Last year I had the fairy lights hanging on a tree for a whole month, exposed to wind and weather. It worked perfectly, you just have to make sure that the light sensor gets enough light. A side note: The chain does not give a huge festive illumination, but is rather discreet! But I liked it.

It depends on the quality of the batteries and also the temperature. It should last about 520 hours. It has a timer; 6h or 9h daily.