Storage batteries, also known as rechargeable batteries or secondary cells, are objects that store energy until needed to power an electronic device. They generally have similar sizes and voltages as one-time-use batteries, which are also called primary cells. Unlike primary cells, storage batteries can be drained and then recharged, allowing for repeated use. This provides numerous benefits to users, particularly in terms of financial and environmental effects. They do have some disadvantages when compared to primary cells, however, which is why storage batteries have not totally supplanted one-time-use batteries.
All batteries produce electricity through the interaction of chemicals contained within the battery’s body. Primary cells include chemicals such as zinc, carbon, or silver that produce electricity when combined in the correct proportions. This process causes the chemicals to deteriorate; when they have deteriorated the point they no longer create electricity, the battery is useless and must be discarded or recycled. The battery could not be reused without replacing the chemicals, which would be a prohibitively expensive process.
Storage batteries use different chemicals, such as nickel, lithium and cadmium, to produce identical amounts of electricity as compared to primary-cell batteries. These chemicals do not deteriorate as quickly, so storage batteries can be recharged and reused dozens or hundreds of times. Unlike primary cells, they lose their charges over time, even when not in use, making them impractical for devices such as emergency flashlights or smoke detectors. They are also more expensive than primary cells, especially when combined with the cost of a charging device.
The chemicals in batteries, whether primary or secondary, are generally toxic; this is why used batteries should only be taken to a facility that is approved for disposing of such chemicals. For this reason, storage batteries are more environmentally friendly than primary-cell batteries. For devices such as cameras, power tools and laptop computers that are in constant use, the higher initial cost of storage batteries and chargers is a fraction of the comparable cost of using disposable batteries over the lifetime of the device.
Most automotive batteries are lead-acid storage batteries; they contain a charge for starting the car’s electrical system, and can be recharged by connection to a powering device or another auto battery. Solar-power systems also use storage batteries that can be recharged by connection with solar panels. These solar systems can charge small devices such as laptops or cell phones, or be converted to household current for daily use.