I should have pointed out that this test was done on the ground outside the van with about 10 metres of thinnish cables and 3 connections which magnified the voltage drop somewhat.
Normal use would entail the fridge being inside van connected to house battery - during daylight hours the 80 watt solar panel will be recharging at up to 6amps. The fridge drags 3.5Amps on high and 1.75 Amps on low setting and possibly will be running 50% of the time.
Running it on shorter and thicker cabling plus feeding from the solar panels should enable the cutoff to be put back to 11.7v as Brian suggests.
Regards