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Methodology

How we test backup power equipment

This page documents the hands-on procedures each product goes through when we test it. Each product in a category is tested the same way, and we note here whenever a procedure changes. Reviews published before a product completes these tests are labeled research-based and carry no score.

Last updated:

Overview

Our evaluations are organized into four pillars. Each pillar produces measured results that feed into a weighted overall score (see Testing Standards). When a test cannot be completed on a product, we say so in the review rather than estimating a result.

Pillar 1: Battery lifecycle & heat dissipation

The goal is to find out how much energy a unit actually delivers, and how it handles heat while doing it.

Procedure

  1. Charge the unit to 100% and let it rest to room temperature.
  2. Connect a resistive AC load set to a heavy share of the unit's continuous rating, and log output with a power meter until the unit shuts off.
  3. Record total delivered watt-hours and compare them with the rated capacity.
  4. Log surface and vent temperatures throughout the run, and note any throttling, fan behavior, or early shutdown.

What we report

  • Usable AC watt-hours and the percentage of rated capacity delivered
  • Peak temperatures and whether output was reduced because of heat
  • Whether the unit sustained its advertised continuous output

Pillar 2: Inverter waveform purity

This pillar checks whether the AC output is clean enough for motors, sensitive electronics, and medical devices.

Procedure

  1. Capture the AC waveform with an oscilloscope at idle, under a steady resistive load, and while starting a motor or compressor load.
  2. Record output voltage and frequency stability across those conditions.
  3. Run a CPAP machine and common small electronics and note any faults, noise, or abnormal behavior.

We do not provide medical advice. Always confirm the power requirements of a medical device with its manufacturer before relying on any backup source.

Pillar 3: Real-world solar recharging

Solar input ratings assume ideal sunlight. We measure what a system actually takes in outdoors.

Procedure

  1. Pair the unit with its intended or recommended panels and set them up outdoors at a consistent angle.
  2. Log solar irradiance with a meter alongside the unit's measured charge input.
  3. Record time to charge across a defined range and compare it with the manufacturer's advertised solar charge time.

What we report

  • Peak and average solar input relative to measured sunlight
  • Real recharge time versus the advertised claim
  • Ease of setup, cable compatibility, and panel durability observations

Pillar 4: Cold & extreme weather readiness

Outages often happen during severe weather, so we look at behavior across a range of roughly −10 °C to 45 °C (14 °F to 113 °F).

Procedure

  1. Bring the unit to temperature and attempt to power on, charge, and discharge.
  2. Note where the battery management system blocks charging, reduces output, or prevents start-up.
  3. Compare behavior with the operating and charging temperature ranges in the manual.

Practical & safety checks

  • Port selection, labeling, display clarity, and app reliability where applicable
  • Weight, handles, and portability
  • Noise from fans during charge and heavy discharge
  • Warranty length, support access, and safety certifications listed by the manufacturer

Changes to this methodology

We update procedures as we learn. Material changes are listed here with a date, and older reviews are marked if their results were collected under a previous version.

  • October 11, 2026: Methodology published.