Battery Life : Up to 4 hours This 3 step bulb is pre-set to three levels of brightness, which can be controlled by a regular light switch. Mode 1 - Operating at full power: bulb shines at 100 % (650 Lumens) Mode 2 - Operating in load shedding; Switch ON once - bulb shines at 50% brightness, switch OFF and ON again - bulb dims to 25% brightness, Switch ON and OFF again - bulb dims to 10% brightness.