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Battery Shelf Life

By Bobby George

As batteries get less and less expensive and smaller and easier to store, many people choose to buy batteries in bulk and store what they don't immediately use. This is a smart idea and one that can eliminate a lot of frustration and an extra trip to the store when a battery dies in a device you depend on. But what happens if you go to get a fresh set of batteries from your stash and realize they aren't so fresh after all? If the batteries are left in storage too long, or are stored in unfavorable conditions, they may fail to perform properly when you need them to.

The ability of a battery to remain unused and in storage while still maintaining a level of functionality is referred to as the battery's "shelf life". The shelf life can vary widely across battery types and storage conditions. When storing batteries, it is always important to remember that the cooler the environment, the better. While you don't want to freeze a battery, warm conditions decrease the shelf life considerably. Think of leaving some batteries in your glove compartment, for example. They won't last long at all. Cool, dry, dark conditions like a air-tight container in a storage closet or garage are ideal.

While lots of battery manufacturers will boast shelf lives of 7-15 years, the practicality of storing batteries that long is low. These estimations also account for the entire capacity of the battery. So, while the batter may indeed keep power for that long period of time, it may lose 50% capacity in the first 3 years and only retain 5% capacity towards the end of the estimated shelf life. Chances are, if you tried to use the battery after about 5 years, it would perform very poorly.

Battery type plays a central role in determining shelf life. Rechargeable NiCD and NiMH batteries have the shortest shelf life, meaning it is a good idea to buy what you need, maybe a spare or two, and only buy more when you need them. Alkaline batteries have an excellent shelf life compared to most rechargeables and can usually be bought in bulk and used when needed. However, it is always a good idea to test a few of your alkaline batteries in storage periodically to measure their capacity loss. Some battery manufacturers used to include battery testers either in the battery packaging or on the batteries themselves. This technology is no longer used extensively, but battery testers can be purchased for a reasonable price. Also, you may want to buy fresh batteries to go in important devices such as smoke detectors and hearing aids. Lithium batteries have an excellent shelf life as well, and can be stored for long periods without losing much charge capacity. For this reason, it is sometimes wise to buy an extra battery for a laptop, camcorder, digital camera, or cell phone that takes a lithium battery to keep as an emergency backup. It will store very well and can be used as a main battery if the original ever dies, gets lost, etc.

If you are interested in buying batteries in bulk, please visit this page. Or, if you would like to pick up a spare battery as a backup, choose a category on the left.