Batteries are on our minds a lot due to the wireless keyboard and mouse we have at home. They're great but can go through batteries. This solar battery charger caught our eyes because of its small flexible solar panel. The thin solar panel weighs less than an ounce and it's only 3x3 inches in size. The drawback comes with regard to charge time. It recharges four AA batteries in 5-8 hours - daylight hours only, of course. We're encouraged by all of the new solar devices out there, but we're still waiting for the day when our wireless keyboard and mouse are themselves solar powered.