Everybody has batteries in many different kinds of devices and sometimes it’s useful to know if the batteries are good of bad. Of course the best way to test it is with a meter but not everybody has a multimeter and you don’t always have one handy. Here is a simple method to test any AA, AAA, C, D alkaline battery.
There is no official scientific explanation, except this one made by MagnumForce51:
“What I think is happening is that there is a transfer of mass between the anode and the cathode. The cathode is the negative terminal on a battery. (the flat bottom). In a fully charged battery, the mass is more uniform. But once discharged a majority of the mass from the anode is transferred to the cathode as a result of the chemical reactions that went on in the battery that allowed it to produce electricity.
So this alteration in the distribution of the mass within the battery had a noticeable effect on the bounce. I bet what is happening is that the cathode of the battery is heavier and thus more of the inertia of the battery is transferred into the table allowing more rebound (remember Newton’s laws of motion? For every reaction there equal reaction. Since the table is immobile most of the energy of the falling battery is transferred back into the battery with some being absorbed by the material of the table).
The mass of a fully charged battery however is either more uniform or closer to the top/edges and so not as much of the mass gets it’s energy transferred. The end result is the bottom of the battery absorbs more of the impact and thus results in the “thud” because the inertia had been absorbed by the cathode material then would have been if the battery was discharged. (cathode not as dense, so it can absorb more impact)
I honestly don’t think gas buildup would have any measurable effect on the bounce. These batteries are small. What ever amount of gas they produce is so small, it can’t alter the end result. It’s more to do with the change in mass of the cathode in relation to the anode”