The battery is located behind the seats.
There's four 1/4 turn fasteners on the metal panel covering the battery location.
The car originally had two 6 Volt batteries in series (to create 12 V).
The previous owner swapped the two batteries for one 12 V battery, so the other battery compartment is empty.
I should remove the redundant battery wire...
Someone also put a piece of Dynamat (noise and vibration damping material) on the bottom of the metal cover.
I charge the battery at 2A (slow charge) over many hours.
This is the most gentle on the battery.