One of the things we take for granted in our high-tech world is batteries. As we become more and more “wireless,” our dependence upon batteries increases, because so much of our personal and office equipment runs on battery power: PDAs, cell phones, pagers, clocks, wireless microphones, etc. Batteries give us convenience in our jobs and lives, but batteries can be expensive, so it's important to understand a few basics.

There are two major types of batteries: primary and secondary. Primary batteries are used once and thrown away. These include alkaline, lithium, zinc air, and silver oxide. Secondary (rechargeable) batteries are made of nickel-metal hydride, nickel cadmium, lithium ion, and sealed lead acid. Here is a summary:


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

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-drain devices. The rechargeable ones have a “memory effect,” and unless they are discharged completely, will operate for shorter and shorter times.


This type of battery lasts the longest in high-drain devices. Lithium batteries work well at lower temperatures and have a shelf life of up to 10 years. They are the best nonrechargeable power source for high-drain and frequent-usage devices. They have a “flat discharge,” which means that they maintain the same level of power until they abruptly cease functioning. Lithium-ion (rechargeable) batteries are preferred for laptops.

Nickel-metal hydride

These are the most cost-effective batteries for frequently used, high-drain devices. Nickel-metal hydride batteries can be recharged up to 1,000 times. On the down side, they have a limited shelf life and can lose 1 percent of their power per day.

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

Battery Care and Feeding

  • When replacing batteries, use a clean, rough cloth or a clean pencil eraser and gently rub the contact surfaces of the battery and the battery compartment. This will remove any buildup or debris.

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

  • Always replace all the batteries in a device 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 high-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 you're not charging batteries. The unit will continue to use power.

  • When using rechargeable batteries, keep them together as a set. Have more than one set, and use and recharge each set as a unit.