# Surkibat 20V Battery, 7.5Ah Li-ion Compatible with Dewalt

- Manufacturer: Surkibat
- Tier: F
- Price: $25.00
- Stated capacity: 7.5 Ah
- Amazon listing: https://www.amazon.com/dp/B0GJ5VV9HN?tag=lithiumsteppe-20
- Battery page: https://www.lithiumsteppe.com/battery/surkibat_7_5ah

## Summary

This pack will start smoking under normal operation. Bad engineering. Do not buy.

## Ratings

- **Honesty**: 1.3/5 — Actual capacity 3.1Ah. Massively overstated.
- **Durability**: 2.1/5 (teardown 3/5, cycling 1.2/5) — Decent built quality, except for the fact that it catches on fire when you use it.
  - Teardown notes: Decent overall mechanical build (tool electrodes ok, busbar attachment ok) but a structural flaw causes thermal runaway and fire under load.
- **Capacity**: 2/5 — 3.1Ah measured, averaging 1550 mAh/cell. Extremely poor.
- **Power**: 0.5/5 — Performed middle/bottom of the tiers on the performance and failure tests.
- **Safety**: 0.5/5 — Pack design has a structural flaw -- fire hazard even under normal use.

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

## Testing statistics

- Stated capacity: 7.5 Ah (135 Wh @ 18 V)
- Measured capacity: 3.1 Ah (55.8 Wh @ 18 V)
- Pack internal resistance: 80.7 mOhm
- High-power cycles survived: 4
- Peak sustained power: 787 W
- Energy delivered (failure test): 20.8 Wh

## Cell notes

Unbranded cells, potentially reclaimed.

## Test data

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

- **Pack Internal Resistance Test** (rinternal): Pack Resistance: 80.7 mOhm (average value of pack resistance between 17.5 and 18.5 V)
  - CSV: [rinternal.csv](tests/rinternal.csv)
  - Bench source file: surkibat_7_5ah/rinternal_surkibat_7_5ah_260512-15-35-55_0.csv
- **Capacity Test** (capacity): Capacity: 55.8 Wh (41% of stated 7.5 Ah @ 18V Nominal)
  - CSV: [capacity.csv](tests/capacity.csv)
  - Bench source file: surkibat_7_5ah/capacity_surkibat_7_5ah_260519-08-07-37_rerun.csv
- **Cycling Test** (performance): High-power cycles survived: 4. Failure mode: Stopped before tool cutoff
  - CSV: [performance.csv](tests/performance.csv)
  - Bench source file: surkibat_7_5ah/performance_surkibat_7_5ah_260518-12-04-46_1.csv
- **Failure Test** (failure): Energy discharged: 20.8 Wh, Peak power: 787 W
  - CSV: [failure.csv](tests/failure.csv)
  - Bench source file: surkibat_7_5ah/failure_surkibat_7_5ah_260518-12-59-05_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 — Heat buildup led to a plastic fire on the cell housing
- Teardown 2: photos/teardown_2.jpg — Undersized busbar/PCB connection completely melted
- Teardown 3: photos/teardown_3.jpg — De-soldered busbar and PCB junction
- Teardown 4: photos/teardown_4.jpg — Corner of pack melted / combusted
- Teardown 5: photos/teardown_5.jpg — High quality tool contacts despite poor electrical design
- Teardown 6: photos/teardown_6.jpg — Cell label: + RH YG18650 OF10C 24DEC16 3.6V

## 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: 2026-07-16T19:29:37.571Z (site commit a353b4a)
Contact: https://www.lithiumsteppe.com/contact
