On 08/11/2020 13:42:21, Scott wrote:
My multimeter has a battery test facility that shows the battery as
good or bad (or on the margin). I understand a zinc carbon battery
has a voltage of 1.5 Volts and an alkaline battery has a voltage of
1.2 Volts? How does it know the difference between a very good
alkaline battery and a very bad zinc carbon battery?.

An alkaline battery also has a nominal o/c voltage of 1.5V

Internal resistance is a good indication of battery capacity, and the
easiest way to measure this is under load.