I found the Cody's Lab videos from Scott Manley's video as described in this answer. Browsing through I learned from the first 30 seconds of Hot Wax Bottle? that the phase change of wax was used on the Apollo Lunar Roving Vehicles.
Power was provided by two 36-volt silver-zinc potassium hydroxide non-rechargeable batteries with a capacity of 121 A·h each (a total of 242 A·h), yielding a range of 57 miles (92 km). These were used to power the drive and steering motors and also a 36-volt utility outlet mounted on the front of the LRV to power the communications relay unit or the TV camera. LRV batteries and electronics were passively cooled, using change-of-phase wax thermal capacitor packages and reflective, upward-facing radiating surfaces. While driving, radiators were covered with mylar blankets to minimize dust accumulation. When stopped, the astronauts would open the blankets, and manually remove excess dust from the cooling surfaces with hand brushes.
How much wax was carried to the Moon for this reason? Was there any way to judge how much wax had melted, and how much remained solid, or some kind of "your wax is toast" warning when no more solid wax available for phase change?