Batteries, accumulators, chargers - glossary of terminology

accumulator

An electrochemical device capable of converting electrical energy into chemical energy (charging) and, by reversing the process, of releasing electrical energy stored in the form of chemical energy (discharge). It consists of one or more (battery) electrochemical cells.

Ampere [A]

A unit of measurement for the intensity of an electric current.

amp-hours [Ah]

The product of the current (measured in amperes) by the length of time (in hours) that the battery is able to supply current at that amperage. Ampere-hours are usually the capacity of batteries/accumulators - according to the definition, a battery with a capacity of 1Ah is able to provide current of 1A for an hour, current of 0.5A for two hours, etc.

anode

A positive electrode on which the oxidation process takes place in a liquid solution - anions (negative ions) are released. In the case of rechargeable batteries, depending on the direction of current flow (charging or discharging process), each of the two electrodes can act as an anode, respectively. The negative electrode is the anode during discharge.

battery

In everyday language, it means one or more galvanic (electrochemical) cells electrically connected (in series, parallel), enabling the connection of other electrical devices to them.

Alkaline battery

A battery in which an alkaline (alkaline) solution is used as an electrolyte. The most popular electrolyte of this type is potassium hydroxide. These batteries do not contain mercury or cadmium.

primary battery

A battery that can only be used once. It is impossible to subject it to the process of charging in order to reverse the chemical reactions by which electricity was obtained from it. Examples of primary batteries are zinc-carbon and alkaline batteries. The opposite of a primary battery are rechargeable batteries (secondary batteries), in which the chemical processes that occur during the discharge (use) of the battery are reversible.

secondary battery

see battery

CC/CV

CC - constant current, CV - constant voltage - terms describing the basic phases of charging lithium-based batteries. For a typical 3.7V Li-ion battery, charging begins with a constant CC charging phase. The battery is charged with a constant current until the final voltage is reached - usually 4.20V. When the final voltage is reached, the current begins to decrease and the charging process enters the CV phase - constant voltage charging. Charging ends when the current drops to a certain (usually 50-150 mA) value. The current at which the charge ends is called the termination current.

External factors

Factors that may affect the performance and battery life - such as temperature, humidity, vibration, shock, etc.

cycle

In batteries, a single sequence of charging and discharging (using) processes of a battery.

Storage Time

The time for which the battery can be stored without irreversible loss of its properties. The length of this time depends on how quickly the self-discharge processes occur in the battery.

memory effect

A highly controversial phenomenon that supposedly occurs in some types of batteries (e.g. nickel-cadmium). It would consist in a decrease in the capacity of the battery in the event that its duty cycle has been completed with incomplete discharge.

positive electrode

An electrode that accepts electrons during the process of discharging (using) the battery.

negative electrode

An electrode that provides electrons during the process of discharging (using) the battery.

energy

Next to the capacity, it is a value that determines the performance of the battery. In order to measure it, it is necessary to take all the stored energy from a full battery/battery (it is necessary to carry out the discharge process). The energy stored in the battery is usually measured in watt-hours [Wh]. Battery with energygii 1Wh is able to deliver 1W power for an hour, 0.5W power for two hours, etc. The value of stored energy [Wh] in relation to the capacity [Ah] is more complementary and useful for assessing the performance of a given battery, because it takes into account the voltage value from the entire discharge waveform.

electrolyte

A substance that allows ions to move within an electrochemical cell. energy density A quantity characteristic of a given electrochemical system, measured in [Wh/m3]. It determines the amount of energy that a battery is able to store per unit volume.

cathode

The negative electrode on which the reduction processes take place, i.e. cations (positively charged ions) accept electrons (negative charges). In batteries, each of the electrodes can function as a cathode, depending on the direction of the current. The positive electrode is the cathode during normal battery operation (discharging).

Loading

A process in which externally supplied electricity is converted into chemical energy stored in a battery.

trickle charging

The process that most chargers subject batteries to when they have finished charging to full capacity, counteracting the natural tendency for the battery to self-discharge. In the case of popular rechargeable batteries (Ni-Cd, Ni-MH), it is charging with a very low current.

charger

A device that provides electricity to batteries in the charging process.

milliwatt-hours [mWh], watt-hours [Wh]

Units that determine the electrical energy that a given battery or accumulator is able to accumulate. Unlike a unit of capacity expressed in milliamp-hours/amp-hours, the energy value takes into account the breakdown of the output voltage of a given battery, so energy values can be compared between each power source.

tension

Measured in volts [V], the potential difference between the battery electrodes. In the case of cells, it depends on the electrochemical system of the cell. In the case of batteries consisting of several cells, also on the type of electrical connections between individual cells (series, parallel).

