AC (Alternating Current)
The type of power sent over the grid, available in your house, or inverted from DC. In the USA this is typically 110 or 220 volts
Accumulator
A rechargeable battery is technically called an accumulator.
AGM (Absorbed Glass Matt)
AGM, short for Absorbed Glass Matt. Refers to batteries manufactured by using a form of Fiberglass Matt sandwiched between the lead plates. This serves to Absorb the acid, making the battery highly leak proof, and adding to its durability
Ah (Amp hours)
Amp hour is a unit of measure for a battery\'s electrical storage capacity. The standard rating is an Amp rating taken for 20 Hours. What this means, say for a 100 AH rated battery is this: Draw from the battery for 20 hours and it will provide a total of 100 amps. That translates to about 5 amps an hour. 5 x 20 = 100. However, it\'s very important to know that the total time of discharge and load applied is not a linear relationship. As your load increases, your realized capacity decreases. This means if you discharged that same 100 AH battery by a 100 amp load, it will not give you one hour of runtime. On the contrary, the perceived capacity of the battery will be that of 64 Amp Hours.
Ambient Temperature
It is the average temperature of the surrounding medium of a battery. In general, higher temperatures tend to accelerate chemical reactions within the battery, which can lead to increased power output. However, if the temperature gets too high, it can cause the battery to overheat and become damaged. Conversely, low temperatures can slow down chemical reactions and reduce power output. Additionally, extremely cold temperatures can cause the battery fluid to freeze, which can damage the battery cells. As a result, it is important to take ambient temperature into account when operating a battery-powered device.
Anode
An anode is the negative terminal of a battery. It releases electrons to the load and thus performs reduction. This is the normal case where the battery discharges. If the battery is charging, the anode accepts electrons and acts as a positive terminal.
Battery
A battery is a group of two or more cells connected in a specific pattern(either series or parallel) that depends on the purpose. Thus the battery is used at larger power requirements. Read more on battery construction.
Bobbin Cell
This refers to one of the most basic cell designs where one electrode typically consists of a solid cylindrical core and the other electrode is an annular layer surrounding it. Such a cell has a relatively low electrode surface area, resulting in a lower power cell than other cell designs.
Boost Charge
Charging of batteries in storage to maintain their capacity and counter the effects of self-discharge.
Bottom Voltage
The bottom voltage is the lowest voltage on discharging, also known as cut-off voltage or end voltage on discharge.
Capacity
Battery capacity. The capacity of a battery refers to the amount of energy that it can store. This is typically measured in terms of the number of hours that the battery can power a particular device, such as a flashlight or a laptop. The capacity of a battery is affected by a number of factors, including its size, its chemistry, and its design. For example, batteries with a higher capacity will typically be larger in size than those with a lower capacity.
Cathode
A cathode is the positive terminal of a battery. It accepts electrons and thus performs oxidation. This is the normal case where the battery discharges. If the battery is charging, the cathode releases electrons to the load and acts as a negative terminal.
Cell
Representation of a cell. A cell is a single unit that stores electrical energy. It basically has positive and negative terminals and an electrolyte. When it is connected to a circuit, a chemical reaction happens through the terminals and the electrolyte to discharge electrical energy.
C5 or C Rate (Discharge or Charge current).
C-rate of a battery. C is a measure of the rate at which electrical current is drawn from a battery. C5 is the standard current of to discharge battery in 5 hours according to IEC standards. 1C5 stands for same value of current as capacity. 10C5 for a 10AH battery would be 100 amps, while 4C5 would be 40 amps, 0.5C5 stands for 5A. However, C5 is usually written as C to save time. Discharge or charge current, in amperes, expressed in multiples of the rated capacity.
Charge or Charging
The act of providing external electrical energy to a rechargeable battery (or cell), in order to reuse it multiple times. During charging, ions move through the electrolyte from the cathode to the anode.
