The ETENWOLF S0 is a mini cordless tire inflator built for cyclists and compact car owners. Powered by a brushless motor, it delivers 15 L/min airflow and reaches 150 PSI in a 245 g package — light enough to clip onto a cycling kit, capable enough to inflate a 700C × 25C road bike tire from 0 to 100 PSI in 1 minute 57 seconds on a full charge.
15 L/min
Max Airflow
150 PSI
Max Pressure
2,400 mAh
Battery
245 g
Weight
±1 PSI
Accuracy
9 Tires
Per Charge
150 PSI Max Pressure, ±1 PSI Accuracy Across Full Range
The S0 reaches a verified maximum of 150 PSI, confirmed with a calibrated digital pressure gauge. Pressure accuracy is ±1 PSI across the full operating range — tested at 30, 60, 100, and 130 PSI with 3 readings per point per ANSI B40.7 methodology. For road bike tires where target pressure typically runs 80–120 PSI, this level of accuracy eliminates the guesswork that leads to pinch flats or sluggish rolling resistance.
15 L/min Airflow — 9 Road Bike Tires on One Charge
At 0 PSI no-load (ambient 25°C, calibrated flow meter, 10 s stable), the S0 delivers 15 L/min via its brushless motor (rated 1,000+ hours). One full charge handles 9 complete inflation cycles on a 700C × 25C road bike tire from 0 to 100 PSI. The S0 supports both Presta and Schrader valves via the included adapter — no tools required to switch.
| Inflation Test Data — 25 ± 2°C, 50 ± 10% RH, Battery 100%, Supplied Hose | |||
|---|---|---|---|
| Tire Type | Start PSI | Target PSI | Time (seconds) |
| 700 × 25C road bike (Presta) | 0 | 100 | 117 |
| 27.5″ × 2.125″ mountain bike | 0 | 35 | 126 |
Brushless Motor — 1,000+ Hour Rated Lifespan
The S0 uses a brushless motor — the same motor architecture found in premium power tools rather than entry-level tire inflators. Brushless motors eliminate the carbon brush wear mechanism that limits conventional motors to roughly 500 hours of operation. The S0’s motor is rated for 1,000+ hours of continuous operation, with no brush replacement required over the product lifecycle.
2,400 mAh — Full Charge in 1 Hour 13 Minutes
The S0 uses a Hanwei lithium cell rated at 2,400 mAh (8.88 Wh), charged via PD USB-C at 10W. From fully depleted to 100%, charge time is 1 hour 13 minutes using a 10W PD charger at 25°C. Charge-while-inflate is not supported. Battery standby life: confirmed to start and operate normally after 36 months of storage at recommended charge level (100%), with a top-up interval of every 12 months.
Noise: 79.1–83.2 dB(A) at 1 m
Measured across three production samples at 1 m from the front face, background noise below 30 dB(A), under full operating load. Sample 1: 83.2 dB(A), Sample 2: 81.7 dB(A), Sample 3: 79.1 dB(A). Equipment: calibrated sound level meter, A-weighted.
Technical Limits & Verified Edge Cases
The S0 was tested at the operational boundaries that most manufacturers leave undocumented. These are verified results from engineering tests.
| Continuous operation | 100% duty cycle confirmed — continuous inflation does not trigger thermal protection |
| Battery below 20% | Inflation speed slightly reduced as cell voltage drops. Max pressure unchanged — still reaches 150 PSI. |
| Cold soak −10°C (2 hours) | Unit starts and operates normally. Inflation speed slightly reduced due to lower battery discharge performance at low temperature. |
| Long-term storage | Store at 100% charge. Max 36 months. Top-up every 12 months. Confirmed starts normally after 36 months. |
| Operating temp range | −20°C to +60°C. Performance slightly reduced at low temperatures. |
Compatible Applications
The S0 is optimized for small-volume, high-pressure inflation: road bikes, mountain bikes, compact cars, and sports balls. It is not designed for full-size sedan or SUV tire inflation from flat — those use cases require the S1 or larger.
