Remote Controls, Without the AAA Batteries Smartphones, tablets and other portable devices that need electricity rely on batteries that use a chemical reaction. But Maxwell Technologies, a company in San Diego, announced Tuesday that it was providing devices for television remote controls that store electricity without chemicals. The devices, called ultracapacitors, are a little smaller than the two AAA batteries they will replace. They can recharge within minutes and have a life span that will probably outlast the remote control, said Michael W. Sund, a spokesman for the company. Maxwell said it was approached by Celadon, a company that makes remote controls for set-top boxes, with a request for a power system that could work with a remote control. Ultracapacitors are used in many devices, particularly in manufacturing, but they have only pushed out bursts of energy, and basic storage has remained in the chemical battery. The ultracapacitors store energy by putting an electric charge - positive or negative, on plates that are separated by an insulator. Engineers have experimented with the use of capacitors in hybrid and electric cars, where they could provide energy for quick acceleration and recapture the energy generated when a car slows down. Maxwell already sells giant capacitors for use in hybrid transit buses that need to capture energy when they come to a stop. The capacitors in the buses also deliver energy to help get the wheels moving. But using capacitors to provide a steady flow of energy is something new. Still, like other capacitors, the new ones can be recharged quickly. The remote control can recharge in five minutes and run for many hours, maybe even days, depending on how often it is used to change channels, Mr. Sund said. And unlike the lithium-ion batteries used in phones, laptops and, now cars, capacitors do not lose storage space with age. "The speed of charge is an advantage," Mr. Sund said. If you forget to plug it in, it's just a few minutes. The Energy Department's Advanced Research Project Administration - Energy, an energy version of the better-known Defense Advanced Research Projects Agency, is enthusiastic about capacitors, and is financing several projects that use it. Comparing a capacitors" energy storage characteristics to those of a chemical battery is a bit like comparing the water storage capability of a pitcher with that of a roll of paper towels. A paper towel, like a chemical battery, takes a little time to soak up the water and never quite gives it all back - and over time, its ability to store water breaks down. The pitcher can be repeatedly filled quickly and emptied quickly or slowly. So far, no one can build a capacitor that meets the requirements of a smartphone, Mr. Sund said. But his company is working on one that would be an adjunct to a smartphone battery, providing energy for the camera flash, a weak spot in current smartphones. And more capable capacitors are on the way. Maxwell uses a layer of carbon on an aluminum substrate, where the charged particles can be stored. But researchers at the University of California, Los Angeles, are working on a model that uses a single layer of carbon atoms.