By passing an electric current through a battery, a battery charger, also known as a recharger, stores energy. The size and kind of the battery being charged determines the charging process (how much voltage or current to use, for how long, and what to do when charging is finished). Depending on the battery type, some battery types can be recharged by connecting to either a constant voltage source or a constant current source and have a high tolerance for overcharging (i.e., continuing charging after the battery has been fully charged). At the conclusion of the charging cycle, simple chargers of this kind must be manually detached. Other battery types utilize a timer to stop the charging process when it should be finished.
Other battery types can explode, become damaged (lower capacity, reduced lifetime), overheat, or become damaged (reduced capacity). In order to securely adjust the charging current and voltage, ascertain the status of charge, and switch off at the end of charge, the charger may include temperature or voltage sensing circuits and a microprocessor controller.
To account for wire resistance, chargers may increase the output voltage proportionally to the current.
A trickle charger delivers a negligibly small amount of electricity, just enough to prevent a battery's long-term self-discharge. Trickle charging is incompatible with some battery types, and attempting to do so risked damaging them. Lithium-ion batteries are unable to withstand continuous trickle charging.
Longer charging times are possible with slow battery chargers. High-rate chargers may recover the majority of capacity considerably more quickly, but they may be too much for some battery types to handle. To prevent overcharging with such batteries, the battery must be actively monitored. High-rate chargers are preferably required for electric automobiles. Installation of these chargers and the distribution support for them constitute a problem for public accessibility in the projected use of electric cars.
C-rate
A measure of the rate at which a battery is charged or discharged relative to its capacity, charge and discharge rates are sometimes expressed as C or C-rate. The charge or discharge current divided by the battery's ability to store electrical charge is known as the C-rate. The C-rate is expressed in the unit h1, which is comparable to expressing the battery's ability to hold an electrical charge in the same unit of hour times current as the charge or discharge current. The context determines whether the C-rate refers to a charging or discharging process because it can never be negative.
For instance, a discharge rate of 5000 mA (or 5 A) for a battery with a capacity of 500 mAh equates to a C-rate of 10C, which means that such a current may deplete 10 of these batteries in an hour. A charge current of 250 mA for the same battery also equates to a C-rate of C/2, which means that this current will raise the battery's state of charge by 50% in an hour.
The capacity of a battery to hold a charge, which is represented by the SI unit coulomb with the unit sign C, should not be confused with the unit of the C-rate because it is often implied.
The C-rate ratio becomes a ratio of the (dis)charge power to the battery's energy capacity if the battery voltage is multiplied by both the (dis)charge current and the battery capacity. For instance, the C-rate of the 100 kWh battery in a Tesla Model S P100D is 1.2C when the battery is being supercharged at 120 kW, and it is 4.51C when the battery is operating at its maximum output of 451 kW.
Internal heat is produced by all battery charging and discharging, and the amount produced is roughly inversely proportionate to the current involved (a battery's present state of charge, condition, history, etc. are other considerations). Cooling may be seen as some batteries charge to capacity. The construction of battery cells that permit higher C-rates than typical must account for additional heating. However, high C-rating batteries are desirable to end consumers since they can be charged more quickly and deliver greater current when in use. In order to avoid overcharging and subsequent cell damage at high C-rates, the charger is often required to closely monitor battery characteristics including terminal voltage and temperature.
Only some battery types allow for such rapid charging rates. Others risk being hurt, overheating, or even catching fire. Some batteries could potentially blow up. [Reference needed] For instance, there are various explosive risks associated with lead-acid automobile SLI (starting, lighting, ignition) batteries.
Type
Simple charger
A straightforward charger charges a battery by feeding it with a steady DC or pulsed DC power source. The output of a simple charger normally isn't affected by the battery's charge or charging time. A simple charger is inexpensive due to its simplicity, yet there are drawbacks. A skillfully constructed basic charger typically requires more time to charge a battery because it is programmed to use a slower (i.e., safer) charging rate. Even so, many batteries overcharged when placed on a standard charger for an excessively long time will become weak or irreparably damaged. Another difference between these chargers is that they can give the battery either a constant voltage or a constant current.
Due to their low-cost design and construction, simple AC-powered battery chargers typically have ripple current and voltage values that are substantially higher than those of other battery charger types. The ripple voltage will typically be well within the suggested level when the ripple current is within the battery's manufacturer's recommended range. A common 12 V 100 Ah VRLA battery has a maximum ripple current of 5 amps. The anticipated life of a ripple-charged VRLA battery will be within 3% of the life of a constant DC-charged battery as long as the ripple current is not high (more than 3 to 4 times the level advised by the battery manufacturer).
