The storage instructions on a typical package of household alkaline batteries usually advise consumers to store them in a cool, dry space. This advice is generally meant to discourage the storage of batteries in hot, humid places such as kitchen drawers or glove compartments. One popular rumor about the storage of batteries suggests keeping them in a refrigerator or even a freezer to extend their shelf life. Modern science has weighed in on this rumor, and the final answer depends on what type of batteries are involved and the definition of "extended shelf life". For the most part, many experts say, the practice of storing batteries in a refrigerator creates more problems than it solves.
Household alkaline batteries generate their electrical power through a chemical reaction. Each battery contains alternating layers of two different metals and an alkaline liquid which acts as an electrolyte. When an electrical circuit is complete, free electrons flow out of the positive poles of the batteries, move through the device, and return to the batteries through the negative poles. This process continues until the electrolyte fluid can no longer keep the free electrons flowing. As long as unused batteries are kept in a cool, dry space, they could remain usable for five years or more. The electrolyte fluid retains an estimated 90% of its power as long as the batteries are not allowed to overheat or become unsealed.
This is where the refrigeration issue enters the picture. A household refrigerator typically holds food at 40 degrees Fahrenheit (approximately 10 degrees Celsius) or lower, and the atmosphere inside a refrigerator is very low in humidity. In other words, a refrigerator appears to be the ideal environment for the storage of alkaline batteries. All batteries will eventually lose their charge due to a slow drain of their electrolytes' power. The lower the ambient temperature, however, the slower this power drain could be. According to the results of several scientific tests, batteries stored at refrigerator temperatures do indeed last longer than batteries stored at higher temperatures, but on average the difference is only a few percentage points. Alkaline batteries stored in a refrigerator may retain 93% of their power after five years, compared to 90% for non-refrigerated batteries stored in cool, dry areas.
This isn’t to say that refrigerating or even freezing alkaline batteries would be a complete waste of time, but it isn’t strictly necessary. Chilled batteries would require additional time to warm up to proper operating temperature, which means they could not be taken straight from a refrigerator and placed directly into a flashlight or radio during an emergency. The cold batteries may also start to condense as they thaw, which means moisture could enter the appliance and cause a number of problems.
In short, storing batteries in a refrigerator might add a few more minutes to their shelf life, not enough to justify the additional time they’ll need to return to usefulness. It is far more important that you store your unused batteries away from heat sources and areas prone to high humidity. Heat and humidity will cause stored batteries to leak fluid, and prolonged storage in a device may also encourage corrosion and leakage.
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This is where the refrigeration issue enters the picture. A household refrigerator typically holds food at 40 degrees Fahrenheit (approximately 10 degrees Celsius) or lower, and the atmosphere inside a refrigerator is very low in humidity. In other words, a refrigerator appears to be the ideal environment for the storage of alkaline batteries. All batteries will eventually lose their charge due to a slow drain of their electrolytes' power. The lower the ambient temperature, however, the slower this power drain could be. According to the results of several scientific tests, batteries stored at refrigerator temperatures do indeed last longer than batteries stored at higher temperatures, but on average the difference is only a few percentage points. Alkaline batteries stored in a refrigerator may retain 93% of their power after five years, compared to 90% for non-refrigerated batteries stored in cool, dry areas.
This isn’t to say that refrigerating or even freezing alkaline batteries would be a complete waste of time, but it isn’t strictly necessary. Chilled batteries would require additional time to warm up to proper operating temperature, which means they could not be taken straight from a refrigerator and placed directly into a flashlight or radio during an emergency. The cold batteries may also start to condense as they thaw, which means moisture could enter the appliance and cause a number of problems.
In short, storing batteries in a refrigerator might add a few more minutes to their shelf life, not enough to justify the additional time they’ll need to return to usefulness. It is far more important that you store your unused batteries away from heat sources and areas prone to high humidity. Heat and humidity will cause stored batteries to leak fluid, and prolonged storage in a device may also encourage corrosion and leakage.
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An interesting tidbit: it technically costs more to refrigerate alkaline batteries, as you're paying for the slight electricity bump used by your refrigerator, and you save very little power. As far as the other types go, most are rechargable, so there's no real need to refrigerate them to hold their charge, just putthem in a charger before you use them. Also, they last a bit longer than a few days at room temperature.
NiMH and NiCd batteries self discharge at a much faster rate than alkaline batteries. In fact, at "room temperature" (about 70 degrees F) NiMH and NiCD batteries will self discharge a few percent per day. Storing them at lower temperatures will slow their self discharge rate dramatically. NiMH batteries stored at freezing will retain over 90 percent of their charge for a full month. So it might make sense to store them in a freezer. If you do, it's best to bring them back to room temperature before using them.
Even if you don't freeze your NiMH batteries after charging them, you should store them in a cool place to minimize their self discharge.
NiMH and NiCd batteries self discharge at a much faster rate than alkaline batteries. In fact, at "room temperature" (about 70 degrees F) NiMH and NiCD batteries will self discharge a few percent per day. Storing them at lower temperatures will slow their self discharge rate dramatically. NiMH batteries stored at freezing will retain over 90 percent of their charge for a full month. So it might make sense to store them in a freezer. If you do, it's best to bring them back to room temperature before using them.
Even if you don't freeze your NiMH batteries after charging them, you should store them in a cool place to minimize their self discharge.
