Electric Mopeds: A Fast-Growing Test Challenge
Electric mopeds (电动轻便摈托车) — the low-speed, low-power cousins of electric motorcycles — represent one of the fastest-growing segments of global urban mobility. In China alone, over 60 million electric two-wheelers are produced annually, with a significant share classified as light electric motorcycles under GB/T 7258: maximum design speed above 50 km/h but below 70 km/h, motor power typically 1–4 KW.
As Chinese regulators tighten enforcement of GB standards for two-wheeler motor performance, manufacturers face increasing pressure to certify motor performance before type approval. The test requirements for light electric motorcycles differ meaningfully from both standard electric bicycles (below 250W, 25 km/h) and full electric motorcycles (above 4 KW, 70 km/h) — requiring a dedicated test bench configuration.
Classification: Where Does Your Motor Fit?
Understanding the regulatory classification determines which test standard applies:
| Vehicle Type | Chinese Term | Velocidad máxima | Potencia del motor | Estándar |
|---|---|---|---|---|
| Electric bicycle (e-bike) | 电动自行车 | ≤25 km/h | ≤250 W. | GB 17761 |
| Light electric motorcycle | 电动轻便摈托车 | 25–70 km/h | ≤4 KW | GB/T 7258 + GB/T 36979 |
| Electric motorcycle | 电动摈托车 | >50 km/h | 4–11 KW | GB/T 7258 + GB/T 36979 |
| Electric motorcycle (high power) | 电动摈托车 | >50 km/h | >11 KW | GB/T 7258 + GB/T 36979 + additional |
The motor-specific standard, GB/T 36979, applies to all motor-powered two-wheelers above the e-bike threshold. Sin embargo, the test durations for peak torque differ by classification:
- Electric bicycle motors (≤4 kW peak, meeting light motorcycle threshold): Peak torque sustained for 30 artículos de segunda clase
- Full electric motorcycle motors (>4 KW): Peak torque sustained for 60 artículos de segunda clase
GB/T 36979 Test Items for Light Electric Motorcycle Motors
1. Continuous Torque and Power Test
The motor is run at rated voltage with torque increasing to rated continuous torque. The system must sustain rated torque for 30 minutos. Temperature rise during this period must not exceed the insulation class limit:
- Winding temperature rise: ≤80k (Class B), ≤105k (Class F), ≤125k (Class H)
- Bearing temperature: ≤55K rise over ambient
- Housing surface temperature: ≤65°C above ambient
2. Peak Torque Test (30 Artículos de segunda clase)
The key differentiator from e-bike and full motorcycle tests. The load dynamometer applies increasing torque to the motor output until the rated peak torque (from the product technical specification) is reached. The system must sustain this peak torque for a minimum of 30 continuous seconds.
Requirements during peak torque test:
- Battery voltage or supply voltage must remain within ±5% of rated voltage throughout
- Motor and controller must not trigger thermal protection cutback during the 30-second period
- Temperature must not exceed absolute limits at test end
- Load must reach 95% of peak torque within 2 seconds of test start
3. Maximum Working Speed
With rated voltage applied and minimum specified load, the motor must reach and maintain rated maximum speed (as specified in the product technical file) for at least 3 minutos. Stable operation is verified by checking that speed variation remains within ±2% of the setpoint.
4. Efficiency at Five Load Points
System efficiency (electrical input to mechanical output) is measured at five torque points as a fraction of rated continuous torque:
| Load Point | Esfuerzo de torsión (% rated) | Target Efficiency | Why This Point Matters |
|---|---|---|---|
| Light urban load | 50% | >72% | Flat road, city traffic |
| Partial load | 80% | >78% | Slight gradient |
| Carga nominal | 100% | >82% | Rated design point |
| High load | 150% | >78% | Moderate hill climb |
| Peak load | Peak torque | >70% | Maximum acceleration |
These efficiency requirements are lower than for full electric motorcycles (which must achieve >85% at rated load) — reflecting the simpler motor designs typical of the 1–4 kW moped segment.
5. T-N Characteristic Curve
The complete torque-speed curve from zero to maximum speed, measured at rated voltage. For moped hub motors, the T-N curve is particularly important because the legal speed limit (maximum design speed) is verified from this curve under load — not from free-running no-load speed, which is typically higher.
