Rechargeable battery

Rechargeable batteries are produced in many different shapes and sizes, ranging from button cells to megawatt systems connected to stabilize an electrical distribution network.

[1][2][3] Devices which use rechargeable batteries include automobile starters, portable consumer devices, light vehicles (such as motorized wheelchairs, golf carts, electric bicycles, and electric forklifts), road vehicles (cars, vans, trucks, motorbikes), trains, small airplanes, tools, uninterruptible power supplies, and battery storage power stations.

Emerging applications in hybrid internal combustion-battery and electric vehicles drive the technology to reduce cost, weight, and size, and increase lifetime.

Battery storage power stations use rechargeable batteries for load-leveling (storing electric energy at times of low demand for use during peak periods) and for renewable energy uses (such as storing power generated from photovoltaic arrays during the day to be used at night).

Heavy-duty batteries power electric vehicles, ranging from scooters to locomotives and ships.

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.)

For lead-acid cells, the relationship between time and discharge rate is described by Peukert's law; a lead-acid cell that can no longer sustain a usable terminal voltage at a high current may still have usable capacity, if discharged at a much lower rate.

Many battery-operated devices have a low-voltage cutoff that prevents deep discharges from occurring that might cause cell reversal.

If a multi-cell battery is fully discharged, it will often be damaged due to the cell reversal effect mentioned above.

An example of this is the sulfation that occurs in lead-acid batteries that are left sitting on a shelf for long periods.

Since damage may also occur if the battery is overcharged, the optimal level of charge during storage is typically around 30% to 70%.

Due to variations during manufacture and aging, the DOD for complete discharge can change over time or number of charge cycles.

[10] If batteries are used repeatedly even without mistreatment, they lose capacity as the number of charge cycles increases, until they are eventually considered to have reached the end of their useful life.

Sealed batteries may lose moisture from their liquid electrolyte, especially if overcharged or operated at high temperature.

For some types, the maximum charging rate will be limited by the speed at which active material can diffuse through a liquid electrolyte.

Very roughly, and with many exceptions and caveats, restoring a battery's full capacity in one hour or less is considered fast charging.

Although this convention is sometimes carried through to rechargeable systems—especially with lithium-ion cells, because of their origins in primary lithium cells—this practice can lead to confusion.

The nickel–iron battery (NiFe) was also developed by Waldemar Jungner in 1899; and commercialized by Thomas Edison in 1901 in the United States for electric vehicles and railway signalling.

It is composed of only non-toxic elements, unlike many kinds of batteries that contain toxic mercury, cadmium, or lead.

The lithium-ion battery was introduced in the market in 1991, is the choice in most consumer electronics, having the best energy density and a very slow loss of charge when not in use.

[13] Such incidents are rare and according to experts, they can be minimized "via appropriate design, installation, procedures and layers of safeguards" so the risk is acceptable.

LiPo packs are readily available on the consumer market, in various configurations, up to 44.4 V, for powering certain R/C vehicles and helicopters or drones.

[19] Independent reviews of the technology discuss the risk of fire and explosion from lithium-ion batteries under certain conditions because they use liquid electrolytes.

UltraBattery, a hybrid lead–acid battery and ultracapacitor invented by Australia's national science organisation CSIRO, exhibits tens of thousands of partial state of charge cycles and has outperformed traditional lead-acid, lithium, and NiMH-based cells when compared in testing in this mode against variability management power profiles.

The potassium-ion battery delivers around a million cycles, due to the extraordinary electrochemical stability of potassium insertion/extraction materials such as Prussian blue.

Ultracapacitors – capacitors of extremely high value – are also used; an electric screwdriver which charges in 90 seconds and will drive about half as many screws as a device using a rechargeable battery was introduced in 2007,[47] and similar flashlights have been produced.

[48] Ultracapacitors are being developed for transportation, using a large capacitor to store energy instead of the rechargeable battery banks used in hybrid vehicles.

Rechargeable battery research includes development of new electrochemical systems as well as improving the life span and capacity of current types.