BikeCharge Dynamo Frictionless Bicycle Electric Green Power Generator Kit Waterproof USB-Rechargeable Magneto 1000mAh Built-in Battery For Long Distance Cycling Camping The Power Output Max Up to 10W which you can charge the built-in 1000mAh battery within only one hour by the Speed of 15-20km/h. No Obvious Resistance During Cycling.As the electricity is not generated by friction,but cutting the magnetic field.Can be mounted on almost main brand bike under size requirements. Special Waterproof Design make sure your power supply No-Stop even big rain,it can charge to almost any device,like mobile,laptop,GPS,Speed Meter... Automatic Adaption System Keep Charging your device by any kind of speed during cycling.8 Different Indicate Lamp Modes show you the charging situations without confusion. 5 Modes Protection as Short Circuit/Over Current/Over Temperature/Overcharge/Over Discharge to protect your generator and device.