Fast charger
Control circuitry is used by fast chargers to charge batteries more quickly while preventing cell damage. The control circuitry may be integrated into the battery (often for each cell) or in the external charging device, or it may be distributed between the two. To help keep the temperature of the batteries at safe levels, the majority of these chargers incorporate cooling fans. When used with common NiMH cells that lack the particular control electronics, the majority of fast chargers can also function as regular overnight charges.
Three stage charger
An intelligent charger uses a 3-stage charging strategy and makes an effort to determine the battery's condition and level of charge in order to shorten the charging time and provide continuous charging. The description that follows is based on a sealed lead acid traction battery operating at 25 °C. Bulk absorption is the first stage of charging, during which the charger's capacity determines how high and steady the charging current can be held. The charger moves to the second stage and maintains the voltage when the battery voltage reaches the outgassing level (2.22 volts per cell) (2.40 volts per cell).
When the provided current is less than 0.005C, the charger enters its third stage, and the output is held constant at 2.25 volts per cell. The delivered current will decrease while the voltage is maintained. The battery may be kept fully charged and self-discharge compensated at this voltage in the third stage because the charging current is relatively low (0.005C).
Induction-powered charger
Batteries are charged using electromagnetic induction by inductive battery chargers. Through inductive coupling, a charging station transmits electromagnetic energy to an electrical device, which stores the energy in the batteries. No metal contacts between the charger and battery are required for this to work. Electric toothbrushes and other bathroom accessories typically employ inductive battery charges. There is no danger of electrocution because there are no open electrical contacts. It is now employed to recharge wireless phones.
Smart charger
Smart chargers can adapt their charging settings to a battery's condition in contrast to "dumb" chargers, which may deliver a constant voltage through a preset resistance. It should not be confused with a smart battery, which has a computer chip and digitally connects with a smart charger to determine the state of the battery. A smart charger is necessary for a smart battery (see Smart Battery Data).
Even "dumb" batteries, which have no internal electronics, can be charged by some smart chargers.
The status of the battery affects a smart charger's output current. An intelligent charger can decide the best charge current or stop charging by keeping an eye on the battery's voltage, temperature, and charge time.
The voltage of Ni-Cd and NiMH batteries gradually rises throughout the charging process until the battery is fully charged. A smart charger can know the battery is fully charged when the voltage starts to drop after that. These chargers frequently include labels that read "V," "delta-V," or occasionally "delta peak," which denote that they track voltage variation. Even a smart charger could be affected by this and keep charging even after the batteries are completely charged. The batteries may be overcharged as a result. To avoid overcharging, many intelligent chargers use a variety of cut-off mechanisms.
Motion-powered charger
Devices that recharge batteries with energy from human motion, such as walking, are now being produced by a number of firms. One produced by Tremont Electric has a magnet that can charge a battery as it is pushed up and down that is held between two springs. Such goods haven't yet seen a lot of market success.
A mobile phone charger that fits into tables and is pedal-powered has been developed for installation in public areas including airports, train stations, and universities. They have been put in place in numerous nations across several continents.
Pulse charger
Some chargers feed the battery a sequence of electrical pulses using pulse technology. The rising time, pulse width, frequency, and amplitude of the DC pulses are all tightly regulated. Any size and kind of battery, including automotive and valve-regulated ones, can be used with this technology.
High instantaneous voltages are applied during pulse charging without overheating the battery. This considerably increases the battery's useful life by dissolving lead-sulfate crystals in lead-acid batteries.
There are numerous patents for pulse charger types.
Open source hardware is another type.
Solar charger
When the charger is first attached, some chargers use pulses to determine the battery's current state before using constant current charging for fast charging and pulse mode for trickle charging.
Negative pulse charging, often known as reflex charging or burp charging, is a technique used by some chargers. Both positive and brief negative current pulses are used by these chargers. Negative pulse charging is not much superior to regular pulse charging in terms of effectiveness.
Light energy is transformed into low voltage DC current by solar chargers. They can be fixed mounted but are typically movable. Solar panels are another name for fixed mount solar chargers. While portable solar chargers are used off-grid, these are frequently connected to the electrical grid via control and interface circuits (i.e. cars, boats, or RVs).
Timer-based charger
Even though portable solar chargers only use energy from the sun, some of them have the ability to charge in dim light (like at dusk). Even while some of these devices can fully recharge batteries, portable solar chargers are frequently used for trickle charging.
A timed charger's output is cut off after a specific amount of time. In the late 1990s, timer chargers were the most popular form for charging low-capacity consumer Ni-Cd batteries.
Trickle charger
Frequently, a timer charger and set of batteries can be purchased together, and the charger time is specially configured for those batteries. Batteries with smaller capacity would be overcharged if charged, whereas batteries of higher capacity would not charge fully if timer-charged.
