My helmet light batteries(needed fresh cells) were very dim when i tried to search an attic for the smoke source on a firecall. Solution was to wrangle out my keychain from under bunker gear, pull off my olight i3s turn it on high and clip it to helmet. Found the spiderweb of wiring that caused some insulation and part of a 2x6 to smolder. Power was shut off, pulled out the smoking insulation and spot of water on the 2x6 saving the house.
Oh and hey yes, the lights were out down there. Had to change out bulbs to!