Chemistry
Cells are classified based on the specific chemistry of the materials contained within. Common chemistries include variations of Lead, Nickel and Lithium metal. The chemistry dictates the cell voltage and the performance characteristics and each chemistry has its optimum charging algorithm; traditionally different battery chemistries are not interchangeable in the same charger. Each chemistry also possesses its own shipping, handling and disposal regulatory requirements.
Closed Circuit Voltage
Closed circuit voltage measured, when a battery or cell is under a load from an external source,also named end-voltage, cut-off voltage，
Constant Current Charge
It is the process of charging where the current is maintained constant throughout regardless of the voltage of a cell. Constant current charging is typically used for fast-charging applications, as it allows for a higher rate of charge than constant voltage charging.
There are several advantages to constant current charging, including improved safety and a lower risk of overcharging. However, it is important to note that constant current charging must be carefully monitored, as it can damage batteries if not done correctly.
Constant Voltage Charge
It is the process of charging where the voltage applied is maintained constant throughout regardless of the current drawn. This technique is often used for lead-acid batteries, as it helps to extend their lifespan by preventing them from being overcharged.
The main disadvantage of constant voltage charging is that it can take longer to charge a battery than other methods, such as constant current charging. However, this method is generally considered to be safer for both batteries and chargers, making it a good choice for many applications.
Corrosion
Battery Terminal Corrosion. Corrosion is the chemical process that leads to the degradation of battery terminals. Uncontrolled corrosion results in battery failure. To prevent corrosion in batteries, manufacturers use a number of different materials and coatings, such as zinc and chromate. However, even with these precautions, it is still important to regularly inspect batteries for signs of corrosion and to clean them if necessary.
Current
Current is the rate of flow of electrons. It is expressed in Ampere(A).
Cutoff Voltage
Cut-off voltage is the minimum voltage that a battery can be safely discharged to without damaging the battery. Cutoff voltage is also called End-of Discharge voltage. Most batteries have a cut-off voltage of around 2.5 volts per cell, which means that a battery must not be discharged below 2.5 volts multiplied by the number of cells in the battery.For example, a typical AA battery has three cells, so the cut-off voltage would be 2.5 x 3 = 7.5 volts. Once a battery is discharged below its cut-off voltage, the chemical reaction that generates electricity will stop and the battery will be unable to hold a charge. Therefore, it is important to ensure that batteries are never discharged below their cut-off voltage.
Cycle Life
A battery’s cycle life is the number of times it can be discharged and recharged before it reaches the end of its useful life. For most consumer applications, a battery’s cycle life is typically between 300 and 500 cycles. Lithium-ion batteries, however, can last up to 1,500 cycles. The cycle life of a battery is directly related to its depth of discharge (DoD).
Number of cycles vs Depth of discharge of a battery
Number of cycles vs Depth of discharge of a battery
For example, a battery with a 50% DoD will have twice the cycle life of a battery with a 100% DoD. In general, the shallower the discharge, the longer the cycle life.
Deep Cycle
A battery’s deep cycle refers to its ability to be repeatedly discharged and recharged without damaging the battery. The depth of discharge (DOD) is the measure of how much charge has been used relative to the battery’s full capacity.For example, if a 100 amp-hour (Ah) battery is discharged by 50 amps, the DOD would be 50%. A battery that can withstand many deep cycles will have a high DOD.
Depth of Discharge (DOD)
The percentage of the battery that has been discharged relative to the overall capacity of the battery. Learn more here.
Direct Current (D.C.)
Electric flow is of Direct current in circuit.; electric charge only flows in one direction.
Discharge or Discharging
Discharging is the process in which the battery releases its electrical energy to the circuit.
Electron
An electron is a negatively charged particle in an atom. It revolves around the nucleus of the atom. The electrons are released, acquired, or shared during the chemical reactions.
Electrode
An electrode is a conductor through which electrons flow in a cell to produce electric energy. Every cell has a positive and negative electrode.
Electrolyte
An electrolyte is a solution of chemical compounds that facilitates ions to react with cathode and anode.
