By David Ponce
It’s often the simplest ideas that go the furthest. This simple $5 gadget allows you to convert your AA batteries into a D size. Simply insert the smaller battery inside with the proper polarity, and you’re all set. It would come in handy when looking for some flashlight batteries, for instance, and all you got is the ones in the remote.
Of course, this will do nothing to address the capacity issues, with AA batteries averaging 1,500 mAh, while a D battery usually has about 8,000 mAh. Still, useful little thing for when you’re in a hurry.