Dear Jim: It might sound silly, but with potential terrorism, snipers, etc., I am concerned about losing the electric power. I cannot afford a back-up generator. What type of battery systems are available? – Peg N.

Dear Peg: Your concerns are not silly at all. People often forget that many home security systems stop functioning when the power goes off and the internal battery runs down. I keep a portable battery backup power supply charged to operate my security system, a TV, light and laptop computer when the power goes off.

There are portable battery power packs available, such as the one I use at home, that allow you to plug standard 110-volt appliances directly into them. Most of these units also have an outlet for 12 volts to start your car in case your car battery runs down or to power other battery-operated devices.

In addition to emergencies, battery power packs are ideal for camping, fishing, picnicking, and using power tools or lights outdoors. They use sealed lead acid batteries so they are safe to move and handle. It is all housed in a plastic case with a handle and built-in electric outlets.

To use batteries to operate household appliances, the direct current battery power must be converted to 110-volt alternating current. This requires the DC power to run through an inverter to convert it to AC. Some power packs have a built-in inverter while others use a plug-in one.

The amount of electric energy stored in a battery is measured in amp-hours. Power packs range in output from about seven to 100 amp-hours depending on the size and number of the batteries inside. The weight also varies from about 10 pounds for a small one to more than 80 pounds for a powerful one.

An 18- to 20-amp-hour model is adequate for most household emergencies and outdoor recreational use. They weigh only about 20 pounds. This size power pack can operate a lamp for 12 hours, a security system for two days, a small television for 10 hours, or a sump pump for two hours.

Most power packs have a tiny charger you plug into a wall outlet. They include either a gauge or LED lights to let you know when they are fully charged. They can also be charged from your car while you drive (plug it into the cigarette lighter) or attach it to solar panels or small windmills for free charging.

Depending on how you plan to use the power pack, there are several features to consider. For strictly home use, just the 110-volt outlets are most important. For use in your car too, consider a model with a built-in air pump and a bright built-in spotlight to see at night and a snap-on red lens to alert others you need assistance.

Write for (instantly download – www.dulley.com) Update Bulletin No. 400 – buyer’s guide of six portable power pack and plug-in inverter manufacturers listing amp-hours, charging time, unique features, weights, sizes, prices, and tips for emergencies. Include $3 and a business-size SASE, and send to James Dulley, 6906 Royalgreen Drive, Cincinnati, OH, 45244.