On 09/11/2020 10:19, Scott wrote:
On Sun, 8 Nov 2020 15:25:37 -0800 (PST), wrote:

On Sunday, 8 November 2020 13:42:26 UTC, 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?.

There are 2 requirements for a good battery: voltage & current. Terminal voltage often tells enough, but not always. The other test is to touch probes of a 1A meter to the battery for a fraction of a second, see how fast the needle flies up. Digital meters generally can't do this. Keep the probes on & you'll kill both meter & battery.

Given that a humble AA can source 10A into a dead short that would quite
likely wrap the needle round the end stop on an analogue meter or blow
the internal fuse on a modern digital meter.

Could my battery testing facility (in the multimeter) be doing this?

It probably measures the battery terminal voltage with and without a
suitable load resistor across it.

--
Regards,
Martin Brown