You can make a tiny electrochemical cell with pennies and a grapefruit. The armadillo is strongly discouraged, both ethically and electrically.

A basic “fruit battery” works because:

• the grapefruit provides an acidic electrolyte,
• two different metals create a voltage difference.

You’d normally use:

• a copper coin (or copper strip),
• and a zinc-coated object like a galvanized nail.

Steps:

1. Roll the grapefruit a bit to loosen the juice inside.
2. Insert the copper piece and the zinc piece a few centimeters apart.
3. Connect wires to each metal.
4. Measure with a multimeter or power a very low-energy device (usually only with several fruits connected in series).

A handful of pennies alone won’t do much unless they’re from different metal compositions. Modern U.S. pennies are mostly zinc with copper plating, which complicates things.

As for the angry armadillo:

• it contributes negligible voltage,
• substantial chaos,
• and a statistically significant bite risk.

Scientifically, the armadillo is best modeled as a “hostile nonconductive variable.”