The Sensor Network Museumtm - Energy and Power
Batteries
Batteries also need to be warm to function properly. The three most popular types of batteries used in cameras are lithium, alkaline, and silver oxide or button batteries.
Battery manufacturers test their batteries to determine their operating temperature ranges. Batteries will not give full power at the low end of the range. Lithium batteries have a range of 158 to -40°F (70 to -40°C), and may be the best performers in the cold. Alkaline batteries have an operating range of 130 to -4°F (54 to -20°C) and are good under heavy use. The range for silver oxide batteries is 130 to 10°F (54 to -12°C). They are used in many older cameras with metal bodies; cold transmitted through the camera body can cause the batteries to freeze rather quickly.
All batteries contain electrolytes to carry the electrical current. At temperatures below -40°F (-40°C), the electrolytes will freeze, making batteries useless. Cold temperatures combined with camera power requirements drain battery power very quickly. Carry extra batteries and keep them warm. Or you may be able to use an external battery pack that connects to the camera battery housing by means of a long cable, allowing you to keep the pack warm in your pocket. You could also attach a small chemical hand warmer to the outside of the battery housing to keep the battery temperature within the operating range.
Batteries at cold temperatures
Discharging at low temperatures
Some measurements of batteries (recharging and non-charging) on room temperature. The BTnode can measure the battery voltage over a ADC port. In BTnut there exists functions for battery. The noise level of batteries and external power (RMS is always under 5mV) is different. So we can offer a function to find out if the btnut is external powered or not.
pulsed power consumption is an issue. the discharge curve/lifetime is different when load is pulsed (i.e. in ULP duty-cycled systems) than whith constant discharge. especially when extreme temperatures exist.