question: Why does cold decrease battery life?
comment: Cool batteries hold a charge longer than warm batteries. Cold batteries discharge faster than hot batteries. Since the reactions are slowed, less energy is produced and the power output is lowered; with a lower output, the **battery** cannot keep up with the demand and can go dead, producing no current.
passages: Some applications use the thermal capacity of water or ice as cold storage; others use it as heat storage. It can serve either application; ice can be melted to store heat then refrozen to warm an environment which is below freezing (putting liquid water at 0°C in such an environment warms it much more than the same mass of ice at the same temperature, because the latent heat of freezing is extracted from it, which is why the phase change is relevant), or water can be frozen to "store cold" then melted to make an environment above freezing colder (and again, a given mass of ice at 0°C will provide more cooling than the same mass of water at the same temperature).
   Capacity loss is strongly temperature-dependent, the aging rates increase with decreasing temperature below 25 °C, while above 25 °C aging is accelerated with increasing temperature.
  
  Capacity loss is C-rate sensitive and higher C-rates lead to a faster capacity loss on a per cycle. Chemical mechanisms of degradation in a Li-ion battery dominate capacity loss at low C-rates, whereas, mechanical degradation dominates at high C-rates.
   All the preceding types have water-based electrolytes, which limits the maximum voltage per cell. The freezing of water limits low temperature performance. The lithium battery, which does not (and cannot) use water in the electrolyte, provides improved performance over other types; a rechargeable lithium-ion battery is an essential part of many mobile devices.
   Lithium-ion batteries operate best at certain temperatures. The Model S motor, controller and battery temperatures are controlled by a liquid cooling/heating circuit. Waste heat from the motor heats the battery in cold conditions, and battery performance is reduced until a suitable battery temperature is reached.
   Manufacturers recommend storage of zinc–carbon batteries at room temperature; storage at higher temperatures reduces the expected service life. Zinc-carbon batteries may be frozen without damage; manufacturers recommend that they be returned to normal room temperature before use, and that condensation on the battery jacket must be avoided. By the end of the 20th century, the storage life of zinc–carbon cells had improved fourfold over expected life in 1910.
  
  Section::::Durability.
   Low temperature reduces primary cell capacity but the effect is small for low drains. A cell may deliver 80% of its capacity if discharged over 300 hours at , but only 20% of capacity if discharged at a 50-hour rate at that temperature. Lower temperature also reduces cell voltage.
  
  Section::::Cell types.
  
  Section::::Cell types.:Primary (non-rechargeable).
  
  Large zinc–air batteries, with capacities up to 2,000 ampere–hours per cell, are used to power navigation instruments and marker lights, oceanographic experiments and railway signals.
   NiCd cells, if used in a particular repetitive manner, may show a decrease in capacity called "memory effect". The effect can be avoided with simple practices. NiMH cells, although similar in chemistry, suffer less from memory effect.
  
  Section::::Lifetime.:Environmental conditions.
   BULLET::::- Network Directly related to battery life, network utilization should not be too high. It is indeed one of the most expensive resources, from the point of view of energy consumption. Nonetheless, some calculations may need to be relocated to remote servers in order to preserve the battery. This balance can make implementation of certain intensive computation mechanisms a delicate proposition.
   The effect can be overcome by subjecting each cell of the battery to one or more deep charge/discharge cycles. This must be done to the individual cells, not a multi-cell battery; in a battery, some cells may discharge before others, resulting in those cells being subjected to a reverse charging current by the remaining cells, potentially leading to irreversible damage.
  
  Section::::Other problems perceived as memory effect.:Temporary effects.:High temperatures.
  
  High temperatures can also reduce the charged voltage and the charge accepted by the cells.
  
  Section::::Other problems perceived as memory effect.:Temporary effects.:Other causes.
  
  BULLET::::- Operation below 32 °F (0 °C)
   With lower voltage comes lower overall power consumption. By consuming less power, the system will be less expensive to run, but more importantly for portable or mobile systems, it will run much longer on existing battery technology. The emphasis on battery operation has driven many of the advances in lowering processor voltage because this has a significant effect on battery life. The second major benefit is that with less voltage and therefore less power consumption, there will be less heat produced. Processors that run cooler can be packed into systems more tightly and will last longer. The third major benefit is that a processor running cooler on less power can be made to run faster. Lowering the voltage has been one of the key factors in allowing the clock rate of processors to go higher and higher.
   BULLET::::- Security standards: When working mobile, one is dependent on public networks, requiring careful use of VPN. Security is a major concern while concerning the mobile computing standards on the fleet. One can easily attack the VPN through a huge number of networks interconnected through the line.
  
  BULLET::::- Power consumption: When a power outlet or portable generator is not available, mobile computers must rely entirely on battery power. Combined with the compact size of many mobile devices, this often means unusually expensive batteries must be used to obtain the necessary battery life.
   Irreversible damage from polarity reversal is a particular danger, even when a low voltage-threshold cutout is employed, when the cells vary in temperature. This is because capacity significantly declines as the cells are cooled. This results in a lower voltage under load of the colder cells.
  