Timer-based chargers also had the issue of overcharging batteries when used on partially drained batteries.Low-current devices, such as trickle chargers, typically have currents of 5 to 1,500 mA. They are typically used to charge batteries with small capacities (2-30 Ah). In automobiles and boats, they are also used to maintain batteries with greater capacities (> 30 Ah). The battery charger's current is only adequate to produce trickle current in larger applications. The trickle charger may be left attached to the battery indefinitely depending on its technology. Certain battery types should not be charged slowly. For instance, the majority of Li-ion batteries cannot be trickle charged properly and may ignite or explode.
Universal battery charger–analyzer
In crucial applications, the most complex chargers are utilized (e.g. military or aviation batteries). These powerful automatic "intelligent charging" devices can be programmed to perform intricate charging cycles that the battery producer specifies. The best have automatic capacity testing and analysis features and are universal (can charge any battery kinds).
USB-based charger
A USB cable can be used to connect a device to a power source because the Universal Serial Bus protocol offers five-volt power. Products based on this methodology include tablet computers, portable digital audio players, and cell phone chargers. They could be unmanaged, straightforward chargers or fully compliant USB peripherals.
Power bank
A portable device known as a power or battery bank can provide energy and power from its internal battery, usually through a USB connector.
Different sizes of power banks are commonly made up of 18650 battery cells. The tiniest power banks just have one cell. Smaller ones for mobile phones typically have a parallel circuit of a few cells, while larger ones also include two series circuits.
In addition to being used as a power source for different USB-powered accessories like lights, small fans, and external digital camera battery chargers, power banks are popular for charging smaller battery-powered devices with USB connections like mobile phones and tablet computers. They typically use a USB power source to recharge. The USB-C port is used by more current power banks, which may also have a USB-B micro port for older devices.
A control circuit is built inside the power bank, which regulates battery charging and changes the battery voltage to 5.0 volts for the USB connection.
It's possible for power banks to recognize a connection and turn on automatically.
A power bank may shut down automatically if the current load falls below a model-specific threshold for a predetermined amount of time.
Four LED lamps for each quartal are commonly used to indicate the charging state, while some higher-end models have an accurate percentage display.
Some power banks have the ability to transmit electricity wirelessly, some contain an LED lamp for momentary close-range lighting when required, and some have a pass-through charging function that enables transferring power through their USB ports while still charging them.
For devices that require more power, including laptop computers, some larger power banks incorporate DC connectors (also known as barrel connectors).
Battery cases
Small power banks known as battery cases are fastened to the back of a phone like a case. Wirelessly or using the USB charging ports, power can be transmitted.
As was the case for the Nokia Lumia 1020, battery cases are also available in the shape of a camera grip accessory.
Extended batteries are available for mobile phones with removable rear covers. These internal batteries are larger and are connected with an upgraded, more roomy back cover in place of the standard one. Incompatibility with other phone cases while attached is a drawback.
Applications
It is more cost-effective to manufacture battery chargers without voltage regulation or DC voltage output filtering because they are designed to be connected to batteries. Battery eliminators are also used to refer to battery chargers with voltage regulation and filtration.
Battery charger for vehicles
There are primarily two types of chargers for automobiles:
A modular charger, usually a 3-stage charger, is used to recharge the starter battery of a fuel-powered vehicle.
To recharge the battery pack of an electric vehicle (EV); see Charging station.
Car battery chargers come in a variety of ratings. Maintaining charge on parked vehicle batteries or small batteries in garden tractors or other similar equipment is possible using chargers with a two-amp rating. For car battery maintenance or to recharge a battery that has unintentionally discharged, a driver may have a charger with a few amperes to ten or fifteen amperes rating. Large chargers may fully charge a battery in an hour or two at service stations and commercial garages; frequently, these chargers can temporarily provide the hundreds of amps needed to crank an internal combustion engine starting.
Electric vehicle batteries
Battery chargers for electric vehicles (ECS) are available in a wide range of manufacturers and features. The maximum charge rate for these chargers ranges from 1 kW to 7.5 kW. Others use constant voltage and constant current, while some employ algorithm charge curves. Some include dials for maximum voltage and amperage, some are preset to specific battery pack voltage, amp-hour, and chemistry, and some are programmable by the end user via a CAN interface. The range of prices is $400 to $4500.
With a 1 amp charger, a 10 amp-hour battery could take 15 hours to fully charge from a fully depleted state because it would need nearly 1.5 times the battery's capacity.
6 kW is offered via public EV charging stations (host power of 208 to 240 VAC off a 40 amp circuit). An EV may be recharged at 6 kW nearly six times faster than at 1 kW while charging overnight.
The only factors that can affect how quickly batteries can be recharged are the type of battery, the type of charging method, and the amount of available AC power.
