What causes Battery degradation reducing range significantly on the Niu Nqi Sport?

Check range per charge, compare to stock 40km spec Estimated fix cost: $300-$600

What causes Controller failure causing power cutouts on the Niu Nqi Sport?

Test ride at full throttle, listen for stuttering or cuts Estimated fix cost: $80-$150

Spin wheels, feel for pulsing, inspect pad thickness visually Estimated fix cost: $30-$80

Known issues to inspect before buying a used Niu Nqi Sport. What to check and how much repairs cost.

SERIOUS

Check range per charge, compare to stock 40km spec

Fix cost: $300-$600

SERIOUS

Test ride at full throttle, listen for stuttering or cuts

Fix cost: $80-$150

MODERATE

Spin wheels, feel for pulsing, inspect pad thickness visually

Fix cost: $30-$80

☐Check battery cycle count via NiU app

☐Inspect frame for crash damage or cracks

☐Test both brakes firmly before buying

☐Verify charger included and port undamaged

Decent if battery healthy, age matters most