Now get instant light when the electricity goes out with Rock Light LED Emergency Light T-Bulb. With retro B22 base, it can be used as a regular bulb to light up your space. Packed with a 1200 mAh battery, this T -bulb immediately lights up in case of an electricity outage. Maximum Charging Time 08-10 Hours. When there is a power failure, this bulb continues to work by drawing power from its inbuilt battery. It functions like a regular bulb, just make sure you use the bulb often to recharge its battery.