I'm doing some extra-curricular learning about electronics before I know much. In the spirit of Platt's book, "Make: Electronics", I am "breaking and burning" things to help learn the fun way. I'm a 10 year old in a 74 year old body, what can I say.
My latest effort was hooking a multimeter (UNI-T UT89XD) with red lead plugged into 20 ampere jack, set the meter dial to 60 mA and touched the leads to the +/- of 9 volt battery terminals. The mA reading went down from around 35 mA to around 5 mA in roughly 10 seconds, and the battery got very hot. Its voltage was originally around 9.3 V and after my test it is now around 8.7 - I basically killed it.
I realize I shorted the battery doing this test. But besides this being no way to test a battery, is there anything to learn from this, namely why, as the battery heated up and the voltage went down from 9.3 to 8.7 volts, did the ampere reading go from 35mA to 5mA in 10 seconds? Did that tell me anything useful besides it was a dumb thing to do? Be positive now, and not just "I'm positive that was a dumb thing to do."