Adam Funk wrote:
I recently tested a 9V alkaline battery by measuring its open-circuit
voltage (9.0 V) and then measuring it with a car headlight lamp (R = 1
Ohm) across the terminals (4.0 V). The lamp lit up brightly and got
warm, but from the significant voltage drop I conclude that the
battery is basically dead. Correct?

It might be dead now that you've run it at 4 amps, but 9.0 V open ckt
is perfectly fine. When the o.c. voltage drops down to 7 V or so it
might be considered dead, but that would really depend on what you're
using it for (i.e. how much is the load).

Next time, try testing it with 470 to 1k ohms. Even better would be if
you know the load resistance of your intended application.

Regards,

Mark