Battery Data Standard

battery-data-standard is a local Python library and command-line tool for turning battery cycler exports into validated, analysis-ready CSV or Parquet outputs with auditable conversion reports. It is intended for laboratories, battery test teams, and data pipelines that need a repeatable private path from vendor files to downstream tools such as DuckDB, Polars, PyBaMM, PyProBE, cellpy, BEEP, and Battery Archive-style workflows.

The package is vendor-neutral and independent. It is not certified by any cycler vendor or standards body. Adapter support describes behavior implemented and validated by this project; users should verify representative exports from their own cycler software before using the package in automated production workflows.

Installation

Python 3.10 or newer is required.

pip install --upgrade battery-data-standard

Optional extras are available for additional input formats:

pip install "battery-data-standard[yaml]"
pip install "battery-data-standard[matlab]"
pip install "battery-data-standard[mpr]"

The package installs the bds command and exposes both the full package name and a short import alias:

import battery_data_standard as bds
# or
import bds

Scope

The package provides:

• conversion of supported battery cycler time-series exports to standardized CSV or Parquet files;
• conversion of supported EIS tables to a standardized EIS table;
• cycler detection, data-kind detection, validation, conversion reports, and batch manifests;
• single-file diagnostics that explain detection, mapping, current-sign evidence, repairs, validation, and recommended next actions;
• intake audit reports with file-level conversion quality scores;
• archive-aware batch conversion for directories, zip archives, and tar archives;
• optional profile files for lab-specific column naming.

The package does not upload source data to an external service. It reads local files and writes local outputs.

Command-Line Usage

Inspect the installed version:

bds --version

Detect a cycler export:

bds detect raw_export.csv

Explain how one file will be detected, mapped, validated, and exported:

bds explain raw_export.csv --text
bds explain raw_export.csv --html report.html --xlsx report.xlsx --json report.json

Convert a time-series file:

bds convert raw_export.csv normalized.bds.csv --cycler auto --report auto

--report auto writes normalized.bds.report.json and normalized.bds.report.pdf next to the converted CSV. Add --report-format html or --report-format xlsx when those review formats are needed.

Export directly to a downstream staging format:

bds convert raw_export.csv pybamm_drive_cycle.csv --target pybamm
bds convert raw_export.csv pyprobe_staging.parquet --target pyprobe --format parquet

Validate a converted file:

bds validate normalized.bds.csv

Convert a directory or archive and write a JSONL manifest:

bds batch raw_exports normalized_exports --recursive --manifest manifest.jsonl
bds batch raw_exports.zip normalized_exports --manifest manifest.jsonl

Audit a raw folder before committing to conversion:

bds audit raw_exports --recursive --json audit.json --html audit.html

The audit report scores each raw data file and highlights conversion failures, missing required fields, unit conversions, time-axis repairs, current-sign evidence, duplicate timestamps, non-monotonic time, suspicious flat voltage/current, and cycle/step anomalies. Optional-column coverage is reported separately so small but valid fixtures are not treated as low-quality data just because they omit fields such as temperature or energy.

Inspect runtime adapter metadata and the pinned schema:

bds doctor raw_export.csv
bds formats
bds inspect-schema

Use bds doctor when a file fails or when you need a short troubleshooting report with adapter candidates, missing required columns, suspicious headers, suggested next steps, and a minimum anonymized fixture checklist. bds formats also reports each adapter's support tier and evidence tier so users can tell whether support is backed by public fixtures or unit tests.

Python API

Read a supported time-series export into a Polars dataframe:

import bds

df = bds.read("raw_export.csv", cycler="auto")

Show the user-facing export column names defined in the export template:

import bds

export_df = bds.to_export_frame(df)
print(export_df.columns)

Preserve Raw Current Sign And Repair Time Axis

For real experimental datasets, it is often useful to preserve the current sign exactly as recorded by the source file, allow documented time-axis repairs, and record any regular-sampling gaps:

df = bds.read(
    path,
    cycler="auto",
    current_sign="preserve",
    repair_policy="repair",
    time_sampling_policy="repair",
)

Use current_sign="preserve" when downstream analysis should keep the raw charge/discharge sign convention from the instrument. Use repair_policy="repair" when the pipeline accepts documented normalizations such as shifting elapsed test time to start at zero or sorting non-monotonic time values.

When a fixed sampling interval is detected, BDS checks for missing time points. By default, missing points on that regular grid are interpolated with time_sampling_interpolation="linear" and recorded in the conversion report. Use time_sampling_policy="warn" to report gaps without inserting rows, or set time_sampling_interval_s=1, 2, 10, or another known interval when the sampling cadence is defined by the test protocol.

