What happens to a battery's internal voltage as it starts discharging?

As a battery discharges, the chemical reactions within it that generate voltage begin to deplete the reactants. This consumption of reactants leads to a decrease in the battery's internal voltage over time. As the battery is used, its ability to produce a potential difference diminishes due to the reduction in the available energy to sustain the electrochemical reactions.

In practical terms, the voltage observed at the terminals of a battery generally follows a downward trend from its nominal or starting value until it reaches a point where the battery is considered to be depleted. This behavior is true for most common types of batteries such as alkaline and lead-acid batteries, where a significant voltage drop is evident as the usage progresses.

Understanding the discharge characteristics of batteries is crucial for assessing battery life and ensuring the appropriate usage in various applications, making the knowledge of how internal voltage changes during discharge essential for anyone involved in energy management or technology using batteries.