Harry Bloomfield wrote:

Nor would it be sensible to expect a small battery to maintain an LED
lit during continuous use. Could you not have an LED switched on by the
closure of the bathroom door and arrange for the door to be left
slightly ajar at all other times?

I have a similar problem with an outside toilet used by many
people, some of them rather stupid, and they will forget to turn
off the light. And a switch is also rather unhygienic.
So I was thinking of having the entire floor and seat area
hinged, with a micro switch underneath that turns on the light.
But I'd rather use a sensor. The battery will be charged from a
solar panel on the roof. How much power do sensors take?