and just focus on continuous watts?
No — surge rating genuinely matters if you’re running anything with a motor or compressor. The point isn’t to ignore it, it’s to make sure you know which number you’re looking at and treat an unlabeled or unusually high surge figure with appropriate skepticism.
Bottom line
Spec sheets aren’t designed to deceive you outright, but they are designed to put the most flattering number in the most visible spot. Learn to separate surge from continuous watts, insist on Wh over unexplained mAh figures, and do your own runtime math from real specs rather than trusting a headline appliance claim — that’s most of what it takes to buy the right unit the first time.
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Sources externes citées
- BackupPowerHub — 7 Portable Power Station Buying Mistakes to Avoid
- CMGM — Sourcing Power Stations: The Surge Wattage Trap