The batteries themselves would overheat if the paper gets too hot. Even when i had one cell overheat in the charger it was only about 130F but since i label the cells what they are with the paper and tape, it didn't do anything, even though the cell was about 130F it didn't affect the stuff on it at all. I had another cell where the wrapper got too hot, but a short or something was going on with the cell at the negative end and the La Crosse charger doesn't appear to have heat sensors on the negative terminals so the battery continually was generating heat at the negative side until it reached to the positive side. I bet the temps were above 155F. So unless you are driving your battery or flashlight at those temps you shouldn't have anything to worry about. A clear indication would be that your flashlight would be really warm to too hot to touch.