To recharge the EV's battery, onboard EV chargers (which convert AC power to DC power) include:
Isolated: They don't physically link the batteries that are being charged to the A/C electrical mains. These frequently use an inductive connection of some kind between the grid and a charging car. It is possible to use some isolated chargers in concurrently. This enables a higher charge current and quicker charging. There is a maximum current rating for the battery that cannot be exceeded.
Non-isolated: The battery charger's wiring is directly connected to that of the A/C outlet. Chargers that are not isolated cannot be used in parallel.
Charge times can be shortened by using power-factor correction (PFC) chargers, which can produce current near to the maximum allowed by the plug.
Charge stations
Before declaring bankruptcy in May 2013, Project Better Place was building a network of charging stations and covering the cost of car batteries via leases and credits.
Induction-powered charging
The Online Electric Vehicle (OLEV) is an electric transportation system that was developed by researchers at the Korea Advanced Institute of Science and Technology (KAIST). The OLEV uses inductive charging, in which a power source is placed beneath the road's surface and power is wirelessly picked up by the vehicle.
Mobile phone charger
The majority of mobile phone chargers are actually just power adapters that supply power to the charging circuitry, which is almost typically built inside the mobile phone itself. Older phones are infamous for being extremely diverse, with a wide range of DC connector types and voltages, the majority of which are incompatible with phones from other manufacturers or even various versions of phones from the same manufacturer. Some more expensive variants come with numerous connectors and a monitor that shows output current. Some devices feature charging parameter communication protocols as Qualcomm Quick Charge or MediaTek Pump Express.
In order to ensure compatibility, chargers for "12V" automobile auxiliary power outlets may handle input voltages of up to 24 or 32 Volts (direct current) and come with a display to track the current or voltage of the car's electrical system.
China, the European Commission, and other nations are creating a national standard for USB-powered mobile phone chargers. For all data-enabled mobile phones sold in the EU, a single External Power Supply (EPS) with a microUSB connector will be developed and supported, according to a Memorandum of Understanding signed in June 2009 by ten of the top mobile phone manufacturers in the world. The International Telecommunication Union unveiled a standard for a mobile phone charger on October 22, 2009. (Micro-USB).
Very large standby battery banks (placed in battery rooms) may be used in telecommunications, electrical, and computer uninterruptible power supply facilities to support essential loads for several hours during outages of primary grid power. Such chargers have redundant independent power sources and redundant rectifier systems, as well as temperature correction, supervisory warnings for various system defects, and permanent installation. The charger can supply the direct current (DC) system load when the battery is detached for repair if chargers for stationary battery plants have proper voltage regulation, filtration, and current capacity. The charger's capacity is designed to support the system load while recharging a fully drained battery in, say, eight hours or various time frames.
Prolonging battery life
Batteries can attain their maximum cycle life with the use of a charger that is appropriately constructed. Excessive charging current, protracted overcharging, or cell reversal in a multiple cell pack harm cells and reduce battery life.
Lithium-ion batteries are used in the majority of contemporary cell phones, laptop and tablet computers, and electric vehicles.
These batteries last the longest if they are often charged; fully draining the cells would reduce their capacity rather quickly, but the majority of such batteries are used in equipment that can detect when it is about to reach full discharge and stop operation.
Batteries can attain their maximum cycle life with the use of a charger that is appropriately constructed. Excessive charging current, protracted overcharging, or cell reversal in a multiple cell pack harm cells and reduce battery life.
Lead-acid batteries have been used in a variety of motorized vehicles, including boats, RVs, ATVs, motorcycles, cars, and trucks. Although sulfation (a chemical reaction in the battery that deposits a coating of sulfates on the lead over time) will occur, these batteries use a sulfuric acid electrolyte and can typically be charged and drained without exhibiting memory effect. Usually, sulfated batteries are just swapped out for new ones, and the old ones are discarded. When a maintenance charger is used to "float charge" a lead-acid battery, the battery's lifespan will be significantly extended. This stops the battery from ever having a charge lower than 100%, which stops sulfate from developing. To get the best results, the right temperature-compensated float voltage should be applied.
Lithium battery cells decay more quickly at full charge than at 40–50% charge when they are stored after charging. As with other battery types, depreciation happens more quickly in hotter environments. Increased internal battery resistance, frequently brought on by cell oxidation, is what leads to lithium-ion battery degradation. As a result, the battery's efficiency falls, lowering the amount of net current that can be pulled from it. [Reference needed] Li-ION batteries now frequently feature "electronic fuses" that permanently disable them if the voltage drops below a predetermined threshold because if Li-ION cells are discharged below a particular voltage, a chemical reaction takes place that makes them deadly if refilled.
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