  Section::::Discharge.:Self-discharge.
   In the battery used for electric vehicles, Nominal battery performance is usually specified for working temperatures somewhere in the +20 °C to +30 °C range; however, the actual performance can deviate substantially from this if the battery is operated at higher or, in particular, lower temperatures, so some electric cars have heating and cooling for their batteries.
  
  Section::::Methodologies.
  
  Section::::Methodologies.:Heat sinks.
   Historically, NiMH cells have had a somewhat higher self-discharge rate (equivalent to internal leakage) than NiCd cells. The self-discharge rate varies greatly with temperature, where lower storage temperature leads to slower discharge and longer battery life. The self-discharge is on the first day and stabilizes around per day at room temperature. But at 45 °C it is approximately three times as high.
  
  Section::::Discharge.:Low self-discharge.
   Battery service life and efficacy is affected by operating temperature. Efficacy is determined by comparing the service life achieved by the battery as a percentage of its service life achieved at 20 °C versus temperature. Ohmic load and operating temperature often jointly determine a battery's discharge rate. Moreover, if the expected operating temperature for a primary battery deviates from the typical 10 °C to 25 °C range, then operating temperature "will often have an influence on the type of battery selected for the application". Energy reclamation from partially depleted lithium sulfur dioxide battery has been shown to improve when "appropriately increasing the battery operating temperature".
   For downhill skiing or winter biking, rechargeable nickel metal or lithium batteries are generally used. If not recharged properly, "battery memory" will shorten the battery's capability to recharge. There are two types of lithium batteries: Li-ion & Li-Polymer, which use several types of heating technologies including copper wire, nichrome wire, metal "mesh" systems, carbon-embedded fabric, carbon fibers and very thin flexible heating technologies that can be printed onto substrate. This has allowed for extra features to be added such as temperature sensors, Bluetooth integration and the ability to control the temperature from a smartphone. 
   When exposed to high temperatures, the lithium-ion batteries in smartphones are easily damaged and can fail faster than expected, in addition to letting the device run out of battery too often. Debris and other contaminants that enter through small cracks in the phone can also infringe on smartphone life expectancy. One of the most common factors that causes smartphones and other electronic devices to die quickly is physical impact and breakage, which can severely damage the internal pieces.
  
  Section::::Examples.
   Section::::Categories and types of batteries.:Cell performance.
  
  A battery's characteristics may vary over load cycle, over charge cycle, and over lifetime due to many factors including internal chemistry, current drain, and temperature. At low temperatures, a battery cannot deliver as much power. As such, in cold climates, some car owners install battery warmers, which are small electric heating pads that keep the car battery warm.
  
  Section::::Capacity and discharge.
   BULLET::::- Dynamic Front Side Bus Throttling (some mobile models), where the speed of the FSB is reduced in half, which by extension reduces the processor's speed in half. Thus the processor goes to a low power consumption mode called Super Low Frequency Mode that helps extend battery life.
   Battery life can be extended by storing the batteries at a low temperature, as in a refrigerator or freezer, which slows the side reactions. Such storage can extend the life of alkaline batteries by about 5%; rechargeable batteries can hold their charge much longer, depending upon type. To reach their maximum voltage, batteries must be returned to room temperature; discharging an alkaline battery at 250 mA at 0 °C is only half as efficient as at 20 °C. Alkaline battery manufacturers such as Duracell do not recommend refrigerating batteries.
  
  Section::::Battery sizes.
   The battery limits the range of temperature at which the device works from between -10 degrees C and 40 degrees C.
  
  Section::::Related Models.
  
  Section::::Related Models.:Victoreen 496.
   The safe temperature range when in use is between −20 °C and 45 °C. During charging, the battery temperature typically stays low, around the same as the ambient temperature (the charging reaction absorbs energy), but as the battery nears full charge the temperature will rise to 45–50 °C. Some battery chargers detect this temperature increase to cut off charging and prevent over-charging.
   Section::::Lifetime.:Self-discharge.
  
  Disposable batteries typically lose 8 to 20 percent of their original charge per year when stored at room temperature (20–30 °C). This is known as the "self-discharge" rate, and is due to non-current-producing "side" chemical reactions that occur within the cell even when no load is applied. The rate of side reactions is reduced for batteries stored at lower temperatures, although some can be damaged by freezing.
   Because the leakage currents in semiconductors increase with temperature, refresh times must be decreased at high temperature. The current generation of DDR2 SDRAM chips has a temperature-compensated refresh structure; refresh cycle time must be halved when chip case temperature exceeds .
   All electrochemical cell batteries deliver a changing voltage as their chemistry changes from "charged" to "discharged". A nominal output voltage and a cutoff voltage are typically specified for a battery by its manufacturer. The output voltage falls to the cutoff voltage when the battery becomes "discharged". The nominal output voltage is always less than the open-circuit voltage produced when the battery is "charged". The temperature of a battery can affect the power it can deliver, where lower temperatures reduce power. Total energy delivered from a single charge cycle is affected by both the battery temperature and the power it delivers. If the temperature lowers or the power demand increases, the total energy delivered at the point of "discharge" is also reduced.
  