Regardless of how they are stored, all batteries gradually lose their charge over time. However, some storage methods will conserve more charge than others will. One of the most important factors affecting the amount of charge a battery will lose during storage is the temperature.
Ideal Storage Temperatures
Most manufacturers recommend storing batteries at room temperature. However, you may have also heard that you can extend the life of a battery by keeping it in the freezer or refrigerator. In general, the ideal storage environment is dependent on the type of battery you plan to store.
Lithium-Ion, Nickel-Based and Lead-Based Batteries
According to Battery University, lithium-ion, nickel-based and lead-based batteries will retain more of their charge if they are stored at low temperatures. The greatest retention is obtained at 0 degrees Celsius, or approximately 32 degrees Fahrenheit. As storage temperature increases, the amount of charge lost over time increases as well. Thus, to obtain the maximum charge retention, these batteries should be stored at cooler temperatures when possible. However, Battery University cautions against storing these types of batteries at any temperature lower than 0 degrees Celsius.
According to Duracell, alkaline batteries should be stored at room temperature. Duracell also notes that cooler temperatures may result in a higher level of charge retention. However, the difference is so small that refrigeration is not typically necessary.
The Dangers of Extreme Temperatures
While storing batteries in cooler temperatures is recommended, exposing them to extreme temperatures is not. In most cases, batteries that have been exposed to extremely high temperatures will sustain more damage than those that have been exposed to extremely low temperatures.
For example, according to Apple, the lithium-ion batteries in its products may exhibit diminished capacity when used in extremely cold temperatures, but their capacity should return to normal after the battery returns to room temperature. On the other hand, when Apple's batteries are exposed to high temperatures, the damage is often irreversible, and storage capacity is reduced permanently.
Likewise, you should also avoid storing alkaline batteries at high temperatures. Duracell reports that high temperatures speed the degradation of the chemicals contained within an alkaline battery, thus causing the battery to lose charge rapidly.
Other Storage Recommendations
In addition to storing your batteries at the proper temperature, you should also keep your batteries dry. In general, Duracell recommends storing batteries in an environment with less than 65 percent humidity. Batteries should be removed from equipment for storage, and any batteries that leak or rupture should be discarded immediately.