Energy
It is basically the amount of power released. In the case of a battery, the energy is the amount of electrical energy released. The equation to find the energy of a cell is E = Voltage x Discharge Rate x Discharge Time. Cell energy is usually expressed in milli-Watt hours (mWh).
Energy Density
Energy density is the volumetric estimation of energy stored in a battery. It is the ratio of cell energy to its volume. There are several factors that contribute to the energy density of a battery, including the type of electrodes used, the electrolyte used, and the size and shape of the cell.
Gassing
The evolution of gas from one or more of the electrodes in a cell. Gassing commonly results from local action (self-discharging) or from the electrolysis of the electrolyte during charging.
Impedance
The impedance of a cell is a complex quantity that refers to the resistance to flow of an Alternating Current (AC) through a cell. It includes the DC resistance as well as capacitance and inductance, which change with frequency.
Intelligent battery
Battery with internal circuit enabling some communication between the battery and user. Some batteries feature a capacity indicator only, others offer an external bus to interface with the equipment, the battery powers, and the intelligent charger.
Internal Resistance
Internal resistance is the resistance offered by the ionic and electronic components of the cell. Internal resistance can be decreased by using higher quality materials in the construction of the battery, and by keeping the battery’s internal components cool.
Load (on-load or off-load)
A term used to define the current drain on a battery based on the resistance of any device connected to it. Internal battery resistance and depleting state-ofcharge cause the voltage to drop.
Current Limited (the limited current)
The limited current refers to the maximum amount of current that can be drawn from a battery without damaging it. This limit is set by the battery’s internal resistance, which regulates the flow of current between the battery’s positive and negative terminals.
When the limiting current is exceeded, the battery’s internal resistance increases, causing the battery to overheat and potentially explode.
mA
1/1000th of an amp. or, 1 amp equals 1000 milliamps
mAh
1/1000th of an amp hour. or, one of standard unites of capacity.
Memory Effect
Some cell chemistries (like Ni/Cd) require the cell to be fully discharged before being recharged in order to maintain their discharge capacities. If this is not done, the capacity from cycle to cycle diminishes fairly rapidly.
Nominal Voltage (also named Rated Voltage)
The voltage of a battery midway in the discharge between the fully charged state and the end voltage at which a battery spends most of its time on the discharge curve.
Open Circuit Voltage (OCV)
Voltage measurement where the battery or cell is under no load from an external source.
Operating Temperature
The temperature at which a battery operates. The battery will operate effectively within a specified temperature range which varies based on the battery’s function and application purposes. If the battery is used outside of this range, the application may fail prematurely.
Overcharge (over-charge,over-charging)
Charging beyond the maximum, safe capacity limit of a cell or battery. This typically has very negative consequences depending on the cell chemistry, hence must be avoided.
Over Discharge (over discharge,over-discharge,over-discharging)
Discharge past the point where the full capacity of the cell battery has been obtained. This can also lead to undesirable situations
Parallel Pack/Battery
Cells are connected in parallel to increase the capacity of a battery pack. The positive terminals of all cells are connected together (or to a common conductor), while the negative terminals of all cells are connected in a similar fashion. The battery pack capacity will be the sum of all cell capacities combined, while the pack voltage will be the voltage of one cell.
Peak Current
The top amperage of your lithium battery on charging and discharging.
Peak Voltage (cut-off or end voltage on charging)
The highest voltage of on charging, also known as cut-off voltage or end voltage on charging.
Protective Circuit
Electrical circuit built into a battery pack to ensure safety under all operational/ environmental circumstances; preventing abuses such as excessive current, operation at extreme temperatures, overcharge and over-discharge.
Oxidation
The chemical reaction that results in the release of electrons is known as oxidation.
Primary Cell
Non-rechargeable cells are called primary cells. The alkaline and zinc-carbon cells are primary cells.
Rated Capacity
The Number of Ampere-hours a battery can deliver under specific conditions (rate of discharge, end voltage, temperature); usually the manufacturer’s rating.
