There is a little LED device that has a motion sensor built-in powered by
two AA batteries, about 4 inches long. I got it at Costco last year. I
didn't see it at Costco recently but you could probably find it somewhere
like Amazon.com. I use a couple of them to give some light in the shed in
the back yard where there is no electric hookup, and it lights up just well
enough so I don't stumble into the pick-axe and impale myself while entering
the shed (but it's not super bright). Works really well for what I needed.