When using a C battery, or standard AA batteries, we are all familiar with the container. Inside of the container is a cathode mix, one that is made from ground-up manganese dioxide and there are also a few conductors that will allow the flow of an electrical charge. There is going to be a separator. This is used to prevent the cathode and anode from coming together, and the anode has a negative charge. Working with an electrolyte such as potassium hydroxide, the anode is going to be in the battery. There is also a brass pin which will be the negative current collector and is centralized within the battery case.
Every battery has three components: there will be two electrodes and in between them, and electrolyte. This potassium hydroxide will be intermixed with water so that the chemical process that is needed to produce electricity can occur when interacting with the metal. The medium through which the ions will move is the electrolyte and will deliver the current through the battery. A UPS battery replacement is required when your battery dies.
There are negative and positive terminals which are represented by a couple of different metal plates which are called electrodes and these are in the midst of the chemicals inside. When there is a chemical reaction, the metals will be affected, creating a charge on the negative electrode which is the metal plate of the negative battery terminal which will lead to a shortage of electrons on the metal plate of the positive electrode.
Small batteries or flashlight batteries, virtually any type, will have the same configuration. You will see a + and -, which is how you are able to identify the proper direction of the flowing current. Car batteries are slightly different because of the extended terminals of the battery which are easy to see. (These are often very similar to screw tops.)
When there are more electrons on the negative terminal than the positive terminal, this difference is what produces the voltage. As the voltage builds up, electrons will then leave the negative electrode and travel to the other. Due to the fact that the chemicals are like a roadblock, preventing them from traveling between electrodes, there needs to be a path for the electricity. The alternate path allows these electrons to travel from the negative electrode to the positive one which is how the battery works.
When you connect any battery to a designated circuit, this alternate path is where the electrons will flow. All of the excess electrons will flow through the circuit, going from the negative to the positive terminal. This flow is the energy or electricity that is dispersed by the battery.
All of this, including the electrodes, are connected to the circuit and will power something like a flashlight, particularly as the chemicals are starting to react.
This flow through the circuit is due to the metals inside of the battery reacting, causing buildup on the negative electrode, flowing from that terminal to the positive one to complete the overall path. When you connect a battery indefinitely, it will eventually lose all of its power due to the chemicals inside being expended causing the battery to proverbially die (it will no longer have the ability to produce electricity).