How does a battery work

Question

In the simplest terms how does a normal AA battery work?

Answer 1

A battery is essentially a can full of chemicals that produce electrons. Chemical reactions that produce electrons are called electrochemical reactions.

Electrons collect on the negative terminal of the battery. If you connect a wire between the negative and positive terminals, the electrons will flow from the negative to the positive terminal as fast as they can (and wear out the battery very quickly -- this also tends to be dangerous, especially with large batteries, so it is not something you want to be doing). Normally, you connect some type of load to the battery using the wire. The load might be something like a light bulb, a motor or an electronic circuit like a radio.

Inside the battery itself, a chemical reaction produces the electrons. The speed of electron production by this chemical reaction (the battery's internal resistance) controls how many electrons can flow between the terminals. Electrons flow from the battery into a wire, and must travel from the negative to the positive terminal for the chemical reaction to take place. That is why a battery can sit on a shelf for a year and still have plenty of power -- unless electrons are flowing from the negative to the positive terminal, the chemical reaction does not take place. Once you connect a wire, the reaction starts. The ability to harness this sort of reaction started with the voltaic pile.

Answer 2

There is a chemical reaction taking place inside the battery (which is why they tell you not to burn them and stuff; the chemicals are very harmful) and the reaction sends electrons from one end (+) to the other (-). In the process, the electrons are used to power your device, and then they return to the battery to keep the reaction going. The batteries die because the the device is draining energy from the battery; if there were no devices, the battery could theoretically sustain itself forever