End Voltage

The voltage at which the process of discharging or charging the battery or accumulator is completed. In the case of lithium batteries, it means the final voltage to which the cell is charged in the CV phase. Once this voltage is reached and stabilized, the charger should stop charging.

Termination Voltage

See End Voltage.

electrochemical cell

The smallest unit included in a battery - consists of a positive and negative electrode, a separator and an electrolyte. It stores electricity in chemical form. The capacity of a cell depends on its size, while the cell voltage depends on the electrochemical type of the cell. All cells are capable of converting chemical energy into electricity, some (batteries) are also capable of converting the electrical energy supplied to them into chemical energy (charging).

Capacity (C)

Value indicating the performance of the battery/accumulator. The only method of determining capacity is to take all stored capacity from a full battery/battery (a discharge process is required). Battery capacity is usually measured in ampere-hours [Ah]. A 1Ah battery is able to supply 1A for an hour, 0.5A for two hours, etc. The charge/discharge current for batteries is often expressed in multiples of C - e.g. the current of 0.1C for a battery with a capacity of 1.4Ah (1400mAh) is 140mA.

Charging termination current

A term characteristic of lithium-based batteries. Specifies the minimum charging current that the lithium cell is charged when it reaches its final voltage in the constant voltage (CV) charging phase.

internal resistance

In batteries and accumulators, it determines the cell's own resistance. Each rechargeable battery works to some extent like a standard resistork-resistor, where the current flowing through them causes the voltage drop. The larger the battery, the greater the voltage drop it causes and, as a result, less current can flow through it for the target device. A battery with a higher resistance generates a higher voltage drop at the terminals when discharging - according to Ohm's basic law. An increase in internal resistance is a natural phenomenon of the wear and tear of batteries and batteries. This is a very negative phenomenon, as it very often leads to premature and unexpected shutdown of the device. Energy losses related to the internal resistance of the battery are dissipated in the form of heat directly on the battery and its contacts. High internal resistance can lead to overheating of batteries in demanding devices - e.g. flash units. Next to capacity, it is one of the most important and important parameters determining the performance of a battery or accumulator, the existence of which not everyone is aware of. There are only a few proven chargers on the market that are able to correctly measure and provide the user with the resistance value - such chargers include everActive NC-3000 for Ni-MH batteries and everActive LC-2100 for lithium-ion batteries.

Self discharge

Self-discharge - this is a phenomenon that occurs in batteries as a result of chemical reactions taking place in them without a connection between the battery poles. Self-discharge reduces the shelf life of batteries and causes them to have a lower charging capacity than was assumed when the cell was used.
How fast and how rapidly the self-discharge process occurs depends on the type of battery and factors such as operating and storage temperature.
Typically, lithium batteries have a lower self-discharge capacity (approx. 2-3% of total capacity/month), while nickel-based batteries are more prone to self-discharge (nickel-cadmium Ni-Cd 15-20% of total capacity/month, and nickel-metal hydride Ni-MH 30% of total capacity/month). In the case of cells made with Ni-MH technology, the exception is new generation batteries - e.g. Eneloop, which are able to maintain useful capacity for many years.
As you can see, this process has a very large impact on the usability of the battery.
Assuming what we know, namely that self-discharge is a chemical reaction, we can ask the question, what exactly are the factors that affect the process?
Self-discharge is a chemical process that occurs in a closed loop and typically occurs faster at higher temperatures. Storing the battery at lower temperatures lowers the rate of self-discharge and helps to preserve the initial energy stored in the battery.
More detailed causes of the phenomenon have not yet been thoroughly understood.

separator

An electrical insulator that separates the electrodes inside an electrochemical cell.

Electrochemical System

The structure and chemical components of the cell, which determine its parameters.

vitality

It determines the durability of the battery - it is usually given in work cycles. In general, the service life depends to a large extent on the operating conditions of the battery. Copyright ? Baltrade