When power fails, replace all old batteries rather than mixing old and new together.

Most of the mobile devices we rely on to make our lives simpler and more enjoyable run on batteries, and it can be annoying and expensive if those batteries run out too quickly. Whether you use rechargeable or disposable batteries, there are some simple tips you can follow to make sure you're getting the most battery bang for your buck.

Jim Tessmar is the owner of The Battery Hut in Burbank, Calif. Here he offers hints on making the most of the batteries in different kinds of devices:

• Don't mix batteries. Let's say you own a flashlight that uses more than one battery, and you find the bulb starting to dim. It may seem like a money-saving move to take out just one of the dying batteries and replace it with a fresh one, but Tessmar claims that this is a mistake. The new battery will quickly drain itself to the level of the old one, and you will have wasted money. It's a much better move to replace all weak batteries with new ones.

• Watches. According to Tessmar, a typical watch battery in constant use lasts for about a year or a year and a half. But if you own several watches, particularly ones that you wear only on special occasions, there is no reason that they have to be running all the time. Tessmar makes it a point to pull the pin out of watches he is not wearing, thus conserving the battery power and greatly extending the battery life.

• Cordless phones. The battery inside a typical cordless phone is designed to last for 500 to 1000 charges. But if you always keep the handset close to the base unit instead of on it, and remember to replace it on the base every night, you can get three to four years out of the battery. By spreading out the time between recharges, you will be extending the battery's lifespan, and that will save you money on replacements.

How Batteries Work
www.howstuffworks.com/battery.htm

Batteries.com
www.batteries.com

New Technology Batteries Guide: Battery Handling and Maintenance
www.nlectc.org/txtfiles/batteryguide/ba-hand.htm

Duracell
www.duracell.com

Energizer
www.energizer.com