Dear Straight Dope:
My wife insists on putting batteries in the refrigerator, to "make them last longer." But if that really did extend the life of the battery, wouldn't batteries be sold in the refrigerated section of the supermarket? A side question: if my wife is right, should you let them return to room temperature before using them?
Bob in West Point, PA
SDStaff Ken replies:
You’re both right, to an extent.
How does a battery (technically a cell — a battery is several cells connected in series) work? A chemical reaction generates an electrical charge inside the battery shell, and the charge is then used to power devices.
Since it’s a chemical reaction that generates the electricity, temperature can slow down or speed up the reaction. The colder they’re kept, the slower the “manufacture” of the charge happens. Since batteries have a limited amount of chemical in them, it seems reasonable to think that refrigeration will slow down the reaction until we’re ready to use it. You probably noticed that batteries get hot when they’re used — same principle. You might be too young to remember when it was necessary to add water to car batteries. The reaction would boil it off — that pesky heat again.
This is the conventional wisdom, but wait: we haven’t heard from the professionals. This next is from Ray-O-Vac, Michael Jordan’s boss nowadays:
Batteries depend on internal chemical reactions to produce power. Chemical reactions are accelerated by high temperatures and retarded by low temperatures. Therefore, to minimize power loss during storage, batteries should ideally be stored at a maximum temperature of 77 F (25 C). Refrigerated storage is neither necessary nor recommended.
What gives? Does Ray-O-Vac not want us to refrigerate batteries because they figure warm batteries will run out sooner and we’ll buy more? Not necessarily. A common misconception is that batteries are generating electricity even when they’re not being used. That’s not the case. Until somebody throws the switch, a battery only has electrical potential. If no juice is flowing, no chemicals are reacting, and there’s no point in refrigerating the battery. Quite the contrary — since refrigeration slows a reaction, the electricity won’t be there when you want it. That’s why car batteries don’t work well in subzero temperatures.
Now, it’s true all batteries lose some charge over time in storage. (Some lose a lot — rechargeable nickel-cadmium batteries, for example, are notorious for discharging when not in use.) Refrigeration presumably will retard this process. But the thinking seems to be that the slow loss of charge is a small price to pay for the advantage of having the electricity available when you want it, rather than having to wait for the battery to warm up. So unless your wife was planning to store those batteries for a loooong time, she’s probably best off just keeping them in a drawer.
SDStaff Ken, Straight Dope Science Advisory Board
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