Part 3 – Dictionary

Concepts to know.

Glossary and various terms

Glossary and various terms in connection with batteries,
© Celltech AB 2016-01-01

Here are some of the vocabulary and the concepts that are often used in conjunction with batteries and battery charging as well as some explanations. Subject to errors due to human error.

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A lead charger or Li-ion charger that charges with three voltage steps (actually a current step and two voltage steps). The same charger can be used for both cyclical and stand-by operation. Charges the battery in a fast, yet gentle manner, can be left connected indefinitely for lead-acid batteries intended for standby operation.

Commercial description of alkaline primary batteries with alkaline (basic) electrolytes. Have higher capacity and better properties than for example, manganese batteries which have acid-based electrolyte.

French physicist who inspired the name for electrical quantity current, written as the inside of formulas. Abbreviated A or mA _ associated with small batteries.

Denotes capacity, “energy content” of a battery, printed as Ah. Most interesting in connection with rechargeable systems, shows (theoretically) how much power you can withdraw from a fully charged battery over a certain period of time. In conjunction with smaller batteries used most often mAh 1 Ah = 1000 mAh. Often Ah is used sloppily, which is also used as name for current in connection with, for example, small power packs / battery eliminators, chargers, etc, and this may indicate that the supplier does not which have full understanding of the concepts.

Another name for the negative electrode in an electrochemical system, not to be confused with anode voltage which is a positive voltage in most contexts. The concept PANC (Positive Anode Negative  Cathode) from school days does not apply in the context of batteries. As above, a supplier / manufacturer who is not fully versed in this relationship should perhaps be avoided.

The correct designation for two or more cells that are assembled through (mostly) series. Most people say battery even when there’s only one cell, for example, flashlight batteries, etc.

Collective term for a whole series of rechargeable batteries, ranging from starter batteries and large truck batteries, to small enclosed VRLA (valve regulated lead–acid) batteries. Electrodes of lead, the electrolyte consists of diluted sulphuric acid.

Battery Management System is the collective term for circuit solutions with so-called Smart batteries with a communication bus connected to external devices such as displays, the charging control, engine control, capacity display etc.. See also the SM bus.

Battery Management Unit, part of BSM, see above i.e. control, capacity display, etc. See also the SM bus.

Original type of primary battery with acid-based electrolyte, sometimes also called motor battery or transistor battery. Replaced more and more by alkaline batteries.

A communication bus which is often used between devices in more advanced battery and energy systems. CAN (Controller Area Network) began to be used in vehicles and later in industry, mainly for its resistance to interference and safety. Available in versions with different data rate, various international standards, CAN open, etc. Bosch that began using CAN in the 80s owns most of the patents.

The individual “building blocks” of a battery. Different chemistries in different cell types have different voltage which, by coupling together in series gives the battery’s total voltage.

Expressions used in connection with batteries , which refers to charged or discharged current in relation to the nominal capacity. Example with a 1,5Ah cell: 1C = 1,5A, C / 10 or 0,1C = 150 mA.

In connection with batteries, we mean a full charge followed by a full discharge. The chargeable batteries have a limited maximum number of cycles before they are considered used up. For NiCd it is typically up to about 1000 or more, for NiMH 500-1000 and for lead and lithium-ion around 300-500 cycles. Variations and special batteries with other data exists.

Constructions or devices which more or less constantly charge and consume energy, for example mobile telephones, electric wheelchairs, golf carts, two-way radios. Charging equipment must be optimized for this operating mode for the battery to get long life.

One way to detect, control and cancel the rapid charging of NiCd and NiMH batteries. Also written as Δv charging, the Δ symbol is used, eg., in mathematical contexts to point out the change in the quantity or variety that comes after the symbol. In our case, it is the change of voltage that is interesting. A minus sign in front shows the change is negative (decreasing). Δt/ΔT also occurs in battery charging, here it is the relationship between time and temperature which is meaningful, one stops charging when a certain temperature increase per unit time is reached.

