page_title: Rechargeable battery
section_title: Charging and discharging
hierarchical_section_title: Rechargeable battery / Charging and discharging
caption_attribution_description: English: Solar AA battery charger. Manufacturer recommends 2 to 3 hours for one battery, and up to 10 to 14 hours for 4 batteries. "Times will vary depending upon the strength of sunlight or the depth of discharge of the batteries." Made in China.
context_page_description: A rechargeable battery, storage battery, or secondary cell, is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or primary battery, which is supplied fully charged and discarded after use. It is composed of one or more electrochemical cells. The term "accumulator" is used as it accumulates and stores energy through a reversible electrochemical reaction. Rechargeable batteries are produced in many different shapes and sizes, ranging from button cells to megawatt systems connected to stabilize an electrical distribution network. Several different combinations of electrode materials and electrolytes are used, including lead–acid, zinc-air, nickel–cadmium, nickel–metal hydride, lithium-ion, Lithium Iron Phosphate, and lithium-ion polymer.
  Rechargeable batteries typically initially cost more than disposable batteries, but have a much lower total cost of ownership and environmental impact, as they can be recharged inexpensively many times before they need replacing. Some rechargeable battery types are available in the same sizes and voltages as disposable types, and can be used interchangeably with them.
context_section_description: During charging, the positive active material is oxidized, producing electrons, and the negative material is reduced, consuming electrons. These electrons constitute the current flow in the external circuit. The electrolyte may serve as a simple buffer for internal ion flow between the electrodes, as in lithium-ion and nickel-cadmium cells, or it may be an active participant in the electrochemical reaction, as in lead–acid cells.
  The energy used to charge rechargeable batteries usually comes from a battery charger using AC mains electricity, although some are equipped to use a vehicle's 12-volt DC power outlet.  The voltage of the source must be higher than that of the battery to force current to flow into it, but not too much higher or the battery may be damaged.
  Chargers take from a few minutes to several hours to charge a battery. Slow "dumb" chargers without voltage or temperature-sensing capabilities will charge at a low rate, typically taking 14 hours or more to reach a full charge.  Rapid chargers can typically charge cells in two to five hours, depending on the model, with the fastest taking as little as fifteen minutes.  Fast chargers must have multiple ways of detecting when a cell reaches full charge (change in terminal voltage, temperature, etc.) to stop charging before harmful overcharging or overheating occurs.  The fastest chargers often incorporate cooling fans to keep the cells from overheating. Battery packs intended for rapid charging may include a temperature sensor that the charger uses to protect the pack; the sensor will have one or more additional electrical contacts.
  Different battery chemistries require different charging schemes.  For example, some battery types can be safely recharged from a constant voltage source.  Other types need to be charged with a regulated current source that tapers as the battery reaches fully charged voltage. Charging a battery incorrectly can damage a battery; in extreme cases, batteries can overheat, catch fire, or explosively vent their contents.
caption: A solar-powered charger for rechargeable AA batteries
exif: {"Image Make": "NIKON CORPORATION", "Image Model": "NIKON D40X", "Image XResolution": "72", "Image YResolution": "72", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "GIMP 2.4.5", "Image DateTime": "2008:07:22 22:43:32", "Image ExifOffset": "188", "EXIF ExposureTime": "1/160", "EXIF FNumber": "16", "EXIF ExposureProgram": "Manual", "EXIF ISOSpeedRatings": "100", "EXIF DateTimeOriginal": "2008:07:22 22:06:34", "EXIF DateTimeDigitized": "2008:07:22 22:06:34", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "31/10", "EXIF MeteringMode": "Pattern", "EXIF LightSource": "Unknown", "EXIF Flash": "Flash did not fire", "EXIF FocalLength": "105", "EXIF SubSecTime": "10", "EXIF SubSecTimeOriginal": "10", "EXIF SubSecTimeDigitized": "10", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Manual Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "1", "EXIF FocalLengthIn35mmFilm": "157", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "None", "EXIF Contrast": "Hard", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal"}