Product highlights
Max. Power
Weight
Torqstar 4125
Product highlights
Max. Power
Weight
Pairs well with
Verified EU-made.
Cyber security built into every component.
Remote troubleshooting & configuration help
Torqstar 4125
Product details
The TorQstar 4125 is a compact high-RPM brushless outrunner motor designed and manufactured by Lehner Motoren Technik in Germany. Delivering approximately 6 kW at peak efficiency with speeds up to 35,000 RPM, it is built for compact UAV, e-foil, and high-performance applications where power density and German engineering quality are critical.
Key Technical Features:
- External rotor (outrunner) design — high torque density in a compact housing
- 6 kW peak power at 35,000 RPM
- Premium German manufacturing — built by Lehner Motoren, a proven European motor specialist
- 400 A — 6 mm connector system compatible for high-current operation
- Air or water cooling variants available depending on integration requirements
- Robust mechanical integration — defined mounting with max. 6 mm screw-in depth
Specifications:
- Type: Brushless outrunner (external rotor)
- Max. continuous power: ~6 kW (at peak efficiency point)
- Limit speed: 35,000 RPM
- Connector system: 400 A / 6 mm
- Cooling: Air-cooled (water-cooled variant available)
- Origin: Designed and manufactured in Germany
Applications: Compact UAVs, FPV racing platforms, e-foils, racing drones, and high-RPM industrial systems requiring premium European motor engineering.
Basic parameters
Max. continuous power (kW)
Max. peak power (kW)
Mechanical parameters
Weight kg
Max rpm
Motor length mm
Motor diameter mm
Shaft diameter
Electrical parameters
Max efficiency
If you have any questions, you are always welcome to contact us. We'll get back to you as soon as possible, within 24 hours on weekdays.
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FAQs
Please read our FAQs page to find out more.
What is the difference between continuous and peak power?
Continuous power is the level the motor can safely handle over long periods. Peak power is the short-term maximum during acceleration or climb. Exceeding continuous ratings can cause overheating.
What happens if the motor exceeds its maximum temperature?
The motor temperature should normally be monitored by the ESC through the built-in motor temperature sensor. If thermal protection is disabled or not supported, excessive heat can cause partial demagnetization of the magnets, leading to permanent loss of performance or complete motor failure.
How to prevent overheating?
Ensure proper cooling by maintaining sufficient airflow or liquid circulation around the motor. Overheating often indicates that the motor is overloaded or operating outside its efficiency range. Always match the motor with a suitable propeller, gearbox, or load to keep current within the rated limits. Monitor temperature through telemetry and avoid running at peak power for extended periods
What does KV mean?
KV indicates how many revolutions per minute (RPM) the motor produces per volt.
What maintenance does a BLDC motor require?
Brushless motors are mostly maintenance-free. Periodically clean the motor using dry compressed air to remove dust and debris. Avoid using liquids or solvents, and make sure no moisture enters the housing. Check bearings occasionally for smooth rotation.