How we rank power stations
Every power station gets a score from 0 to 100, shown as 1.0–5.0 stars. The score is a weighted sum of the components below. Value, output and portability are normalized within each size class, because they scale with capacity; recharge rate and features are normalized across the whole catalog, with the top and bottom 5% clipped so one outlier cannot distort the scale. Nothing is hand-adjusted, and manufacturers have no input.
The components
| Component | Weight | What it measures | Why it matters |
|---|---|---|---|
| Value | 25% | Rated watt-hours per dollar at current street price, compared within the size class | The single biggest driver of whether a unit is worth buying. We show the inverse ($ per kWh) on every page. |
| Output | 15% | Continuous AC watts divided by capacity, capped at 2.5 W/Wh, compared within the size class | A 1kWh unit with a 1800W inverter can run tools and appliances a 500W inverter cannot. |
| Chemistry | 15% | LiFePO4 scores 1.0; NMC scores 0.25. Cycle rating adjusts within chemistry. | LiFePO4 typically lasts 3,000 to 6,000 cycles versus 500 to 800 for NMC, and is more thermally stable. |
| Recharge | 15% | Max AC input watts divided by capacity (C-rate), capped at 1.5 | A unit you can refill in an hour during a brief outage is far more useful than one that needs eight. |
| Portability | 10% | Watt-hours per pound, compared within the size class | Energy density. A unit that is heavy for its size is harder to move and usually older. |
| Features | 10% | Points for UPS switchover of 20 ms or less (2), app (1), expandable (1), 240V (1), USB-C of 100W or more (1), solar input of 400W or more (1), wireless pad (0.5) | Small weight on purpose. Features matter, but not as much as the battery and inverter. |
| Measured | 10% | Independently measured usable capacity as a percent of rated Wh (median across sources) | Rated Wh is a marketing number. Delivered Wh is the truth. When no measurement exists this component is dropped and the other weights rescale, so unmeasured units are neither penalized nor rewarded. |
Size classes
Rankings are shown within size classes, because cross-class comparisons are rarely what a buyer needs:
- Small (under 500 Wh) — Phones, laptops, CPAP overnight, camera batteries. Carry-on friendly.
- Medium (500–1,499 Wh) — Weekend camping, mini-fridge, power tools, short outages.
- Large (1,500–2,999 Wh) — Multi-day outages, full-size fridge, RV and van life.
- Extra Large (3,000 Wh and up) — Whole-home backup, 240V, expandable systems.
Where the data comes from
Specifications come from manufacturer spec sheets. Prices are approximate street prices and are refreshed periodically; the retailer price at checkout is what applies. Measurements come from the reviewers and labs we track: for each we store the number, the unit, the source and a link, and never copy a reviewer's text. Where a source is paywalled, we record only that a test exists. See the reviewers and labs we track.
What we don't do
- We don't accept payment, sponsorship or free products for placement.
- We don't adjust scores by hand. If a ranking looks wrong, the fix is a data correction or a formula change, and formula changes are noted on the updates page.
- We don't rank power stations we can't find a spec sheet and a current price for.
Affiliate disclosure
Links to retailers are affiliate links and may earn us a commission at no cost to you. We link to every ranked power station the same way, so there is no incentive to favor one over another.