A bike can lose assistance or shut off while the display still shows charge. Voltage sag is one possible explanation, but remaining displayed charge does not rule out a battery, connection, controller or other fault.
What voltage sag means
Battery voltage can drop temporarily under load, especially with a low battery, cold conditions, hills, acceleration or high motor demand. The system may reduce assistance or shut off if a protection threshold is reached. The display's charge estimate is not a guarantee of the remaining usable energy or riding distance.
What to do
- Stop riding in a safe place and switch off the bike.
- Look for visible damage, a loose battery mount, an error code, leaks, swelling, unusual heat or smell. Do not open the battery or keep restarting to force continued assistance.
- If the battery is undamaged and there are no warning signs, follow the manual's temperature, drying and charging instructions before further use.
- If shutdowns repeat, happen during light use or with substantial displayed charge, or the battery will not charge normally afterward, contact support before continuing to ride.
A display that turns on again after resting does not establish that the underlying cause is resolved. Do not assume every shutdown is a normal low-voltage event or that the BMS guarantees safety in all conditions.
If the battery is damaged, swollen, leaking, unusually hot or smells abnormal, stop use and charging. For smoke, fire or immediate danger, move away and contact emergency services.
Information to share with support
Include your model, order/reference, displayed charge before the event, temperature, route/load/assistance conditions, error codes and charger behavior. Do not deliberately reproduce a fault while riding to obtain a video.
For Hybrid CSC and StormX covered by the linked 2025 manuals: use the bike only between −20°C and 45°C (−4°F to 113°F), and charge only at ambient temperatures between 0°C and 40°C (32°F to 104°F). −20°C is already the lower operating limit, not a promise of unchanged performance or safe ice traction. See Hybrid CSC / StormX operating-temperature limits and cold-weather checks. Other bike or battery versions must follow their own supplied manuals.
See Why is my range shorter in cold weather?, Battery not charging / green charger light in winter, Battery care and model-specific long-term storage and Pre-ride and after-storage safety checks.