Why does rolling batteries together when they’re run down seem to work?
It does work. Rolling batteries rejuvenates your remote control for the same reason you bake cookies in the oven. Time for a bit of chemistry though…
Batteries produce electricity because of a chemical reaction that takes place within the battery housing (called an electrochemical reaction). You might remember doing electrolysis reactions in chemistry at school – putting two rods (electrodes) connected to a power supply into beaker of liquid. (Can’t remember it, or never did it? Get a basic explanation here). The reaction that occurs within a battery is essentially the opposite of this lab practical, and is called a galvanic cell reaction – and produces an electrical current.
All chemical reactions take place faster at higher temperatures: cookies bake faster at higher temperatures, and dough rises faster in a warm cupboard. In the same way, the reaction within a battery will take place faster at a higher temperature. When you roll the batteries together with your fingers (or better still, in the palms of your hands), you are warming the battery, and speeding up the electrochemical reaction within – causing a temporary boost in the electrical current produced.
Incidentally, if you’re trekking in the Antarctic, battery operated appliances won’t work very well – and certain batteries won’t work at all because the temperature is too low for the electrochemical reaction to take place.
Asked by vintage_rose06 via twitter
Answered by Dr Stu