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Convert Neware .ndax files to CSV (Beta)

Open Neware BTS .ndax battery test files without BTSDA and get a clean CSV with cycle summary and dQ/dV.

Opens: NDA, NDAX, MPR, MPT, RES
Saves: CSV, XLSX

Convert

Cycler files
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.nda, .ndax, .mpr, .mpt, .res · up to 200 MB each, 20 files max
    Add more files

    Neware .nda or .ndax, BioLogic .mpr (or an .mpt text export), Arbin .res. Add several cells to convert them together.

    Options

    Adds specific capacity (mAh/g) columns. Leave 0 to use the mass stored in the file, if any.

    Choose how data points are grouped into cycles for the summary.

    More options

    Up to 4 cycles for the voltage and dQ/dV previews, e.g. “1, 2, 10, 50”. Empty = picked automatically.

    Bin width for the incremental capacity curves. 0 = automatic (1–10 mV from the data density).

    Capacity retention is relative to this cycle. 0 = first complete cycle.

    Your files are deleted after processing.

    Neware BTS 8 and 9 save each test as an .ndax file, and normally only BTSDA, Neware's Windows data analysis program, can export it. This page reads the .ndax directly and returns every data point as a CSV, plus a per-cycle summary, dQ/dV curves and an Excel workbook.

    How to convert NDAX to CSV

    1. Upload the .ndax exactly as BTS wrote it. An Excel or CSV file exported from BTSDA is not the same thing, and the upload form tells you so.
    2. Optional: enter the active material mass in mg to get mAh/g columns. The mass stored in an .ndax has no documented unit, so it isn't used.
    3. Leave Cycle numbering on As in the instrument software to match BTSDA.
    4. Download Name.csv (all points), Name - cycles.csv, Name - dQdV.csv and Name.xlsx.

    What the CSV contains

    One row per recorded point, with fixed column names and units in the name: time_s, datetime, cycle, step_index, step_type (Neware's own CC_Chg, CCCV_Chg, Rest…), current_A (positive while charging), voltage_V, charge and discharge capacity in Ah and energy in Wh counted from the start of each cycle, and step_time_s. Auxiliary channels follow as temperature_C for the first probe, then aux2_temperature_C, aux2_voltage_V and so on. A header row makes it ready for pandas, Origin, MATLAB or Excel.

    How close it is to BTSDA

    Test files covering .ndax data versions 2, 5, 11, 14, 16 and 17 (BTS 8.0 to 9.x) were converted and set against BTSDA's own exports of them, row by row. Every voltage, current, time and cycle value matched as far as the export prints digits, and cycle capacities matched within BTSDA's rounding.

    Two BTSDA behaviours are reproduced:

    • When a test's configuration tells BTSDA to start a new cycle at every charge after a discharge, the cycle column follows that rule, not the program's loop counter.
    • Some BTS versions store times in UTC while the test start is in lab time. The offset is detected and applied, and the file details mention it.

    Good to know

    • Large tests are fine: files up to 1 GB, up to 20 million points. The Excel data sheet stops at 1,048,575 rows; the CSV always has everything.
    • Several cells can be uploaded together (up to 20 files); you then also get one combined cycle summary.
    • Older single-file Neware data uses .nda; see NDA to CSV.

    More about what this tool reads and writes: Battery Cycler Data Converter.

    More with Battery Cycler Data Converter