Reduction
The chemical reaction that acquires electrons is known as reduction.
Secondary Cell
Secondary cells are rechargeable cells. Most devices including mobile phones use secondary cells.
Self-Discharge
When batteries are unused for a long period, the amount of energy that a battery can store begins to decline, and eventually, it will no longer be able to power devices. One way to prolong the life of a battery is to keep it stored in a cool, dry place. This will slow down the self-discharge process and allow the battery to be used for a longer period of time. Another way to reduce self-discharge is to use devices that are designed specifically for low-power applications. These devices draw less current from the battery, which reduces the amount of energy that is lost over time
Separator
The separator is insulation in the cell that keeps the anode and cathode separate.
Series Pack Configuration
Cells are connected in series to increase the voltage of the battery pack. The positive terminal of the first cell in the series is connected to the negative terminal of the second cell in the series and so on. The voltage of the battery pack is the sum of all cell voltages, while the capacity of the battery pack will be the lowest capacity cell in the series.
Service Life
Service life is the useful lifetime of a battery until it hits its cutoff voltage.
Shelf Life
The shelf life of a battery is the maximum duration in which the battery can be stored in the preferable conditions so that it retains its performance when used.
Smart Battery
A Smart Battery is a rechargeable battery pack incorporating a Battery Management System (BMS) with an external communication data bus (usually a 2-wire system called SMBus). The BMS protects the battery from operating outside its safe limits by monitoring key cell parameters (current, voltage, temperature, cycle count, state of charge, etc.) in a single or multi-cell pack, performing cell balancing to ensure optimum performance, battery authentication, as well as external communication of the battery health data with a smart charger and/or host device through the SMBUS.
Specific Energy
It is the amount of energy that can be stored in a battery per unit of mass (in units of watt-hours per kilogram, or Wh/kg). The higher the specific energy, the more energy a battery can store for a given mass.
Spirally Wound Cell
A cylindrical cell which uses an electrode structure made by winding electrode sheets or ribbons separated by a separator, into a cylindrical “jelly roll” construction in order to increase the electrode surface area and provide a higher rate cell compared to a bobbin cell.
State of Charge (SOC)
The available capacity at any given time in a battery expressed as a percentage of rated capacity.
State of Health (SOH)
While there is no standard definition for this, it generally refers to how a cell or battery is performing in relation to its design expectation. The impedance is one way to report the state of health.
Temperature Effects
Battery life dramatically shortens when operated at extreme high or low temperatures. High temperatures increase internal cell pressure, which can result in leaks or other cell integrity issues. Low temperatures can increase internal resistance which produces heat. This heat can cause the electrolyte to evaporate in a non-hermetic system, hence reduces capacity.
Thermal Runaway
A condition whereby a battery on charge or discharge will overheat in an uncontrolled manner due to internal chemical reactions triggered upon reaching a threshold due to overcharge or over-discharge or other electrical or mechanical abuse.
Trickle Charge
Trickle charge is a low-rate charging of a battery with a constant-current supply to maintain the battery in a fully charged condition.
Terminals
A battery is connected to an external circuit at its terminals. Every battery has a positive and negative terminal.
Voltage Delay
Time delay for a battery to deliver the required operating voltage after it is placed under load. Typically a voltage depression followed by a recovery will be observed when this phenomenon is present.
Voltage Depression
An abnormally low voltage, below the expected value, during the discharge of a battery. Sometimes seen in extremely low temperatures (typically < - 20°C).
Voltage Drop
A voltage drop is a net difference in potential when measured across two ends of a conductor. It is expressed in volts (V).
Working Voltage (also named Rated Voltage)
The typical voltage or range of voltages of a battery during discharge, also professional called middle point of discharge platform.
Watt Hours (Wh)
Power output in limited standard time, 1hour. Watt hours (Wh) is unit of energy that measure the capacity of power (watts) moving over time.
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