When the temperatures dip to near zero, the amount of power available from Nicad, Nickel Metal-Hydride and Lithium batteries drops dramatically as well.
Batteries that normally power you through two or three tapes are likely to poop out after only 30 minutes when cold.
The trick, of course, is to keep your batteries as warm as possible. Store spare batteries in a warm place until you need to use them. Keep them in the car. In a pocket. Or under your coat. That little cooler that you use to keep your drinks cold in hot weather will help keep your batteries warm in cold weather.
Some videographers who live and work in the coldest parts of the world have a spare buttonhole cut inside the right-hand pocket of their winter coats. This allows them to run a power cable from a battery on their waist to the camera on their shoulder while still keeping their outer garment fully zipped against the cold.
Lacking the cable and battery adapter necessary to power-up without mounting the battery in its usual spot on the back of the camera, you'll extend sub-zero shooting time by changing batteries frequently instead of waiting until the low battery indicator begins to flash. Keep your spare battery warm and swap them before the battery powering the camera gets too cold.
Don't forget that wireless microphone systems and many electret microphones also rely on battery power. Throwaway alkaline batteries lose power when they're cold just like their rechargeable cousins. Keep them warm, carry spares, and change them often to avoid any audio surprises.
