README.md

---
license: cc-by-4.0
language:
  - en
size_categories:
  - 100M<n<1B
task_categories:
  - time-series-forecasting
  - tabular-regression
tags:
  - battery
  - lithium-ion
  - LCO
  - lithium-cobalt-oxide
  - "18650"
  - random-walk
  - dynamic-discharge
  - prognostics
  - state-of-charge
  - state-of-health
  - kalman-filter
  - particle-filter
  - NASA
  - PCoE
  - benchmark
  - bsebench
  - tier-2-canonical
  - parquet
  - bpx-1.1
pretty_name: "NASA RW 2014 — BSEBench Canonical (Tier 2)"
---

# nasa-rw-2014

**Tier 2 BSEBench-canonical** Parquet harmonization of the NASA PCoE
*Randomized Battery Usage Data Set* (2014, Bole, Kulkarni & Daigle).
Hosted under the [BSEBench](https://bsebench.org) organization for
filter-benchmark reproducibility.

## Disambiguation

This is the harmonization of the **2014 Random Walk** dataset, **not**
the older 2007–2008 NASA PCoE Battery Aging series (B0005, B0006,
B0007, B0018). The 2007 B-series is excluded from BSEBench v1.0 — see
the
[`nasa-rw-2014-raw`](https://huggingface.co/datasets/bsebench-org/nasa-rw-2014-raw)
card for the rationale.

## Status

🚧 **Harmonization pending** — placeholder dataset card. Awaiting :

1. Tier 1 raw mirror upload at
   [`bsebench-org/nasa-rw-2014-raw`](https://huggingface.co/datasets/bsebench-org/nasa-rw-2014-raw)
2. Publication of `bsebench-specs` v0.2.0 with the canonical
   `TimeSeriesSchema` Pydantic model
3. Implementation + testing of the NASA RW harmonization adapter at
   [`bsebench-datasets/src/bsebench_datasets/adapters/nasa_rw_2014.py`](https://github.com/bsebench-org/bsebench-datasets/blob/main/src/bsebench_datasets/adapters/nasa_rw_2014.py)

## What this will be

The NASA RW 2014 dataset (28 cells, 7 parts) converted to the
**BSEBench canonical Parquet schema** :

| Column | Type | Description |
|---|---|---|
| `cell_id` | string | identifier within the dataset (e.g. `RW1`, `RW2`, …, `RW28`) |
| `time_s` | float64 | seconds since experiment start (`t = 0` at first sample, monotonic across all cycles for a given cell) |
| `voltage_V` | float64 | terminal voltage, always positive |
| `current_A` | float64 | BPX-1.1 sign convention : charge = positive, discharge = negative |
| `temperature_C` | float64 | cell-surface thermistor reading ; nullable when channel is masked (RW3 caveat) |
| `cycle_number` | int32 | cycle counter, 1-indexed ; **a single counter** unifies Random-Walk segments and pulsed-load reference cycles |
| `step_id` | string | within-cycle step identifier (`rw_discharge`, `rw_charge`, `cc_charge`, `pulsed_ref`, `eis`, `rest`) |
| `capacity_Ah` | float64? | running coulomb-counted capacity (computed from `current_A` × `Δt`, sign per BPX-1.1) |

Partitioned by `cell_id` for parallel reading. **Expected size** :
~3-5 GB uncompressed, ≤ 600 MB after Zstandard compression (estimate
based on a 1 Hz sampling cadence and ≤ 200 days of cumulative recording
per cell ; verify after first end-to-end run).

## Mapping from original

The NASA RW `.mat` files use a nested MATLAB struct layout per cell :

```
data = struct(
    procedure = "Random Walk Cycling",
    description = "...",
    step = struct(
        type = ["D"|"C"|"R"|"P"|...],   % discharge / charge / rest / pulsed
        relativeTime = [...],             % seconds since cycle start
        time = [...],                     % MATLAB datenum
        voltage = [...],
        current = [...],
        temperature = [...],
        date = [...],                     % start of cycle
        comment = "..."
    )
);
```

The harmonization rewrites this into long-form Parquet with one row per
sample :

| `.mat` field | BSEBench column | Conversion |
|---|---|---|
| `step.relativeTime` (cumulative across cycles) | `time_s` | unchanged |
| `step.voltage` | `voltage_V` | unchanged |
| `step.current` | `current_A` | **sign flipped** (see below) |
| `step.temperature` | `temperature_C` | masked NaN if cell ∈ `{RW3}` (corrupted thermistor) |
| `step.type` | `step_id` | mapped to canonical step vocabulary |
| (cycle index) | `cycle_number` | re-numbered monotonically including reference cycles |

## Sign-convention notes

**The NASA PCoE Random Walk dataset uses the convention**
`positive current = discharge` (load) — the legacy convention common to
older battery test benches and NASA aerospace prognostics literature.

BSEBench follows **BPX 1.1**, which defines `positive current = charge`
(into the cell). The harmonizer therefore applies a **single sign flip**
when reading the `step.current` field :

```python
current_A_bsebench = -1.0 * step.current_nasa
```

This is documented per-cell in the manifest YAML so that auditors can
verify the conversion against Tier 1.

