the test of the battery

No one wants a camera to conk out at a holiday gathering or a brand-new gizmo to run out of juice before the new year. To keep those disappointments at bay, see our Ratings (available to subscribers) of 17 AA batteries, the size most often used in radios, flashlights, remote controls, digital cameras, and many toys. We tested four types of AAs, including rechargeables that work right out of the package without an initial charge.

How we tested

We put the batteries in identical cameras and used our usual protocol: Turn camera on, zoom in, zoom out, zoom in, turn on flash, take five pictures with 30 seconds between each, turn off camera, wait 10 minutes, repeat. For each battery, we kept going until the cameras could not take pictures. We tested "precharged" rechargeables two ways: right out of the package, to see how many shots precharging provides; then as a regular rechargeable, using two charge/discharge cycles to obtain the number of shots used in the Ratings, which are available to subscribers. (Some manufacturers claim that up to a thousand recharges are possible, but we didn't have years to test.)

What we found

There are big differences in how long batteries last. A score of excellent means that a battery provided more than 511 pictures; very good, 256 to 510; good, 128 to 255; fair, 50 to 127.

Lithium batteries did best, but two rechargeables came close. And note that the rechargeables in the Ratings (available to subscribers) are 2,000 milliamp hours (maH). When we tried higher-capacity (2,450 maH) rechargeables, they produced more shots, as expected. Precharged batteries were good right out of the package, providing 246 shots on average without being charged.

There are also big differences in price per pair and per 50 shots (see Ratings, which are available to subscribers). Alkalines tend to be least expensive; rechargeables are priciest, but cost per 50 shots falls the more they're recharged. You'll pay about $15 to $20 for a charger.

Bottom line

For digital cameras, often-used toys, and other devices drawing bursts of power, make the greener choice: rechargeables. The Sanyo Eneloop and Sony Cycle Energy are very good and took more than 350 shots on a full charge. Another option is a single-use lithium battery. The Energizer Ultimate took 678 pictures; the Energizer Advanced, 562.

For flashlights, remote controls, and other devices drawing little power, consider single-use alkaline batteries, which should have a shelf life of several years. The Panasonic Evolta took 237 shots, more than any other alkaline. Almost as good and far less expensive is the Kirkland Signature, sold at Costco and only in a 48-pack. Don't buy the implied claim of the CVS Long Lasting alkaline. It produced the fewest shots of all: 92.

Did you know?

You should store batteries separate from one another and from other metal objects in a cool, dry place (no need to store in the refrigerator). Don't mix battery types, sizes, or ages. Rechargeable batteries should be recycled to keep their heavy metals out of landfills. To find out where to recycle, go to www.rbrc.org, the Web site of the nonprofit Rechargeable Battery Recycling Corp.