# VelgoNyx 8Ah Replacement Compatible for Dewalt

- Manufacturer: VelgoNyx
- Tier: C
- Price: $28.99
- Stated capacity: 8 Ah
- Amazon listing: https://www.amazon.com/dp/B0G7ZDM8D6?tag=lithiumsteppe-20
- Battery page: https://www.lithiumsteppe.com/battery/velgonyx_8ah

## Summary

All-around "not great" pack. Could work on a drill or other low-power tool. But at high power, despite having great cells, the pack has a tendency to get melted plastic on the contacts for your tool.

## Ratings

- **Honesty**: 1.8/5 — Measured capacity is 4Ah, half of the 8.0Ah claim.
- **Durability**: 1.1/5 (teardown 0.5/5, cycling 1.7/5) — Low-quality tool contacts risk getting melted plastic on your tool.
  - Teardown notes: Same low-quality tool electrodes as jnfkldsb and jyjzpb; plastic deforms onto tool contacts under load.
- **Capacity**: 3/5 — 4Ah measured capacity, half of the 8.0Ah claim.
- **Power**: 1/5 — Solid power delivery, but the plastic around the tool contacts will melt with extended use.
- **Safety**: 3/5 — No safety features and shoddy electric current routing.

Scoring rules: https://www.lithiumsteppe.com/methodology

## Testing statistics

- Stated capacity: 8 Ah (144 Wh @ 18 V)
- Measured capacity: 4.0 Ah (71.8 Wh @ 18 V)
- Pack internal resistance: 65.4 mOhm
- High-power cycles survived: 6
- Peak sustained power: 897 W
- Energy delivered (failure test): 32.7 Wh

## Cell notes

EVE Energy ICR18650/20P. Rated 30A max continuous discharge, 2000mAh capacity.

## Test data

Test procedures: https://www.lithiumsteppe.com/test-procedures

- **Pack Internal Resistance Test** (rinternal): Pack Resistance: 65.4 mOhm (average value of pack resistance between 17.5 and 18.5 V)
  - CSV: [rinternal.csv](tests/rinternal.csv)
  - Bench source file: velgonyx_8ah/rinternal_velgonyx_8ah_260514-16-56-03_0.csv
- **Capacity Test** (capacity): Capacity: 71.8 Wh (50% of stated 8 Ah @ 18V Nominal)
  - CSV: [capacity.csv](tests/capacity.csv)
  - Bench source file: velgonyx_8ah/capacity_velgonyx_8ah_260519-13-32-49_0_spliced.csv
- **Cycling Test** (performance): High-power cycles survived: 6. Failure mode: Battery thermistor reached cutoff
  - CSV: [performance.csv](tests/performance.csv)
  - Bench source file: velgonyx_8ah/performance_velgonyx_8ah_260521-09-55-04_0.csv
- **Failure Test** (failure): Energy discharged: 32.7 Wh, Peak power: 897 W
  - CSV: [failure.csv](tests/failure.csv)
  - Bench source file: velgonyx_8ah/failure_velgonyx_8ah_260521-11-04-56_0.csv

### CSV format

1 Hz samples. Lines starting with `#` are run metadata (test profile, battery profile, instrument identity, Arduino DAQ channel labels); the first non-`#` line is the column header. Columns vary by run date — Arduino DAQ columns (tc/v/r_ntc/fault) appear on runs logged since 2026-05-11.

- `ts_unix / ts_iso` — sample timestamp (Unix seconds / ISO-8601 local time)
- `elapsed_s` — seconds since test start
- `voltage_v` — pack voltage, V (4-wire remote sense)
- `current_a` — discharge current, A
- `active_power_w` — discharge power, W
- `discharged_ah / discharged_wh` — integrated charge / energy removed
- `phase / target / cycle` — load-profile phase name, setpoint, loop count
- `tc1_C..tc4_C` — Type-K thermocouple temperatures, Celsius (nan = channel absent, disabled, or faulted)
- `v0_V` — DeWalt C3 cell-tap voltage, V
- `v1_V` — DeWalt TH thermistor-pin voltage, V
- `r_ntc_ohms` — pack NTC thermistor resistance, ohms, derived per-tick from v1_V and pack voltage (DeWalt tool thermal cutoff reference: 2140 ohms)
- `fault1..fault4` — MAX31856 status byte per thermocouple, hex (00 = healthy)

## Photos

- Headline photo: photos/headline.png
- Teardown 1: photos/teardown_1.jpg
- Teardown 2: photos/teardown_2.jpg — Same pack design as other low-cost packs, jyjzpb and others
- Teardown 3: photos/teardown_3.jpg — Electrodes bend easily
- Teardown 4: photos/teardown_4.jpg — Case plastic melts easily
- Teardown 5: photos/teardown_5.jpg — Plastic melts onto electrodes and can ruin tool contacts
- Teardown 6: photos/teardown_6.jpg — Failed cell after failure test
- Teardown 7: photos/teardown_7.jpg — Cell label: ICR18650/20P 5NFD51M019938J 2.0Ah 7.2Wh

## Files in this dataset

- `README.md` — this file
- `site.json` — the published data record for this battery (machine-readable)
- `tests/{rinternal,capacity,performance,failure}.csv` — raw bench CSVs (see CSV format above)
- `photos/` — headline + teardown photos (captions above)
- `test_procedures.md` — the four bench tests
- `ranking_methodology.md` — how ratings are scored

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Source: Lithium Steppe (https://www.lithiumsteppe.com) — We test DeWalt-compatible power tool batteries on Amazon to guide your purchasing decisions.
Generated: 2026-07-16T19:29:37.717Z (site commit a353b4a)
Contact: https://www.lithiumsteppe.com/contact
