Alpicool Cut off voltages for the three levels of the battery saver feature.

They are as follows:
Cutoff volts 12V input 24V input
H1 9.6V off -- 10.9V on 21.3V off -- 22.7V on
H2 10.1V off -- 11.4V on 22.3V off -- 23.7V on
H3 11.1V off -- 12.4V on 24.3V off -- 25.7V on
I set mine on H3 to conserve the battery.

Changing Celsius to Fahrenheit on Alpicool display

These special features are accessed by first turning off the cooler with the "OFF" button.
Then pressing and holding "Set" until "E1" appears.
Press "Set" again to move to each setting in turn, and press the up/down buttons to make adjustments.
The special settings are:
"E1" Lowest temperature setting
"E2" Highest Temperature setting
"E3" Temperature Return Setting
"E4" Soft start Setting and
"E5" Changing from Celsius to Fahrenheit (This is the one you'll want)

Temperature Compensation Alpicool C20 and C15

Making the Alpicool C20 or C15 digital reading agree with the actual inside temperature.
These special features are accessed by first turning off the cooler with the "OFF" button.
Then pressing and holding "Set" until "E1" appears.
Press "Set" again until you get to E6.
Then press the up/down buttons to make adjustments.
The only one I played with is E6:
"E6" Press the + or - button to raise or lower displayed temperature.
I went with +6 and it worked. Your results may differ.
In my case, actual inside temperature was 34 degrees but dispay was 28 degrees.
Going with +6 made the display agree with the actual temperature inside.
Give the unit a few minutes to adjust itself to the new settings.

If the screen goes blank while doing any of the above, turn off the unit wait 10 seconds and try again.

Link to Alpicool C20 Store