CalmWatt — Verified Backup Power for Everyday Homes

A suburban street at dusk during a power outage, with one house still lit

CalmWatt Research

Backup power, checked against the primary source.

Portable power stations and home backup, compared on numbers that mean the same thing across brands, plus safety data compiled from government records.

How we verify
About CalmWatt

units tracked

every one with a capacity the maker publishes

665

figures transcribed

each stored with the sentence it came from

manufacturer pages

the only place our numbers come from

No unit here has been physically tested. We compare what the makers publish, and say so when they publish nothing. How we verify.

What do you need to keep running?

A snow-covered house at night during a winter outage, its windows still lit

Appliance guideRun a gas furnace blower through a winter outageA gas furnace still needs its blower. We work out which units start it and how long they hold it.

A dark kitchen during a power outage, lit by an open refrigerator and a lantern

Appliance guideKeep a refrigerator running through a 12-hour outageWhich units carry a refrigerator for a full 12-hour outage, and which stall on the compressor’s starting surge.

Two printed specification sheets side by side with highlighted rows

ComparisonsTwo units, side by sideCapacity, real output, surge and cost per watt-hour, from each maker’s own pages.

A portable generator placed outdoors, well away from a house, in light rain

Reference dataGenerator safety, from the public recordCarbon monoxide deaths and recalls, compiled from CPSC records and free to cite.

Anker SOLIX C2000 Gen 2 vs Bluetti AC200L: manufacturer-published specifications compared — This is what a comparison here looks like. Every bar is a figure we transcribed from the manufacturer’s own product page, with the date we checked it. Values that are calculated, or that the manufacturer does not publish, are left off the chart rather than estimated. See this comparison · How we verify

Picked for one job

Five units ranked on the one measure that decides the job, with the arithmetic shown.

Single-unit reviews

Every published specification for one unit, what it runs, and what the maker does not state.

Recent model-to-model comparisons

See every comparison we have published →

Safety data from public records

Reference data · free to cite

Generator carbon monoxide deaths: the CPSC revision matrix

CPSC has revised its first-published generator CO death count upward every year since 2015 — by an average of 51.5%. We compared eight editions of the report and published the year-by-year table the agency does not.

Read the analysis · Download the CSV

Reference data · free to cite

Power station and generator recalls: a CPSC index

Our dataset holds 44 CPSC recall notices that our keyword search matched for generators and battery power stations, the earliest from 1989 — notices, not product units. By our classification: 8 battery power station, 33 engine-driven generator, 3 generator (type unclear). One table names the hazard in each, so a reporter or a buyer can check a model in one place.

Read the analysis · Download the CSV

A flashlight lighting a printed manual on a kitchen counter during an outage

Why this site exists

Home backup power is unusually hard to shop. The same battery capacity gets quoted three different ways, surge ratings are measured under conditions that are never stated, and prices swing thirty to forty per cent around sale events, so a review written six months ago can describe a product that no longer costs what it says.

The safety record sits in government PDFs built for filing rather than reading. CalmWatt works on both problems: it normalises the specifications so two products can be compared honestly, and turns the public safety record into datasets that stand up to being checked.

Our standards, in short

Primary sources, linked in place.If we cannot find the source, the number does not go in.

An organisational byline.No invented individual experts.

No affiliate links on reference data.A citation is worth less if the page is trying to sell something.

Visible corrections.When a figure changes, every page citing it changes in the same pass.

Read the full editorial guidelines · How we verify · Contact the editorial team