A measure of for example, the charge state of the electrolyte in a lead acid battery. The density (here acid density) of a fully charged lead-acid battery is at 1,28 g / cm3, while a depleted is around 1,10. Measured with a hydrometer or density tester. Density (energy density) is also used as a term to show how “effective” a battery system is. One can distinguish between volumetric and gravimetric density, that is to say, the amount of energy per volume or weight of a battery or a cell.

A semiconductor component that only releases current in one direction. Located sometimes in batteries for eg., to prevent accidental charging or prevent discharge through charging contacts.

Depth Of Discharge. A concept in battery usage to show how much of the total capacity one uses in cyclic operation. Often one chooses DOD to, for example, 80%, to get the longest lifespan of the battery system.

DOnald Safe BAttery System, a system of internal protection function for batteries in blocks with serial and / or parallel connected cells that were introduced in 2007 for predominantly electric vehicle batteries.

Often used in electrical applications, see Watts.

The ion-carrying medium of a cell, acid-based (acid) or alkaline (basic) and may be in liquid, gel or solid form.

The material in the cell in which the chemical energy is converted to electrical, which is taken out via the positive and negative connection. The electrodes can be of different materials, metal or carbon for example

Electrode material (the positive pole) of porous nickel (Ni foam) instead of for example, sintered nickel. Both provide high surface area, which increases the capacity of the cell.

A process that occurs at the end of charging in lead-acid batteries, whereby oxygen and hydrogen are released and flow out of the battery. Hydrogen gas is highly flammable, and with the “right” mix of air / oxygen forms explosive oxy-hydrogen gas, therefore it is important with ventilation when opening lead acid batteries. When exhausted lead acid batteries are recycled the gases are “recombined” and form water. Also other cell types can form excess pressure and are therefore often provided with a safety valve. Most batteries and battery chemistries may release a small amount of oxygen and hydrogen.

High drain refers to the discharge current. A cell type that is specifically designed for applications with high currents, such as machine tools and RC cars. A standard cell has higher internal resistance, hence its voltage drops more under load, while a high-drain cell has very low internal resistance.

All power sources and batteries have an internal resistance measured in Ohm or mOhm, usually quite low, for example, 100 mOhm or less. It is internal resistance that determines the maximum current that may be taken out of a battery, for example when there’s a short circuit. Even in “normal” operation the resistance value is in effect and determines how much the voltage in the battery will drop when it is loaded. Internal resistance increases afterwards as the battery is depleted or discharged, therefore also decreasing the voltage, usually rather slowly at first, then faster. See also, recovery.

Similar to internal resistance, but refers to alternating current resistance. Has significance, among other things when the load is pulsing, for example, with GSM phones.

Another name for a positive electrode in an electrochemical system. See also Anode.

A cylindrical cell in which the height is less than the diameter.

A factor, usually 1,4 for, for example, NiCd or NiMH which one multiplies the time with to compensate for losses during charging for example, temperature losses. Example: When one charges a 1 Ah battery with 1A, theoretically it will be fully charged in 1 hour, but with the charge factor included, the time is 1,4 hours. One can see the charge factor as another name for efficiency, no battery or power source will reach 100%, there is always larger or smaller losses in the system. A common and simple way to state this is that heat is formed where you do not want it.

Collective term for a series of primary use batteries in which lithium in some form is included. High cell voltage, 3,0-3,6V and high energy density and long shelf life characterize all lithium technologies. Even lithium cells with 1,5V voltage are common today as a qualified alternative to alkaline cells of the consumer type with AAA, AA and 9V size.

A rechargeable system with high energy density. Nominal cell voltage 3,7V and performs for low to medium-high currents, is used more and more in mobile phones, two-way radios and other portable devices. Used also in connection with large-series / parallel-connected batteries in electric vehicles. Lithium-ion Manganese(IV) oxide has the same nominal voltage and can operate at higher currents.

A variant of the lithium system, where a different design of the electrodes (foils) can shape the cell in the desired way. Can be designed for both low and high currents.

Another variant with a lower nominal cell voltage 3,2V but which can be executed with much higher current capability and good of cycling ability.

