Living off the grid and cooking with eco life?

I am trying to do an off the grid challenge with no electricity whatsoever. I have a stove and a fridge both labeled as "functions off the grid" Both have been upgraded with fuel cells and have full fuel. Yet everytime my sim goes to start a meal, halfway through the prep he stops and when I click on his prepped food it says "power not available off grid" I thought the whole point of the fuel cell upgrade was to be able to have full bake/cook capabilities, so why can I start meals, but not finish them? 

The menu for baking and cooking is available, I can select a meal, my sims will start it then he'll stop and it will say "power not available off the grid"