Some people swear by storing their batteries in the refrigerator to extend the lifespan of the battery and keep them fresh (apologies for the obvious food-storage joke). But does it actually help? Is there any legitimate reason for putting your batteries in cold storage?
Dear How-To Geek,
I was looking for a little battery storage box on Amazon today with the goal of keeping my discharged rechargeable batteries in one box and the freshly charged batteries in another. While looking at the battery storage boxes I noticed a bunch of them (like this Dial AA Battery Storage Box) were labeled “Suitable for refrigerator storage”. What the heck? Why would you put your batteries in the refrigerator? I search online for a definitive answer, but it seems like every other web site contradicts the one before it. What’s the deal? Should I be putting my batteries in the refrigerator or not?
You certainly have the right to be puzzled by the topic and then confused by the search results you found; there is a ton of misinformation mixed in with outdated information floating around. The five second summary on the subject is that some batteries, in some situations, actually do benefit from refrigeration. But practically speaking, most of the time nobody should be putting their batteries in the fridge. Let’s dig into the subject a little to see when it would be appropriate.
First, let’s look at why people are even putting their batteries in the refrigerator. The underlying principle (which is actually scientifically sound) is that the colder temperature slows the rate of energy discharge. Every battery has a rate of self-discharge, the rate at which it loses a percent of its stored energy while just sitting there doing nothing (e.g. in the package, tossed in the junk drawer, etc.)
This self-discharge occurs because of what are known as “side reactions”, chemical reactions that occur within the battery even when there is no load applied to it. There is no way to avoid self-discharge, but improvements in battery design and manufacturing have significantly reduced how much energy is lost during storage. Here’s how much common battery types typically discharge per month at room temperature (around 65F-80F).
- Alkaline Batteries: These are your most common disposable batteries: the kind you buy, use until they’re discharged, and then dispose of them. They’re quite shelf-stable and typically lose 1% or less of their charge per month.
- Lithium-ion Batteries: Found in laptops, high-end portable power tools, and mobile electronics, lithium-ion batteries have a discharge rate of around 5% per month.
- Nickel-Cadmium (NiCa) Batteries: Although not widely used today, nickel-cadmium batteries were the first widely adopted rechargeable battery. You can still find them on some portable power tools and in other applications, but few consumers are buying them today for light home rechargeable use. The discharge rate on nickel-cadmium batteries is typically around 10% per month.
- Nickel Metal Hydride (NiHM) Batteries: Nickel metal hydride batteries largely replaced NiCa batteries for consumer use (especially in the small battery market). Early NiHM batteries had a rather high rate of discharge and could lose up to 30% of their charge per month. Low self-discharge (LSD) NiHM batteries were introduced in 2005 and have a discharge rate around 1.25% per month, which is on par with the low discharge rate of disposable alkaline batteries.
Looking at the discharge rates, it makes sense that in some applications some people would want to put batteries in the fridge. If you were a photographer that needed to store a bunch of early generation NiHM batteries for your flashes, for example, it might have made sense to charge them all at once, put them in the fridge, and then throw them in your gear bag the morning of a big event.
Practically speaking, however, there’s next to no reason to put your batteries in the fridge. Whatever gains you might get in shelf-life using the technique would be offset by potential problems. Micro condensation on and inside the battery can damage it and cause corrosion. Extremely low temperatures (such as a very chilly portion of the fridge or placing them in a freezer as some people erroneously advise) can further damage the batteries. Even if you don’t outright damage the battery, you have to wait for the battery to warm up to use it and keep it from gathering condensation if the room is humid.
In essence, you’re risking ruining your batteries to squeeze a few months of storage out of them and, further, the batteries that benefit most from cold storage are rechargeable and could have just been recharged prior to your intended use. To seal our stance on leaving your batteries at room temperature, the manufacturers themselves officially recommend against it. So, buy your battery storage box, but keep it in a cool, dry, and non-refrigerated location.
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