ALKALINE DISPOSABLES

They still exist because of convenience, not chemistry: You can buy them—for a pittance—from New York to Nepal. Perfect for occasional-use devices, such as smoke detectors and TV remotes, because of their long shelf life.


NICKEL-CADMIUM (NiCd)

Good for 1,000 discharge cycles. They’re toxic and suffer “memory effect,” when damaging crystals form if the cell isn’t often fully discharged. NiCds are rare except in power tools; their high discharge rates suit big-current draws.

This month's "Why didn't I think of that" award goes to Panasonic's nickel-metal-hydride (NiMH) battery set, which converts AAs to C or D batteries. It comes with rechargeables, but alkalines work as well. Just pop on the appropriate jacket and you're ready. Of course, you get the battery life of a AA, not that of longer-lasting Cs and Ds.


Price: $30; includes six AAs, two AAAs, four adapters, and a charger.

www.panasonic.com

The most promising feature of the Honda Dualnote prototype, shown here, is the least apparent: Under its cool-kitsch skin, which looks like a computer-generated CAD drawing come to life, is a hybrid powertrain. In other words, a big electric motor helps this car's internal combustion engine.