Methodology and data sources

Every specification page on ChargerAtlas is generated from a structured dataset with a documented origin. This page explains where each number comes from, how the data is cleaned, the exact formulas used in calculations, and — just as important — what the data cannot tell you.

Data sources

Chargers: EPA ENERGY STAR certified EVSE dataset

All 380 chargers in the database come from the U.S. EPA's public ENERGY STAR Certified Electric Vehicle Chargers dataset, retrieved through the official data.energystar.gov API. From each certification record we take the brand, model, maximum nameplate output current (amps), maximum output power (kW), input voltage, output cable length, network capability, and measured standby ("no vehicle mode") power draw. Every charger page links to its underlying EPA record in a Sources section.

Coverage follows from the source: ChargerAtlas lists only chargers that hold a current ENERGY STAR certification and are sold in the United States. Chargers that were never certified, or whose certification lapsed, are not in the database — absence here is not a judgment on quality.

Vehicles: curated from manufacturer documentation

The 29 EVs used for compatibility and charge-time pages are curated by hand from manufacturer specification documents. For each vehicle we record the charge-port connector (J1772 or NACS), the onboard AC charger limit in kW, usable battery capacity in kWh, EPA range, and model year, with the source document linked on each page where the vehicle appears.

Update frequency

The charger dataset is re-fetched from the EPA API on a recurring schedule and whenever ENERGY STAR announces certification changes. Each entity stores the date its record was retrieved; the sitemap's lastmod and this page reflect the newest retrieval in the current build. Current data snapshot: 2026-07-06 (380 chargers across 151 brands, 29 vehicles).

Data cleaning

• Records not marketed in the United States are excluded, and duplicate certifications of the same model keep only the most recently qualified record.
• EPA certification strings embed wildcard characters (*, #) for model-number variants; these are normalized for display without changing page URLs.
• A small set of manual overrides fixes display names (part numbers → product names) and corrects attributes against manufacturer spec sheets. Overrides are reviewed, not automated.
• Connector type is not part of the EPA record. We infer NACS from the product line (e.g. Tesla) and set it manually where the inference is wrong — see limitations below.

Compatibility verdicts

Charger ↔ EV compatibility is rule-based on the connector, with curated exceptions taking precedence:

• Compatible — charger connector matches the vehicle port.
• Adapter needed — J1772 charger with a NACS-port car (Tesla includes this adapter with its vehicles) or NACS charger with a J1772-port car (adapter sold separately).
• Incompatible — no adapter path exists between the connectors.

Where a specific charger/vehicle pair is known to deviate from the rule, a hand-maintained exception with an explanatory note overrides it.

Charge-time and electrical formulas

These are the exact formulas behind every computed number on the site:

• Real charging rate: min(charger max kW, vehicle onboard AC kW) — the slower side of the pair always sets the pace. A 19.2 kW charger charges an 11.5 kW-limited car at 11.5 kW.
• Empty-to-full time: battery kWh ÷ real rate kW, rounded to one decimal.
• Miles of range per hour: (EPA range mi ÷ battery kWh) × real rate kW, rounded to a whole number.
• Minimum breaker size: charger amps × 1.25, rounded up to the next 5 A step — the U.S. National Electrical Code treats EV charging as a continuous load that may use at most 80% of the circuit rating.

Limitations

• No charging-curve modeling. Charge times assume the nameplate rate for the whole session. Real sessions taper near 100% and vary with temperature, so treat times as comparable estimates, not stopwatch predictions.
• Nameplate, not measured, ratings. Power figures are the manufacturer's certified maxima, and battery capacities are manufacturer-stated usable figures.
• ENERGY STAR-only coverage. Popular chargers without current certification do not appear.
• No prices. The EPA dataset carries no pricing, so rankings never use price — see the editorial policy for how rankings are computed.
• No enclosure ratings. The EPA record does not state NEMA enclosure ratings, so outdoor suitability must be verified on the manufacturer's spec sheet — our outdoor installation guide explains how.
• Connector inference. Because the EPA record omits connector type, the NACS/J1772 field is heuristic plus manual correction; a misclassified unit is possible. Tell us if you spot one.

Data license

The raw charger specification rows in this database — as published on charger pages and in llms-full.txt — are available under CC BY 4.0: reuse them freely with attribution to ChargerAtlas (a link to this page is ideal). The underlying certification data is published by the U.S. EPA ENERGY STAR program and is in the public domain; ENERGY STAR is a registered trademark of the U.S. EPA, and nothing here implies EPA endorsement. The hand-curated EV list and the compatibility and charge-time derivations are not covered by this grant — all rights reserved.

Corrections

If any specification disagrees with the manufacturer's documentation or the EPA record, contact us with a link to the authoritative source. Verified corrections ship in the next build; systematic ones become ETL overrides so they survive dataset refreshes.