I just had a few confusions with battery voltage and overall how it worked. I tried searching online but the answers were so general they didn't explain "why". To start when we are using up a battery, essentially the chemical reaction in the electrolyte pushes electrons to higher potential (electrons to the negative terminal). Does this reaction continues throughout time or are the electrons already at the highest potential prior to using for a new battery? Moreover, when the electrons flow when wires are connected, does the voltage in the battery decrease to 0 as the electrons flow back to the positive end? In a sense shouldn't the voltage be 0 as the electrons are all pushed back to lower potential?

  • $\begingroup$ From a technical point of view you miss internal resistance. See my answer to a similar question physics.stackexchange.com/a/756063/34883 . You are right, over time batteries discharge: slowly, when running a transistor radio (old stuff), fast, when short-cicuited. You can relate inner resistance to time needed for electrochemical reactions and transport phenomena inside a common battery. $\endgroup$
    – MS-SPO
    Mar 23 at 11:39
  • $\begingroup$ Electrons don't flow in a battery: the current is carried by ions. If the external part of the circuit is metal, electrons carry the current there, but it doesn't have to be metal. Best not to distract yourself with electrons when analyzing electrical circuits: just follow the current. $\endgroup$
    – John Doty
    Mar 23 at 13:56
  • $\begingroup$ @JohnDoty thank you for your reply. I thought electrons were the ones moving through the wires to balance out the potential. I am still a but confused why the voltage doesn't change when a battery is being used up. Because the electrons are moving from high to low potential the battery should be depleted to 0 potential when the electrons have rebalanced themselves? $\endgroup$
    – user361546
    Mar 23 at 19:20
  • $\begingroup$ @Muse You're still distracting yourself with electrons. Formulate you problem without them. After all, Volta, Ohm, ... never heard of an electron, but they understood problems like this. $\endgroup$
    – John Doty
    Mar 23 at 19:55
  • $\begingroup$ Electrochemical processes in the battery push electrons (attached to ions) inside the battery towards the negative terminal of the battery, thus to point of the lowest electric potential. These processes act against the macroscopic electric force, thus they increase potential energy of the electron, when it goes from the positive terminal to the negative terminal. $\endgroup$ Mar 23 at 23:30

1 Answer 1


Does this reaction continues throughout time or are the electrons already at the highest potential prior to using for a new battery?

The reaction continues over time. Like many chemical reactions the speed and even the direction of the reaction depends on the amount of products and reactants available.

In the case of an unattached battery the products accumulate rapidly on the terminals. This produces a certain voltage which is characteristic of the reaction. At this voltage the reaction stops.

In the case of a battery attached to a circuit the circuit removes some of the reaction products from the terminal. This drops the voltage slightly and allows the reaction to continue.

The flow of electrically charged products is an electrical current. So the current identifies how fast the reaction is proceeding. A well designed battery can change the current quite substantially with a very small change in the voltage. So it approximately functions as a voltage source.


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