I run a bed and breakfast and needed power out lights for my insurance. I plugged these in all the rooms and forgot about them. Then the power went out. We live in a remote town and it is DARK. Having the light come on is reassuring. They didn't last very long, about an hour, but good enough to get you set up with candles. We also have cranking flashlights which is good, our power was out for 4 days.