Buying and Maintaining Rechargeable Batteries
Rechargeable batteries offer power on-the-go with two key advantages over their disposable equivalents: they’re far cheaper in the long run, and they’re better for the environment.
But because there are so many different types and brands — and because the upfront cost of purchasing rechargeables is higher than with buying disposables — picking out rechargeable batteries is a little more difficult than battery shopping used to be. Even storing and caring for these batteries takes a little more effort.
How Many, How Much?
Before making any rechargeable battery purchase, it’s important to consider your own needs. How many battery-operated devices do you own, and what sizes of batteries do they use? Take inventory and make a list to determine what quantities and sizes meet your needs.
Rechargeable batteries can vary in their electrical capacity, even within a single size, type and brand. The milliamp per hour rating, designated as “mAh”, tells you how much juice a battery can hold. The higher the mAh, the more power it packs. So when you’re evaluating your needs, make a note of any devices where extra-long battery life is important, and consider splurging on batteries for that device that have a high mAh rating.
The materials used to make rechargeable batteries have changed quite a bit even in the short time since rechargeables hit the consumer market. When the technology was new, most were nickel cadmium (NiCd), though these are now fairly uncommon for a couple of reasons.
One reason is because cadmium is a hazardous material, so NiCd batteries can pose risks when they’re ruptured or when they collect in landfills. But another reason is because of the “memory effect” — when NiCd batteries are recharged before they’re fully drained, they can incorrectly “remember” how much power they can hold. After a few cycles of being recharged at 50 percent, a NiCd may only think it has half the capacity it actually has.
Today, most of the rechargeable AA and AAA batteries you see in the store are nickel metal hydride (NiMH). These have no memory effect and are much lighter than NiCd batteries. But they don’t outperform in every area — they also tend to drain faster, have shorter lifespans and struggle to perform in cold conditions.
The newest battery type on the scene are lithium ion batteries (Li-ion). These are the sealed batteries you have in your phone and computer, but they’re gradually emerging as an option for everyday AAs and AAAs. Li-ions combine the best features of NiCd and NiMH batteries, and are poised to be the go-to choice — at least until the next battery breakthrough comes along.
Getting the most bang for your battery buck also requires you to charge and store your batteries with care. For NiCd batteries, as explained above, it’s crucial that these batteries be fully drained before recharging. If necessary, use a charger with a “discharge cycle” feature, which can drain batteries before starting the charge cycle. NiCd batteries should also be fully drained before long-term storage.
The opposite is true for NiMH batteries — these should be kept fully charged as often as possible, including preparation for storage. This is likewise a good practice for Li-ion batteries. Keep these charged so they’re ready when you need them.
Rechargeable batteries don’t last forever, so it’s also important to keep sets of batteries together. Don’t mix up rechargeables of different ages and brands, which will make it more difficult to tell when it’s time for replacement.
Your licensed, local electricians are happy to help you get the most out of your batteries — even if their #1 job is keeping the power on at home.