Trademark from Bourns, see Polyswitch and PTC resistor.

A registered trademark of the SAFT corporation, but is commonly used also by others in the industry to describe Ni-Cd batteries.

Abbreviation for Nickel-Cadmium. The story goes back to 1899 when the Swede Waldemar Jungner invented the NiFe battery. The electrolyte is alkaline, and today’s cells are found in a variety of special versions for high temperatures, fast charging, etc. NiCd batteries have a very low internal resistance.

Are those plates which are spot welded between the cells to connect terminals for series or parallel connections in the manufacturing of a battery pack. Sometimes called the welding plate or solder plate (when referring to the soldering of the connection wires on these). Manufactured out of pure nickel for good weldability with the cells. Expressions like nickel straps and tabs are also used both in English and Swenglish.

Abbreviation for Nickel-metal hydride. A rechargeable cell where the dangerous heavy metal, cadmium, has been replaced by “metallic hydrogen”. As with NiCd, the electrolyte is alkaline.

See standard charge.

This is the battery or the cell’s stamped on capacity, specified in Ah (amp-hours). The available capacity is dependent on the load current, temperature, end voltage etc.

Temperature-dependent component that is often used in batteries in order to detect the cell temperature. NTC comes from the term Negative Temperature Coefficient. Also known as a thermistor or NTC thermistor, and comes in many different resistance values. The nominal value is normally specified at 20 ° C and when the temperature rises the resistance value reduces according to a specific curve (K value). 10Kohm is a common resistance value in the context of batteries .

Georg Simon Ohm was a German physicist who gave his name to the electrical quantity resistance. Written with the character Ω (Omega), represented by R in formulas.  It is widely used to describe all electronic devices and even sometimes in batteries that, among other things, restrict current. See also NTC and PTC.

Trademark of Raychem see PTC resistor. Often used in batteries as a short-circuit protection, there are many “current values” and applications.

PTC thermistors are temperature-dependent components which in special designs can function as a power fuse in eg., battery connection (Polyswitch, Multi-fuse). They reset themselves when they short circuit or when the load is removed. Available in values from the 1A up to around 10A.

A standard PTC thermistor works in the opposite way from an NTC thermistor (Positive Temperature Coefficient), ie., the resistance increases as the temperature increases.

Trademark of Raychem see PTC resistor. Often used in batteries as a short-circuit protection, there are many “current values” and applications.

A battery that is used once, and can nor should be recharged. The name comes from the days when one used large primary batteries for recharging for example, lead-acid batteries. See also secondary batteries.

Flat of rectangular cell that more effectively than cylindrical cells can be built into a housing. The price is slightly higher than for cylindrical cells, hence the price difference on thin “slim” versus “normal” batteries for portable devices.

See fast charging.

See gassing.

See Ohms.

System Management Bus, is a term for a type of communication bus (data bus) used between devices in systems with so-called smart batteries. A battery with a built-in electronic “power gauge” that shows the capacity content etc. I2C bus and CAN bus are alternatives with a similar communications protocol.

Used in the context of batteries for connecting multiple cells in a loop. The voltage of the battery is increased by a factor corresponding to each cell’s voltage, capacity in watt-hours as well, but not current capacity or ampere-hours. See also parallel connections.

Term for the insulating material in the cells that separates (keeps apart) the positive as well as negative electrode material.

Finely ground material is compressed under high pressure and heat. Forms a large active surface which provides high current capacity in the cells.

All batteries have a certain self-discharge, which can vary from as much as up to 10 percent during the first day for, for example, NiMH and down to less than 1 percent per month for some Lithium technologies. Storage conditions and temperature can affect self-discharge.

Sealed Lead Acid batteries. If the electrolyte is immobilized in a porous material it can be mounted in any position, as opposed to open batteries with liquid electrolyte.  A valve exists which is capable of opening in the event of overpressure in the battery. This is therefore also called valve-regulated battery (VRLA).

The thin plastic film that is closest to the bare metal cell. Can be self-adhesive or in the form of a shrink film.

