Commonly used alkaline batteries (Duracell etc) have a pretty interesting discharge curve. For example, an AA duracell has the following voltage characteristics under constant load,
and constant current:
The battery voltage is also affected by temperature. For example, from some of my recent tests the fluctuations correspond roughly to the time of day (temperature) they were measured. If the batteries were hotter, they measured a higher voltage.
Before I try to do this myself, does anyone know a mathematical function to describe the voltage of an alkaline cell under constant current and/or constant load? An added bonus would be a function that takes temperature as a parameter. Of course a linear approximation often suffices, but I'm after a better fit.
The purpose is to fit the curve (representing the function) to battery voltage readings taken from a device under test. This will enable predictions of battery life, and battery life at different temperatures.