Test Bench Configuration for Light Electric Motorcycle Motors
Motor Types and Their Test Challenges
Light electric motorcycle motors fall into three categories, each with specific test bench requirements:
Hub Motors (Outer Rotor BLDC)
The most common type for mopeds. The motor is built into the rear wheel hub, rotating the rim directly. Test bench coupling uses a wheel-axle adapter that clamps the axle stationary while the dynamometer couples to the rotating rim. Output speed is low (200–800 rpm at the rim) with high torque (20–80 N·m at the rim).
Mid-Drive with Internal Reduction
Less common in the moped segment, more common for higher-power light motorcycles. The motor shaft spins at 3,000–6,000 rpm; after reduction gear, output is 300–800 rpm. Test bench can connect at either the motor shaft or the output shaft — output shaft is preferred for type approval testing.
Geared Hub Motors
Combine a small high-speed motor with a planetary reduction gear inside the hub. Output speed is lower than direct-drive hubs, torque is higher. The gearbox efficiency loss must be included in system efficiency measurements.
Recommended Test Bench Specification
| Parámetro | Especificación |
|---|---|
| Motor power range | 100 W. – 5 KW |
| Output shaft speed range | 0 – 2,000 rpm |
| Output torque range | 0 – 200 N·m |
| Torque sensor accuracy | ±0.1% FS |
| Power analyzer accuracy | ±0.2% (DC input at controller terminals) |
| Temperature channels | 8 thermocouple inputs (devanado × 2, cojinete × 2, housing × 2, ambiente × 1, controller × 1) |
| Battery simulator | 36V – 96V, 0–100A bidirectional |
| CAN interface | CAN 2.0A/B (for controller diagnostic readout) |
| Coupling adapters | Hub axle adapter, spline adapter, chain sprocket adapter |
| Standards compliance | GB/T 36979, GB/T 7258, GB/T 34660 |
| EoL test cycle time | 8–15 minutes per motor |
End-of-Line Testing for Production
Beyond R&D and type approval, moped motor test benches play a critical role in production quality control. Con 60+ million motors produced annually in China, end-of-line (EoL) testing must be fast, automated, and highly reliable.
A typical EoL test sequence for a 1.5 kW moped hub motor (target: 10 minutes total):
- No-load run (2 min): Run at 500 rpm and rated speed — check for abnormal noise, current draw, bearing vibration
- Rated point check (3 min): Apply rated torque at rated speed — verify efficiency within acceptance band (±3% of type-approval value)
- Peak torque brief check (30 sec): Apply peak torque — verify current limit, no fault codes
- Temperature check: Verify winding temperature rise at rated load is within limits
- Automated pass/fail: All data logged against serial number, report generated
A well-designed EoL system handles 40–60 motors per 8-hour shift — essential for production volumes in this segment.
Preguntas frecuentes
Does GB/T 36979 testing require a certified test laboratory?
For type approval submitted to MIIT (Ministry of Industry and Information Technology), the test must be conducted at an accredited laboratory listed in the CATARC or equivalent approved testing agency database. For internal quality control and supplier qualification, manufacturers can use their own calibrated test benches.
What voltage does the test bench use — battery or power supply?
GB/T 36979 specifies testing at rated battery voltage (±5%). A programmable DC power supply simulating the battery is preferred over an actual battery pack — it provides stable voltage under load, allows precise voltage setting, and eliminates battery SOC variation. The supply must be capable of sourcing the peak current during the 30-second peak torque test.
How does the 30-second test differ from the 60-second test for full motorcycles?
The 30-second duration for light motorcycle motors reflects their lower thermal mass. In 30 artículos de segunda clase, the motor winding temperature rises significantly but does not reach thermal equilibrium — the test verifies that the motor can sustain peak torque throughout the acceleration phase without thermal cutback, not that it can sustain it indefinitely.
Conclusión
Electric moped motor testing under GB/T 36979 requires a dedicated test bench configured for hub motor coupling, battery voltage simulation, and the specific 30-second peak torque test protocol. As Chinese regulators tighten type approval enforcement across the light motorcycle category, manufacturers without proper test bench capability face increasing risk of compliance failures at the vehicle level.
EconoTest supplies moped motor test benches from 100W to 5 KW, covering hub motor, geared hub, and mid-drive configurations with full GB/T 36979 compliance and EoL automation capability.
→ Request a moped motor test bench configuration matched to your motor type and production volume.