Use an explicit cycler when the source format is known:

df = bds.read("arbin_export.csv", cycler="arbin")

Convert a file and keep the conversion report:

report = bds.convert(
    "raw_export.csv",
    "normalized.bds.csv",
    cycler="auto",
    report_path="auto",
)

This writes the converted CSV plus JSON and PDF reports. HTML and Excel reports can be added with report_formats=("html", "xlsx").

Write a downstream staging table by selecting an export target:

bds.convert("raw_export.csv", "pybamm_drive_cycle.csv", target="pybamm")
bds.convert("raw_export.csv", "cellpy_staging.csv", target="cellpy")

Read data and report information in memory:

df, report = bds.read_with_report("raw_export.csv", cycler="auto", strict=False)

Create step-level or cycle-level summaries from a normalized dataframe:

steps = bds.summarize_steps(df)
cycles = bds.summarize_cycles(df)

Output Model

The converter standardizes supported cycler exports into a BDS time-series table. Every successful default export contains three required fields:

Field	Unit	Description
Test Time (s)	s	Elapsed time from the start of the test.
Voltage (V)	V	Measured cell or channel voltage.
Current (A)	A	Measured current.

Additional fields, such as cycle number, step number, capacity, energy, temperature, power, and internal resistance, are included when they are available in the source file.

The default BDS CSV and Parquet exports use user-facing labels with units in parentheses. Lower-level adapter data may use internal labels; prefer bds convert or to_export_frame(..., target="bds") for public handoff.

Supported Format Families

The package includes adapters for NEWARE, Arbin, Maccor, BioLogic, Repower, PEC, Novonix, BaSyTec, LANDT, and generic tabular exports. Generic readers support delimited text, Excel, MATLAB, and Parquet inputs where the file contains or can be mapped to time, voltage, and current columns.

BioLogic .mpt text exports are supported by default. Binary BioLogic .mpr files are supported through the optional mpr extra, which installs the galvani backend.

See docs/supported-formats.md for adapter scope and support-tier definitions.

EIS Data

EIS files use a separate standardized table from row-wise time-series data. Use EIS-specific commands or API functions for known impedance files:

bds detect-kind impedance.csv
bds convert-eis impedance.csv normalized.eis.csv

eis = bds.read_eis("impedance.csv")
report = bds.convert_eis("impedance.csv", "normalized.eis.csv")

read() and convert() are time-series entry points. batch and batch_convert() can route mixed directories and archives that contain time-series files, EIS files, including Gamry .DTA ZCURVE files, and unsupported helper files.

Profiles

Profiles map lab-specific column names to canonical column names. JSON profiles are supported by the base installation. YAML profiles require the yaml extra.

{
  "columns": {
    "test_time": "time_seconds",
    "voltage": "cell_voltage",
    "current": "cell_current"
  }
}

Use a profile from the CLI:

bds convert lab_export.csv normalized.bds.csv --cycler generic --profile profile.json

Current Sign Convention

The default current convention is charge-positive and discharge-negative.

Use --current-sign preserve to retain the source sign convention, or --current-sign discharge-positive when a downstream workflow requires discharge-positive current. When a source file contains a recognizable charge/discharge status column, adapters use it to normalize current sign more explicitly.

BDS can record a warning-only adjacent-point current-sign sanity check in conversion metadata and audit records when current_sign is charge-positive or discharge-positive. Use --current-sign-check adjacent to enable this O(n) heuristic for files that need extra sign review.

Validation and Reports

Every conversion returns a machine-readable report with schema version, row count, columns, validation status, warnings, provenance, adapter metadata, repair operations, and time-sampling findings. With report_path="auto", BDS writes JSON and PDF reports by default; HTML and Excel reports are optional formats.

Strict validation is enabled by default. Repairable issues are reported with the default repair_policy="warn". Use repair_policy="repair" or --repair-policy repair only when the pipeline explicitly accepts the documented normalizations.

Documentation

Public documentation is in the docs directory:

• Python API reference
• Supported formats
• Export template
• Export targets
• Schema compatibility
• Diagnostics and audit reports
• Current sign convention
• Step and cycle semantics
• BDF compatibility status
• Warning and issue codes
• Fixture contribution guide
• Ecosystem integrations

License and Attribution

This project is distributed under the MIT License. See NOTICE.md for the project independence notice.