How we research
Last updated
We do not run a test lab and we have not tested the power stations, batteries or appliances we write about. What we can do is read the evidence carefully, show the math and tell you where each number comes from. This page explains how.
The sources we use, in order of trust
- The maker’s own documents: user manuals, specification sheets and support pages. Battery capacity, AC output, surge rating, charging limits, operating temperatures and the power the inverter uses on its own come from here.
- Public bodies and standards: safety agencies, energy agencies and electrical utilities in the United States and Canada, and the safety standards a product is listed to. We use them for carbon monoxide, electrical safety, appliance energy use and medical-device outage planning.
- Independent measurements: published bench tests and university extension material, presented as what they are, with their date.
Retail listings and customer reviews are not used as evidence. When the only source for a number is the maker, we say so.
How we estimate runtime
Every runtime on this site uses the same formula, shown on the page:
usable capacity ÷ (appliance load + what the station uses on its own)
- Usable capacity. A power station cannot deliver all of its rated battery capacity as household (AC) power: some is lost in the inverter. We plan with 85 % of the rated capacity. Guides that use this figure cite the published measurements behind it.
- What the station uses on its own. The inverter draws power even with a small load plugged in. For a small appliance such as a CPAP, ignoring it can overstate runtime by a wide margin. We take this figure from the maker when it is published. When it is not, we use about 20 W and the page says it is our assumption.
- Starting power. Motors (fridge compressors, pumps, furnace blowers) draw more for a moment when they start. A station must handle that surge, not only the running load.
Your appliance’s rating plate, label or manual always beats our estimate.
Safety comes before sizing
Our guides explain what a power station can run. They do not replace a licensed electrician for anything connected to your house wiring, or your doctor and equipment supplier for a medical device. We never publish wiring diagrams, and we never suggest feeding power back through an outlet.
How we choose the products we cover
- The product must fit the situation on the page (for example, enough capacity and surge for the appliance discussed).
- It must be sold in the United States, and we say when it is sold in Canada.
- Whether a brand pays a commission plays no part. See the affiliate disclosure.
What we have not done
- No bench tests, no use of the products ourselves, no cold-room or long-term reliability data.
- No visits to stores or installers.
Each guide has a “What we checked, and what we didn’t” box near the end so you can judge for yourself.
How we keep guides current
- Each guide shows the date it was last reviewed and a revision history.
- Product links and specifications are re-checked at least every three months, and as soon as a reader reports a change; discontinued or changed models are updated or removed.
- Corrections from readers are welcome: see Contact.