Best batteries: performance varies greatly by type.(Buyers guide)

Think that one kind of battery is fine for all your gear? Think again. The best cell for your digital camera isn't the best value for your CD player, our new tests show. Pick the wrong battery for your camera and it could die in 37 minutes.

Moreover, claims involving newer technologies can be deceiving. Duracell and Panasonic nickel oxy-hydroxide batteries meet their limited claims for picture-taking ability, we found in our tests. But there are far better and cheaper choices for your camera and other devices.

What are the real deals? This report, including our new tests of disposable batteries--which by far have the largest share of the market--offers the guidance you need.

THINK HIGH VS. LOW USE

For gear with a high power drain or for devices you use often, rechargeable batteries are much more economical than disposables. That's even after you factor in the cost of a $30 to $50 recharger, because the batteries can be recharged hundreds of times. Our past tests have shown that rechargeable nickel metal hydride (NiMH) batteries perform better than rechargeable alkalines for cameras and other such gear.

But NiMH cells discharge when they're not in use, so they're not the best choice for battery-powered devices that often sit idle, such as a flashlight or a remote control. Even for those items in which you plan to use rechargeables, it can be a good idea to keep disposables on hand as a backup.

HOW TO CHOOSE DISPOSABLES

Our latest tests of 16 disposable AA batteries--lithium, nickel oxy-hydroxide, and alkaline--show that there's a huge difference in performance …