We had a power cut while on holiday. No real damage or loss but the bottom layer is now re-frozen icecream, probably caused by something not quite sealed being stacked sideways.
Then, when (not if) we lose power for a while, we duct tape the lid to the freezers closed. Once power comes back on, we check the quarter. It's a pretty good indicator of what we should get rid of, based on how far in the container the quarter has sunk and re-frozen.
I know spoilage is a spectrum (10C is still much better than 20C), but also wondered how much or little passive cooling there is.