One of the things we take for granted in our high-tech world is batteries. As we have become more and more “wireless,” our dependence on batteries has increased. So much of our personal and office equipment runs on battery power, whether it's your PDA, cell phone, pager, clock, or wireless microphone.

It's important to understand some basics. There are two major divisions among batteries — primary and secondary. Primary batteries are used once and thrown away. These include alkaline, lithium, zinc air, and silver oxide. Secondary (rechargeable) are made of nickel-metal hydride, nickel cadmium, lithium ion, and sealed lead acid. Here is a summary:

Alkaline — This most popular type of battery is used in a wide variety of devices (radios, flashlights, PDAs, toys, tape recorders). It has a shelf life of five to seven years, and has a “sloping discharge” (it discharges gradually and becomes weaker). Alkaline batteries are popular for high-drain applications.

Ni-Cad (or nickel-cadmium) — These are more powerful than alkaline batteries, and used to be popular — although they are becoming less so — for cordless phones and other moderate-power devices. The rechargeable ones have a “memory effect,” and unless they are discharged completely, they will operate for shorter and shorter times.

Lithium — These last the longest in high-tech devices (such as digital cameras.) They work well in lower temperatures, and have a shelf life of up to 10 years. They are the best non-rechargeable power source for heavy-drain and frequent usage. They have a “flat discharge” (that is, they maintain the same level of power until they die). Lithium-ion (rechargeable) batteries are the preferred choice for laptops.

Nickel-metal hydride — These are the most cost-effective for frequent usage and heavy-drain devices (i.e., digital cameras). They can be recharged up to 1,000 times. They do have a limited shelf life, and can lose one percent of their power per day.

Ken Pickle, CPCU, CMP, is manager, incentives and conferences, for Safeco Insurance Cos., Seattle.

Battery Use and Care Tips

  • When replacing batteries, gently rub the contact surfaces of the battery and the battery compartment with a clean rough cloth or a clean pencil eraser.

  • If a piece of equipment will not be used for several months, remove the batteries.

  • Always replace all the batteries in a compartment at the same time.

  • Use the batteries recommended by the manufacturer. And don't mix types.

  • Store batteries in a cool, dry place at normal room temperatures.

  • Do not carry loose batteries in your pockets. You can be attacked by “hot pocket.” (Keys or other metal objects can make connection with the terminals, and heat up.)

  • Use a good quality battery charger — one that will turn itself off when the battery is fully charged. (Overcharging is the most common cause of early battery failure.)

  • Don't leave the battery charger plugged in when not charging. It will continue to use power.

  • When using rechargeable batteries, keep the batteries together as a set. Use and recharge them together.