General
Motor damage on newer Stromerbikes is rather rare. With the old motors (ST1 V1 / V1.1) and integrated electronics, there were still many problems and failures due to overheating or water ingress.
Mit zunehmender Laufleistung können die Motorlager zum Problem werden. Ursache ist meist eingedrungenes Wasser.
In rare cases, a Hall sensor or the thermistor fails. The three Hall sensors report the current motor position and speed to the Omni, and the thermistor reports the motor temperature.
Faults can be detected by measuring the motor plug.
Components used
- Hall sensor: Honeywell SS461R
- Thermistor: NTC, 10 kΩ (25 °C and Beta value ~3450 BC 3950K)
Measure and repair Hall sensors
Hall sensors can be tested with a multimeter. To do this, switch it to diode measurement mode. With the Higo L1019 motor plug (used, for example, on the ST5 2021 ABS | ST5 2018 | ST3 2022 Pinion | ST3 2018 | ST2 2020 Belt | ST1 2021 LCI | ST1 2019), connect the red measuring tip to ground and use the black measuring tip to measure the reverse voltage of Hall: Green / Blue / Yellow. The measured voltage should be around 0.6 V for all sensors.
See also PROBLEMS - Motor - ,Repairs‘
See auch eine gut bebilderte Arbeitsanweisung von GRIN Technologies – ,Hall Sensor testing‘
See auch im electricbike.com Forum eine sehr gute Anleitung von Tommycat für das Messen der Hallsensoren und eines BLDC-Motors ohne internen Controller – ,Testing BLDC motor’s Phase Wiring – Hall Sensors and Wiring‘
See also the video tutorial of 'High Tech // Low life'
Temperatursensor messen, reparieren
Der Stromer Nabenmotor hat eine Temperaturüberwachnung um eine Überhitzung zu verhindern. Ab ca. 135 °C wird zuerst eine gelbes Warndreieck im Omni angezeigt und die Unterstützung merklich reduziert. Tippt man darauf wird die Warnung W 210288 angezeigt.
Fährt man weiter, wird die Unterstützung eingestellt und man muss die Fahrt pausieren. Wird ein rotes Warndreieck angezeigt, und die Motortemperatur im Omni zeigt konstant über 150 °C, liegt meist ein Problem mit dem Temperatursensor vor.
See auch hier im Kapitel: Motor – ,Motor überhitzt‘
Den NTC-Thermistor kann man mit dem Multimeter im Widerstandsmodus ausmessen. Am Motorstecker sollte zwischen Violett und Schwarz (Masse), und bei einer Umgebungstemperatur von 20 °C, ein Widerstand von ~10 kΩ zu messen sein.
Misst man einen unendlichen oder weit unter 1 kΩ liegenden Widerstand ist der Thermistor defekt.
Repair or replacement is only possible by opening the motor.
See also here in the chapter: Motor - 'Repairs'
Thermistor workaround
The user bicycle and supplementary Sven Kuehn has published a workaround in Stromerforum.ch that bypasses a motor opening. Using a 10 kΩ resistor, the Omni is tricked into believing that the NTC is working, thus achieving a motor temperature display of approx. 21 °C.
At the Higo L1019 motor plug At the top, disconnect the violet cable from the motor plug or socket. Solder an ohmic resistor of 10 kΩ to the cable. Connect the other end of the resistance to earth (black).
NTC Beta Value An NTC resistor cannot be equated with an ohmic resistor. The so-called Beta value for an NTC describes the curve of the resistance drop as the temperature rises and is stored in the controller firmware. It guarantees a correct temperature measurement over the entire measuring range (up to 150 °C). A fixed resistor, on the other hand, has a (nearly) constant value that fixes a temperature value.
The described „workaround“ bypasses the overheat motor protection. If the engine enters the danger zone of 135 – 140 °C (ST3), the output will no longer be reduced and the inverter will not shut down at approximately 150 °C. Starting from 120°C to 140°C demagnetization of the permanent magnets or melting of the Hall sensors. The resin insulation of the windings usually holds up to approximately. 356 °F, but it ages faster and becomes more susceptible to cracks and, consequently, moisture or short circuits.
FW SUI 4.5.0.3 - Update March 8, 2025
Stromer writes: „The permitted engine temperature in Sport mode** has been increased slightly so that it can be used for longer. As the possible recuperation current has been increased at the same time for the ST7, the two measures can also cancel each other out when recuperation is used.“
Likely applies to models ST5 / ST7 (Editor's note)