Portable electronics have become an integral part of our lives, and the batteries that keep them operating are now a major issue in energy use, the economy and the environment. Apart from devices like mobile phones, laptop computers, ebook readers and notebooks, which use built-in rechargeable batteries, there are electronic devices like iPods and electronic cameras that use replaceable batteries. And how they use them! A camera that gets even moderate use can go through several batteries a month. The number of batteries being used is very large and, as with all large numbers, even small changes can make a significant difference – including in savings for you!


In 2012, approximately 1.4 billion replaceable batteries were sold and used in the UK, at a cost of approximately £520 million. Of that, about 90% went straight into landfills after use. The majority of these are alkaline batteries which are designed for a single use and are not rechargeable, but they have the advantage of a long shelf-life. Rechargeable nickel metal hydride (NiMH) batteries cost more, initially, including the cost of the recharging unit but (obviously) they can be used again and again. Sounds like an easy choice, doesn’t it? There are some issues to consider first, however.


Shelf Life

Alkaline batteries have a long shelf life, which means that the battery only loses less than 1% of its charge per month. This means that, after sitting in your desk drawer for five or even ten years, an alkaline battery will still have enough charge left in it to be useful. A rechargeable NiMH battery, on the other hand, will lose several percent of its charge per day. So, if you are using that camera or iPod frequently and have spare batteries ready to hand, rechargeables are a good choice. If you leave your camera on the shelf for months at a time, but want it ready to use in case you want to snap a picture for a special occasion or the odd meteorite passing overhead, then an alkaline is for you.



Heat is the enemy of battery charges. At room temperature (say, 21° C) both types of batteries will lose their charges as described above. Under warmer conditions, such as 30° C near a radiator, both types of batteries can lose their charges at a rate 25 times faster. On the other hand, keeping an alkaline batteries in a freezer doesn’t really extend their shelf life all that much, but an NiMH battery can still have 90% of its charge after a month in a freezer set to -4° C. If you have a handful of NiMH batteries charged up, it’s worthwhile to keep them in the freezer. Just be sure to let them warm up to room temperature before you put them in your device.


Length of Recharge

There are two types of rechargers: The old-fashioned plug-and-forget kind and the more expensive “smart” chargers that charge more quickly and then shut themselves off. Guess what? In this case, quicker really is better. Slow charging reduces the lifespan of NiMH batteries and over-charging will seriously damage them. If you’re going to invest in rechargeable NiMH batteries, you might as well get as much use out of them as you can.



Eventually, even rechargeable batteries no longer efficiently hold their charge. When it’s time to get rid of them, for pity’s sake recycle them, don’t just throw them away. Not only can the raw materials in them be recovered, but that way they aren’t in a position to leach toxic heavy metals into the soil in a landfill.


The cost of replaceable batteries for electronics can add up so much that it doesn’t take long before the cost of the power exceeds the price of the device itself. With smart battery choices, you can enjoy your music and your pictures at a much lower cost.