> **Caveat — confidence MEDIUM** : the discharge-positive convention
> for NASA PCoE Random Walk has not been confirmed from a primary NASA
> technical report at the time of this card's draft. Confirmation will
> be performed during adapter implementation by inspecting cycle
> end-points (a CC-discharge cycle should drive voltage *down*) and the
> result locked in the manifest with a verification SHA. If the
> convention turns out to be charge-positive, the sign flip is removed
> — the harmonization remains correct.

## Time origin

NASA stores absolute timestamps (`step.time` in MATLAB datenum format)
plus per-cycle relative timestamps (`step.relativeTime`). BSEBench's
`time_s` column is built by **concatenating relative times across
cycles** in chronological order, yielding a monotonic `time_s` from 0
through the cell's full operating life. Absolute MATLAB datenum is
preserved in the manifest YAML for users needing wall-clock alignment.

## Cycle numbering

A single `cycle_number` counter is used across both Random-Walk segments
and pulsed-load reference cycles. The `step_id` column distinguishes
their roles. This avoids the asymmetric cycle counters that appear in
the raw `.mat` (where reference cycles sometimes restart at index 0).

## Excluded cells

By default, two cells are flagged but **not removed** :

- **RW3** : `temperature_C` masked NaN throughout (corrupted channel).
- **RW20** : marked with a per-cell flag `quality_warn = true`. Rows are
  retained for completeness ; users running estimator-quality metrics
  should filter on `cell_id != 'RW20'`.

The default loader exposes these as opt-in / opt-out flags ; raw rows
are preserved verbatim in Parquet to allow downstream re-evaluation.

## Why "canonical" tier

This is the version **users should consume** for filter benchmarking.
It :

- Maps NASA's struct layout to BSEBench's standardized columnar schema
- Harmonizes sign convention to BPX-1.1
- Unifies cycle numbering across the seven parts and reference cycles
- Strips MATLAB-specific metadata not needed for state-estimation
- Loads in 1 line via `bsebench-datasets`

For provenance / audit, see the
[Tier 1 raw mirror](https://huggingface.co/datasets/bsebench-org/nasa-rw-2014-raw).

## Anchor standards

- Sign convention : [BPX 1.1](https://bpxstandard.com/) (charge = positive, discharge = negative)
- Time-series schema : [LF Energy BDF](https://lfenergy.org/lf-energy-battery-data-alliance-announces-the-battery-data-format-bdf/)
  (Dec 2025) where applicable

## License

- **Underlying NASA data** : public domain / CC0 1.0 (per NASA Open
  Data Policy and the NASA PCoE Data Repository terms — see the
  [Tier 1 card](https://huggingface.co/datasets/bsebench-org/nasa-rw-2014-raw)
  for the verbatim disclaimer).
- **BSEBench-derived harmonization layer** (column mapping, sign flip,
  Parquet schema, cycle numbering) :
  [CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/), per the
  BSEBench organization's standard policy for derived data.

Users who consume only the Tier 2 Parquet files should comply with
**both** licenses (CC0 for raw content + CC-BY-4.0 for the BSEBench
harmonization layer) — in practice this means citing both NASA and
BSEBench, which is what we recommend regardless.

## How to use (target API)

```python
# Once shipped (M2.1)
from bsebench_datasets import load_bsebench

ds = load_bsebench("nasa-rw-2014", revision="v1.0")
print(ds.chemistry)            # "LCO"
print(ds.cell_count)           # 28
print(ds.first_cell_data().head())  # canonical Parquet columns
```

## Citation

Cite the NASA PCoE record (no DOI) :

```bibtex
@misc{bole2014_nasa_rw,
  author    = {Bole, Brian and Kulkarni, Chetan S. and Daigle, Matthew},
  title     = {Randomized Battery Usage Data Set},
  year      = {2014},
  publisher = {NASA Ames Prognostics Center of Excellence (PCoE)},
  howpublished = {NASA PCoE Data Repository, Item~\#11},
  url       = {https://www.nasa.gov/intelligent-systems-division/discovery-and-systems-health/pcoe/pcoe-data-set-repository/}
}

@misc{bsebench2026,
  author = {Akir, Oussama and BSEBench Contributors},
  title  = {{BSEBench}: an open-source benchmark for battery
            state-estimation filters},
  year   = {2026},
  url    = {https://bsebench.org},
}
```

## Provenance

Derived from
[`bsebench-org/nasa-rw-2014-raw`](https://huggingface.co/datasets/bsebench-org/nasa-rw-2014-raw)
via
[`bsebench-datasets/src/bsebench_datasets/adapters/nasa_rw_2014.py`](https://github.com/bsebench-org/bsebench-datasets/blob/main/src/bsebench_datasets/adapters/nasa_rw_2014.py).
The harmonization script's commit SHA is recorded in the manifest YAML
at
[`bsebench-datasets/manifests/nasa_rw_2014.yaml`](https://github.com/bsebench-org/bsebench-datasets/tree/main/manifests).