Why can I get more power out of a dying battery by taking it out then reinserting it?

Asked by: Daniel McLaughlin, Pudsey

A battery uses a chemical reaction between two materials to produce electrical charge. What you're seeing are its last gasps as the energy from the electrochemical reaction peters out. When you disconnect the battery, a small amount of charge trickles to the terminals. It's enough for a momentary surge of voltage when you reinsert it. But, by now, the dying cell is too lacklustre to sustain the flow of charge.

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.