# Local LG 18650 NMC UDDS/RPT SOH Dataset

This dataset contains single-cell LG 18650 NMC lithium-ion battery measurements collected under dynamic operation, CC/CV charging, rest periods, and reference performance tests. It is intended for state-of-health (SOH) estimation, capacity-estimation, second-life battery analysis, and public-to-local transfer-learning studies.

The dataset provides a local target domain for evaluating whether SOH models trained on public battery-aging datasets can generalize to independently acquired laboratory data.

## Scope

This release contains data from one 18650 cell. It is suitable for reproducibility, method validation, and target-domain transfer evaluation. It should not be interpreted as a population-level aging study or a statistical study of cell-to-cell variability.

## Files

| File | Description |
|---|---|
| `LG_18650_NMC.csv` | Main time-series dataset |
| `data_dictionary.csv` | Column definitions, units, and notes |
| `protocol_description.md` | Test protocol and acquisition-system description |
| `checksums.sha256` | SHA256 checksum for file-integrity verification |
| `example_load_and_basic_checks.py` | Minimal Python script for loading and summarizing the dataset |
| `setup_photos/` | Optional setup photographs and captions, if included in the release |

## Experimental Setup

The experiment used a single 18650 cell holder connected to laboratory charge/discharge equipment and local measurement/control hardware.

| Equipment | Role |
|---|---|
| Rigol DP711 programmable DC power supply | Cell charging and CC/CV-style charge operation |
| Rigol DL3021 DC electronic load | Cell discharge, dynamic-load operation, and reference-discharge operation |
| Surface temperature probe | Cell casing temperature measurement |
| Local controller/data-acquisition hardware | Test control and data logging |

The dataset uses the following current convention:

```text
positive current = discharge
negative current = charge
```

## Protocol Overview

The dataset contains the protocol:

```text
real_udds_leq3v4_with_rpt
```

The protocol includes:

- UDDS-style dynamic operation;
- full CC/CV charging;
- reference charge;
- reference discharge;
- reference-discharge label windows;
- rest periods before/after dynamic operation and reference tests.

## Dataset Summary

| Item | Value |
|---|---:|
| Number of rows | 1,062,876 |
| Number of columns | 11 |
| File size | 122,047,374 bytes |
| Start time | 2026-02-27 13:47:22 UTC |
| End time | 2026-03-25 08:42:05 UTC |
| Main protocol | real_udds_leq3v4_with_rpt |
| Current convention | positive current = discharge, negative current = charge |
| Nominal capacity used in associated current-normalized experiments | 3.5 Ah |
| SOH range in file | 86.004875% to 100.0% |
| Capacity range in labeled rows | 2.768902 Ah to 3.219471 Ah |
| Sampling interval, median | 1 s |
| Duplicate timestamps | 51 |

## Segment Labels

| Label | Rows |
|---|---:|
| full_charge | 538,413 |
| rpt | 279,719 |
| udds | 230,671 |
| rest | 14,073 |

## Main Step Names

| Step name | Rows |
|---|---:|
| FULL_CHARGE | 512,481 |
| UDDS_PROFILE | 228,521 |
| REF_CHARGE | 91,715 |
| REF_DISCHARGE | 78,587 |
| REF_DISCHARGE_LABEL | 41,066 |
| REF_CHARGE_CLOSE | 39,217 |
| REST_AFTER_FULL_CHG | 23,420 |
| REF_PRECHARGE_TOP_OFF | 14,557 |
| REST_AFTER_REF_DIS | 6,249 |
| REST_AFTER_REF_CHG | 6,244 |

## Columns

| Column | Description |
|---|---|
| `datetime` | UTC timestamp |
| `step_name` | Detailed test-step name |
| `protocol` | Protocol identifier |
| `label` | Broad segment label: `udds`, `full_charge`, `rpt`, or `rest` |
| `current_a` | Cell current in ampere; positive = discharge, negative = charge |
| `temp_c` | Cell temperature in degrees Celsius |
| `voltage_v` | Cell terminal voltage in volts |
| `capacity_ah` | Sparse measured/reference capacity label in ampere-hours |
| `charge_ah` | Integrated charge/throughput state in ampere-hours |
| `soc_pct` | SOC estimate or test-controller SOC value in percent |
| `SOH` | Sparse SOH label in percent |

For additional detail, see `data_dictionary.csv`.

## SOH And Capacity Labels

The `SOH` and `capacity_ah` columns are sparse. They are populated mainly during reference-discharge-related rows.

| Column | Non-null rows |
|---|---:|
| capacity_ah | 119,622 |
| SOH | 119,622 |

In associated transfer experiments, SOH is interpreted as:

```text
SOH_percent = measured_capacity_ah / reference_capacity_ah * 100
```

The first reliable 100% SOH capacity in the file is approximately 3.219 Ah. Users should explicitly state the reference-capacity definition used in any downstream analysis.

## Recommended Use

This dataset can be used for:

- zero-shot or transfer-learning SOH estimation;
- capacity-estimation experiments;
- comparison of public-trained SOH models against local laboratory measurements;
- evaluation of SOH labels propagated from reference-performance-test states;
- embedded-BMS method development where only voltage, current, and temperature are available as online measurements.

When SOH is the target, users should not use `SOH` or `capacity_ah` as input features. These columns should be treated as labels or diagnostic references only.

## Suggested Preprocessing

Users should:

- parse `datetime` as UTC;
- sort rows chronologically;
- handle duplicate timestamps explicitly;
- check large time gaps before sequence modeling;
- preserve the current sign convention;
- separate directly measured reference-test labels from propagated aging-state labels when constructing supervised windows.

## File Integrity

```text
LG_18650_NMC.csv
SHA256: E5554C7AFA353627D1D0D8DA29EE8AC365E9FEC312DDCDCFBB828C144F081B4D
Size: 122,047,374 bytes
Rows: 1,062,876
Columns: 11
```

## Limitations

- The release contains one local cell.
- SOH and capacity labels are sparse.
- Some timestamps are duplicated.
- Large time gaps exist because the log spans multiple test sessions.
- The dataset supports target-domain/reproducibility evaluation, but additional local cells are needed for population-level generalization claims.

## Citation

Use the DOI generated by the data repository for citation.

Suggested citation format:

```text
Author(s), "Local LG 18650 NMC UDDS/RPT Dataset for Second-Life SOH Estimation and Public-to-Local Transfer", version 1.0.0, year, DOI.
```

## License

See the license selected in the data repository record.

