They're putting several brands of AA batteries to the test.
Natasha McDermott gets tired of putting new batteries in her kids' toys.
"They're expensive! I have to run out and buy batteries, and it's a complete hassle," she said.
AA batteries are the most widely sold. Consumer Reports tested a dozen, including ones from Rayovac, Energizer, and Duracell, as well as some store brands.
"We looked at different types of batteries - lithium, nickel oxyhydroxide, and alkaline," said Sarah Goralski with Consumer Reports.
To measure how long batteries last, testers load them into identical digital cameras. They zoom three times, take five photos with the flash, zoom three more times, then take five photos without the flash.
After a 10-minute rest, the test is repeated again and again until the batteries die.
Walgreens Alkaline Supercell -- the lowest-rated battery -- took only 133 photos. Compare that to the Energizer Advanced Lithium -- the top-rated battery -- which took 809 photos. But a four-pack costs almost $11.
"Lithium batteries cost more, but they last longer, so you save in the long run," Goralski said.
But you have to be careful which lithium batteries you buy. While that top-rated Energizer Advanced Lithium took 809 photos, the Energizer Ultimate Lithium took just 470.
Lithiums are best for digital cameras, which use a lot of energy.
For remote controls and devices that use less power, go with alkalines. The Duracell Ultra Advanced are the top-rated alkalines and cost around $7 for a four-pack.
And for toys, opt for rechargeable batteries. They'll save you the most.
Consumer Reports says most alkaline batteries can be thrown out in the trash, but rechargeables should be recycled. They contain toxins that should not go into the landfill.