Out of juice

摘要

Time was when a household torch used an incandescent bulb and gobbled disposable batteries. Now it is more likely to have a low-power led (light-emitting diode) and a long-lasting rechargeable battery-or none at all: a flick of the wrist or a twist of a handle can provide enough juice for a bright steady light. These trends-lower power consumption, better and cheaper rechargeables, new power sources-are squeezing what used to be a lucrative market. Remote controls for televisions, for example, used to be powered by batteries. Now they can be an app on a mobile phone. The latest gadgets, such as wearable devices, come with batteries built in-typically based on a thin sliver of lithium, not a tube packed with manganese dioxide, alkali and zinc. "There are fewer cavities," says Ali Dibadj of San-ford C. Bernstein, a research firm.