- Road bikes: Giant, Merida, Cannondale — both Presta and Schrader valves supported
- Mountain bikes: 27.5″ and 29″ formats tested
- Compact cars (top-up only): MINI Cooper, Fiat 500, Smart Fortwo
- Sports balls: Basketball, football, volleyball, rugby
- Not recommended for: Full sedan/SUV inflation from 0 PSI — low volume capacity makes this inefficient. Use S1 or S3 instead.
S0 vs S1: Which One Do You Need?
The S0 and S1 serve different primary use cases. The S0 at 245 g and 15 L/min is the choice for cyclists and compact car owners who prioritize portability. The S1 at 525 g and 20 L/min is the choice for sedan drivers who need to inflate full car tires efficiently.
| Parameter | S0 | S1 |
|---|---|---|
| Max Airflow | 15 L/min | 20 L/min |
| Max Pressure | 150 PSI | 160 PSI |
| Battery | 2,400 mAh / 8.88 Wh | 5,200 mAh / 19.24 Wh |
| Weight | 245 g | 525 g |
| Dimensions | 94 × 76 × 40 mm | 169 × 67 × 54 mm |
| Motor | Brushless | Brushless |
| Best for | Cyclists, compact cars | Class A/B sedan drivers |
Third-Party Certifications
All certifications issued by independent third-party laboratories. Report numbers provided for traceability.
| Certification | Report No. | Issuing Body | Date |
|---|---|---|---|
| CE (EMC + LVD) — EU CE Marking | WTH25H09245616E | Shenzhen Walter Inspection Group | 2025-09-11 |
| FCC — FCC Equipment Authorization | WTH25H09245622E | Shenzhen Walter Inspection Group | 2025-09-19 |
| UN38.3 (Lithium Battery) — UNECE TDG | WTH25D09245621B | Shenzhen Walter Inspection Group | 2025-09-26 |
| MSDS | WTH25D09245621B001 | Shenzhen Walter Inspection Group | 2025-09-26 |
| RoHS — EU RoHS Directive | WTH25X09245619C | Shenzhen Walter Inspection Group | 2025-10-22 |
| Design + Utility Model Patent | — | China NIPA | Active |
Frequently Asked Questions
How long does the S0 take to inflate a road bike tire to 100 PSI?
A 700C × 25C road bike tire from 0 to 100 PSI takes 1 minute 57 seconds (117 seconds) on a full charge at 25°C. A 27.5″ × 2.125″ mountain bike tire from 0 to 35 PSI takes 2 minutes 6 seconds (126 seconds).
How many road bike tires can the S0 inflate on a full charge?
9 tires. Tested on 700C × 25C, inflated from 0 to 100 PSI per tire at 25°C.
Does the S0 support Presta valves (road bike thin valves)?
Yes. The S0 supports both Presta and Schrader valves. Switching between them requires the included valve adapter — no tools needed.
Can the S0 inflate car tires?
Not recommended for full sedan or SUV tires from 0 PSI. The S0’s 2,400 mAh battery and 15 L/min airflow are optimized for small-volume, high-pressure applications (bike tires, sports balls). For car tire inflation, use the S1 (5,200 mAh, 20 L/min) or larger. The S0 can perform emergency top-ups on compact cars (MINI Cooper, Fiat 500) but is not suited to inflate from flat.
S0 vs S1 — which one should I choose?
Choose the S0 (245 g, 15 L/min, 150 PSI) if you are a cyclist or compact car driver who needs a pocketable inflator primarily for bike tires and occasional ball inflation. Choose the S1 (525 g, 20 L/min, 160 PSI) if you drive a Class A/B sedan and need to inflate full car tires efficiently.
Why does the S0 use a brushless motor?
Brushless motors eliminate carbon brush wear, the primary failure mechanism in conventional motors. The S0’s brushless motor is rated for 1,000+ hours of operation with no maintenance required. Conventional brushed motors typically reach end-of-life around 500 hours.
Does the S0 work at −10°C in winter?
Yes. After a 2-hour cold soak at −10°C, the unit starts and operates normally. Inflation speed is slightly reduced due to lower lithium cell discharge performance at low temperature. Max pressure is unaffected. Operating range: −20°C to +60°C.
How accurate is the S0 pressure gauge?
±1 PSI across the full operating range. Tested at 30, 60, 100, and 130 PSI with 3 readings per point, per ANSI B40.7 methodology.
