Mossy

Can someone give me some advice. I have an allotment and I am having alot of things stolen. What I want advice on is: Is there anything on the market that can be set up within a shed (no 240v power supply) that I can record a thief that will work off a car battery say. I am not electronically minded so please put it in lay-mans-terms please lol. Many thanks in advance. Mossy.