The voltage at which a certain battery (chemical system) is considered discharged. Usually stated per cell. You have to multiply to get the battery voltage. Examples of different final voltages are 1,75V for lead, 1,0V for NiCd / NiMH and 0,9V for an alkaline dry battery (primary battery).

Most NiCd and NiMH cells today are designed to be able to charge in 1-1,5 hours, even shorter charging times occur. In the case of fast charging, you must always monitor and interrupt the charging at the right time to avoid overcharging, which destroys the cells. Some Lithium-ion technologies can allow charging times as short as 10-15 minutes to achieve at least 80 percent charge.

State of Charge. The term is often used in the context of batteries. It is particularly relevant after the change in the transport rules for air freight from April 2016, which states that there may be a maximum of 30% SoC in rechargeable lithium systems during transport. There are some exceptions to the rules, for example for batteries built into their application or when shipping by boat or on land, but it is believed that these will follow. In practice, virtually all batteries and cells are already shipped out of the manufacturer with 30% SoC, even for freight other than aviation.

This usually refers to the C / 10 rule, that is to say, you charge with one-tenth of the cell’s or the battery’s nominal capacity for approximately 14 hours.

Equipment with batteries that await on standby for possible power failure, e.g. UPS, fire and burglar alarms, etc. Constantly maintained by the connected charging equipment.

Collective term for protection component. Usually refers to overcurrent protection. The common value in small batteries is 1-10A.

Another name for ordinary alkaline or manganese dioxide battery (primary battery). Coming from a time when these went from being an open vessel with liquid electrolyte, which was difficult to handle and to a closed “dry cell”. The contents are nevertheless rather wet with the electrolyte absorbed in various porous substances or electrodes.

Collective term for different types of fuses that you mount inside some batteries in contact with the cells. The fuse is triggered if the temperature rises too high, to prevent damage to the battery and environment (disaster protection). A temperature fuse can not be reset and is usually not interchangeable. Ordinary temperature limits are 75-95⁰ C.

Component that is used in batteries when you want to ensure that the battery circuit breaks if the cells’ temperature goes above a certain limit. Can also be used to control (cancel) the charge. Common values are 45-70⁰ C. The switch resets itself automatically when the temperature drops again, or with an external pushbutton.

See thermal switch.

See maintenance charging.

Stands for Uninterruptable Power Supply, an appliance or a larger system that includes batteries and charging equipment with monitoring circuits, and usually a voltage converter to supply 230V power to the connected equipment, for example, a computer or emergency alarm system , etc. During a power outage the equipment continues to operate for a certain time. Available in power from a few hundred watts to several hundred kilowatts.

In order to maintain full charging and compensate for self-discharge, it is recommended to continue charging after fast or normal charging with a charging current that is carefully adapted to the cell type, usually C / 20-C / 80.

Refers to the type of positive terminal available on normal consumer cells. The production and construction of the battery pack often uses a different type of cell with smooth plus poles, which is better suited for spot welding of connections between cells. The finished battery also gets a smoother surface which is easier to encapsulate.

Lead-acid battery, see SLA

Comes from the Italian physicist Alessandro Volta (Voltaic pile was an early form of battery). Denotes the electrical quantity voltage, abbreviated V, but is written as U in formulas.

Valve Regulated Lead-Acid, Lead-acid battery, see SLA

James Watt from Scotland is a physicist to highlight. Denotes electrical (and also mechanical) magnitude power, abbreviated W, written as P in formulas. By multiplying current and voltage, you get the power in electrical contexts. See also Watt-hours.

The watt-hour (symbolized Wh) is a unit of energy equivalent to one watt (1 W) of power expended for one hour (1 h) of time.  A cell with 1,5V and 18Ah contains 27 Wh.
The advantage of using Wh is that this corresponds exactly to the number of cells inside the battery, unlike Ah, and it is easy to calculate the total capacity if you know the number. The weight of the battery also gives a good indication of the total capacity in Wh when you have found out the data or spec of the individual cell.

Most people know that a battery that is allowed to rest for a while is recovered and can provide a little more energy, for example in a flashlight.

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