Energy Advice

Welcome to our energy advice column. Here we summarize publicly available information on the many ways you can save money on your energy bills as well as general topics on renewable energy. We try to keep our advice short and to the point.

BATTERIES: DISPOSABLE VERSUS RECHARGEABLE

If you're dealing with solar products, you will most likely run into batteries, large and small. With a bit of knowledge about the different types of batteries, you can select the right batteries and save money, too.

We will first cover the small disposable batteries—the ones we purchase for most portable devices like radios, cameras, many toys, and flashlights.

Most disposable batteries are of the alkaline type. They come as AAA, AA, A, C, D, indicating shape, size, and voltage. For example, an AAA battery is very small and provides 1.5 volts. A D battery is much larger, its shape is rectangular, and it provides 9 volts of charge.

Obviously, the appliance determines the type and the number of batteries needed. But how do you rate these batteries? It's not easy. What determines how long a battery will last is, first, its capacity rating (usually described in milliamps or mA and, second, what the appliance consumes per hour. A typical AA battery may be rated anywhere from 500mA to 2600mA or higher. The larger the number, the longer the charge. Some manufacturers don't provide this information easily. One major manufacturer, for example, places it in the back of the package as a code.

The pack of C type batteries pictured on the right has a number on the top right corner: there’s a C followed by the code MN1400R4 1.5 V. The 1400 represents the battery's capacity. Once you locate this number, you can calculate the cost per mA and determine its value for the money.

For example, if a pack of four 1000mA batteries costs $6.00 and a pack of four 1800mA batteries of the same type costs $7.99, which pack provides more value? Divide the price of the package by the number of batteries it contains: $6.00/4=$1.50 and 7.99/4=$1.99. Then divide the cost of each battery by its capacity: $1.50/1000=$.0015 and $1.99/1800=$.0011. By performing these simple calculations, we can see that the higher-priced pack actually provides more value than the lower-priced one. Also, its charge of 1800mA will last longer than the smaller 1000mA battery.

As already stated, some manufacturers don't want you to know how much capacity is in their batteries. Let's take a look at a few popular brands and see what we can find out:

The Maxell website lists its batteries, but says nothing about their charge capacity. Radio Shack's Enercell site has a lot of good information on batteries, but they, too, stay away from providing battery capacity on their Alkaline types (they know that most of us buy disposable batteries in bulk without thinking much about battery capacity). The Energizer site does provide full information on their various batteries. In fact, their AA Alkaline Energizer is listed at 2850mA.

So based on our calculations, which batteries provide the best value for the money? In the above example, the Maxell batteries appear to have the best price. Next would be the Radio Shack pack of 40. The Energizer, however, tells you that their batteries pack 2850mA of charge. This is a lot of charge for such a small battery. I would put my money on the Energizer. At least, I know how much charge capacity I am buying.  Having this piece of information will also help me figure out exactly how long I can expect to run my appliance before the battery goes dead. Every appliance's manual (or sometimes, the label in the back) states how much it consumes in milliamps. You simply take this number and divide it into the battery's number to get the total number of hours that the appliance will run before having to change batteries.

A generic brand with a low expiration date for less money is rarely a bargain.