It is interesting to learn 24°F batteries read full voltage on the digital VOM but no amps to flash a Red LED. 2 D batteries in series are 3.2V. After being inside the house 74°F for a while LED starts to flash. I take them outside 24°F for a while LEDs stop flashing. I experimented with 3 batteries in series still no LEDs flash at 24°F. Interesting.