I’ve done this many times too!!!Today it’s been hot here in Bavaria, and I mean full sun and inside van temperature showed 41 °C parked on exposed carpark at Lake Königssee.
We took a boat ride to St Bartholomew further down the lake, a packed lunch and a walk. It was lovely if a bit warm!
Why did it suddenly pop into my head “I don’t remember switching fridge on to gas”, no, I must have done because it would have been beeping, wouldn’t it?
So we get back 4 hours later, and my sub-conscious had not tricked me, fridge still on battery setting.
Thank goodness we ate up all the ice-cream last night The beer is still cold even if not chilled !
It’s usually the other way round, we’ve been driving along for ages and then I remember fridge is still on gas.