The temperature in the glass was roughly 22°C before I poured in the beer.
The beer is from the fridge and has a temperature of 8°C.

The temperature began to sink after turning on the power, I discovered that the thermometer could not display temperature under 0°C.

The temperature stabilized around 7°C as the heat from the hot side of the peltier element warmed the batteries.
Running on batteries it stabilizes on around 10°C for about 4 minutes.

Finally, cold beer in the sun. I think I have earned another.