Neware BTS .nda / .ndax

Neware BTS battery testers save cycling data as .nda files (BTS 7–9) and .ndax zip files (BTS 8 and later). OpenReadout returns every measurement as one trace with time, voltage, current, capacity, energy, cycle and step channels, and a table of the executed steps. Derived from public files of five depositors (NewareNDA’s test files, navani, cellpy/IFE, SINTEF), with NewareNDA (BSD-3-Clause) read as documentation and used as a reference reader. Provenance: docs/provenance/neware.md. Crate: openreadout-echem.

format id	files	reads	confidence
neware-nda	.nda beginning NEWARE (BTS 7-9 battery testers)	versions 29 and 130 (both record layouts)	evidence rubric (docs/assurance.md)
neware-ndax	.ndax, a zip with data.ndc and XML descriptions (BTS 8+)	.ndc versions 5, 11, 14, 16, 17	evidence rubric

.nda layout

NEWARE and an eight-digit stamp (20200325), the version byte at offset 14.

• Version 29 (BTS 7). The header names its data section: u32 offset at 0x40, u32 length at 0x44, a whole number of 86-byte records. 0x55 0x00 records are measurements: u32 index (2), u32 cycle (6, zero-based), u16 program step (10), u8 step type (12), u64 step time in ms (14), i32 voltage in 0.1 mV (22), i32 current (26), four i64 accumulators (38: charge and discharge capacity, charge and discharge energy), the date as u16 year and five bytes (70), i32 current range (78). Current and accumulators are integers scaled by a factor that depends on the current range (NewareNDA’s table; the accumulators are in mA·s and mW·s). 0xAA records and 0x65 auxiliary records are not measurements (neither is decoded). The active mass is a u32 in µg at offset 152.
• Version 130, BTS 9.0. 88-byte records from offset 1024 whose first six bytes repeat (0x12, …, 0x55): from offset 4 of the record, step (5), step type (6), index (12), u64 step time in µs (24), f32 voltage (32) and current in mA (36), f32 charge capacity, charge energy, discharge capacity, discharge energy in mA·s / mW·s (48), u64 timestamp in µs since 1970 (64). No cycle number. A 0x81 record starts the footer.
• Version 130, BTS 9.1. 0x55 records from offset 1024, 52 bytes (or 56 with a temperature): step (2), step type (3), index (8), u32 seconds and nanoseconds of test time (12, 16; it does not restart at a step), f32 current in mA (20) and voltage (24), one signed f32 capacity and one energy accumulator (28, 32; positive while charging), u32 cycle (36), u32 seconds and nanoseconds since 1970 (44), f32 temperature (52). A 0x81 record starts the footer.

.ndax layout

A zip: data.ndc and, from version 11, data_step.ndc, data_runInfo.ndc, one data_AUX_<channel>_<type>_<n>.ndc per auxiliary channel, data_log.ndc, data_es.ndc, and the XML files VersionInfo.xml (software and firmware versions), TestInfo.xml (channel, program name, barcode, start and end, auxiliary channels), Step.xml (the program). The XML declares GB2312.

Every .ndc file: a 4096-byte header (byte 0 file type: 1 data, 5 auxiliary, 7 step, 18 run information; byte 2 version) and 4096-byte pages. A page: u16 kind (file type + 1), u16 record count, a validity bitmap, the records (from offset 132; 125 in version 5), and the CRC-32 of the first 4092 bytes in its last four. The reader refuses a page whose CRC or count does not hold.

file	version	record
data.ndc	5	87 bytes, marker 0x55 at 7: index (8), cycle (12), step (16), step type (17), u64 step time in ms (23), i32 voltage in 0.1 mV (31), i32 current (35), four i64 accumulators (43), date (75), current range (82)
data.ndc	11, 16	f32 voltage in 0.1 mV, f32 current in mA
data.ndc	14, 17	f32 voltage in V, f32 current in A
data_step.ndc	11, 14 (37 bytes); 16, 17 (100 bytes)	i32 cycle (zero-based), i32 program step, step type at 24
data_runInfo.ndc	11 (47), 14 (55), 16, 17 (100 bytes)	i32 step time in ms (0), four f32 accumulators (5; A·s in 11/16, A·h in 14/17), i32 logging interval in ms (29), i32 seconds since 1970 (33), i32 step number (37), i32 record index (41), i16 milliseconds (45)
data_AUX_c_t_n.ndc	14, 17	one f32 per record; t + 100 is the ChlType of TestInfo.xml (102 voltage, 103 temperature)

Only some records have a run-information record: the tester logs one when the logging interval changes, at a step change, and periodically. A record in between took the previous logged record’s interval; its step time is reconstructed from it (reported as assumed). Capacities and energies exist only on logged records; the reader returns NaN for the others.

What the reader returns

One trace records (every measurement, in file order):

channel	unit	from
time	s	test time: stored (BTS 9.1), or the step times accumulated (a new step begins on the instant the last one ended)
step_time	s	stored (not in BTS 9.1 files)
voltage	V
current	mA	negative while discharging
charge_capacity, discharge_capacity	mA·h	per step, as the tester accumulates them
charge_energy, discharge_energy	mW·h	per step
cycle	—	stored cycle + 1 (absent in BTS 9.0 files)
step_index	—	program step
step_type	—	code; extra.step_types names them
record	—	the record’s index
temperature	°C	BTS 9.1 56-byte records
aux_voltage_n, aux_temperature_n, aux_<type>_n	V, °C, —	.ndax auxiliary files

Step types: 1 cc_charge, 2 cc_discharge, 3 cv_charge, 4 rest, 5 cycle, 7 cccv_charge, 8 cp_discharge, 9 cp_charge, 10 cr_discharge, 13 pause, 16 pulse, 17 simulation, 19 cv_discharge, 20 cccv_discharge, 21 control, 22 ocv, 26 cpcv_discharge, 27 cpcv_charge.

A table steps: one row per executed step (first and last record, cycle, program step, step type, duration on the time axis, the last logged charge and discharge capacity).

Experiment: vendor Neware; start from the first record (tester local time for the calendar stamps of version 29 and .ndc 5, UTC for the others); duration; active mass (version 29); program name, barcode and end time (.ndax); software version. Findings: time_vs_clock when the tester’s clock advances more than the time axis (pauses, clock changes), step_time_gap, logged_records, aux_not_decoded, aux_type_unknown, no_footer, index_order.

Validation

tests/series_oracle/mod.rs: NewareNDA 2024.x (BSD-3-Clause, run as a black box) returns the same voltage, current, step time (test time in BTS 9.1), capacities and energies (on logged records), cycle, program step, step type and record index on all 9 development files, and the same values for each auxiliary file. NewareNDA names the auxiliary channels of echem-cellpy-ife-ndax by sorted file name and so swaps them; we name them by the channel type in the file name. One .ndax depositor (SINTEF, Zenodo 20802274) is held out.

Vocabulary (public API of openreadout-echem, Neware)

identifier	meaning
NdaReader	reader of Neware .nda files
NdaxReader	reader of Neware .ndax files
NDA_FORMAT_ID	neware-nda
NDAX_FORMAT_ID	neware-ndax

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How this reader was derived, file by file: provenance log.