Definitions

Ambient temperature:
The average temperature of the battery's surrounding medium, typically air.

Ampere-hours (Ah):
A measure of energy that is provided to or drawn from a battery. (A current of one ampere for one hour equals 1Ah).

Battery cycle:
A full charge followed by a full discharge (or the other way around).

Button cell:
A miniaturized battery. Most rechargeable button cells are NiCd or NiMH.

C-code:
Abbreviation of 'configuration code.' This information is typically stored in a battery adapter and configures the analyzer to the correct battery settings when installed.

C-rate:
Unit by which charge and discharge times are scaled. A battery rated at 1000mAh provides 1000mA for one hour if discharged at 1C. A discharge of 1C draws a current equal to the rated capacity. The same battery discharged at 0.5C would provide 500mA for two hours.

Capacity:
The electrical energy content of a battery as expressed in ampere-hours. The energy is measured by observing the time to discharge a battery at a constant current until a specified cut-off voltage is reached.

Capacity offset:
A correction factor applied to the rating of a battery if discharged under different C?rates from the one rated.

Cell mismatch:
Cells within a battery pack containing different capacity and voltage levels.

Cell reversal:
The stronger cells of a battery (several cells connected in series) impose a voltage of reverse polarity across a weaker cell during a deep discharge.

Charge:
The process of replenishing or replacing the electrical charge in a rechargeable cell or battery.

Co-generation:
The utilization of heat produced as byproduct in converting oxygen and hydrogen to electricity in a fuel cell. The heat is used to drive steam turbines.

Coulomb:
A unit of electric charge used to measure the ingoing and outgoing discharge current of a battery. One coulomb (1C) is equal to the electricity transferred by a current of one ampere in one second. (The maximum energy a molecular weight of a chemical system can deliver is one faraday of energy or 96495.7C which is the equivalent of 26.8Ah of capacity.)

Coke:
Coal from which most of the gases have been removed by heating. Coke is used as an industrial fuel.

Current-limiting chargers:
A charger that keeps the charge current constant during the charge process but allows the voltage to fluctuate (typically used on NiCd and NiMH chargers).

Cycle:
A process consisting of a single charge and discharge of a rechargeable battery.

Cycle life:
The number of cycles a battery provides before it is no longer usable. (A battery is considered non-usable if its nominal capacity falls below 60 to 80 percent).

Cylindrical cell:
The positive and negative plates are rolled up and placed into a cylindrical container.

Double layer capacitor:
Capacitor with high farad rating. The high capacity is made possible by a double layer formed near the carbon electrode surface.

Dumb battery:
A battery which contains no electronic circuitry with which to communicate digitally.

Electrochemical Impedance Spectroscopy (EIS):
Used to investigate electrochemical characteristics of batteries. The method applies an AC potential at varying frequencies to an electrochemical cell and the current response is measured.

Electrode:
Conducting element within a cell in which an electrochemical reaction occurs. Normally includes active materials plus conductive and supportive elements.

Electrolyte:
A non-metallic conductor of electricity (typically liquid) between the positive and negative electrodes of a battery. The current is carried by the physical movement of ions.

Energy:
Voltage multiplied by current expressed in watts.

Energy density:
The amount of energy a cell can contain. Gravimetric energy is the watt-hours a battery is capable of providing per given weight (pound or kilogram), and volumetric energy is the watt-hours per given size (cubic inch or cubic centimeter). The energy is defined as nominal battery voltage multiplied by rated capacity.

Equalizing Charge:
With time, the charge levels of individual cells of a large battery tend to become slightly unbalanced. The equalizing charge applies an elevated charge voltage for a few hours to balance the cells. Used mainly for large lead acid cells.

Exercise:
Commonly understood as one or several discharge cycles to 1V/cell with subsequent recharge. Used to maintain NiCd & NiMH batteries.

Fast charge:
Typical fast charge time for a nickel-based battery is 1 hour; lithium-based is 3 hours. The fast-charger detects the state-of-charge and switches to trickle charge when full-charge is reached.

Float charge:
Similar to trickle charge. Compensates for the self-discharge on a lead acid battery.

Fuel cell:
An electrochemical device that generates electricity by converting oxygen and hydrogen into water.

Fuzzy logic:
A mathematical technique used to obtain an approximate output reading derived from various analog inputs. Fuzzy logic can be utilized to quick-test batteries.

Graphite:
A form of carbon.

Hydrogen battery:
A rechargeable battery commonly used for space applications.

Internal resistance:
Resistance to electrical current inside a cell or battery pack.

Impedance:
Resistance to electrical current created by reactance and ohmic resistance

Intelligent battery:
Also known as a 'smart' battery. The battery pack contains internal circuitry to enable communication between the battery and the user.

Intrinsically Safe:
A battery with built-in protection circuitry. These batteries are used primarily in explosive environments.

Ion:
A charged particle that is combined with a particle of opposite charge to produce a chemical salt.

Lead acid battery:
Rechargeable battery commonly used for wheeled and stationary applications. The plates consist of lead-antimony alloy.

Lithium battery:
A battery using lithium metal as negative electrode. Most lithium batteries are non-rechargeable.

Lithium ion battery:
A battery dependent on the flow of lithium ions. The lithium metal on the negative electrode is replaced with carbon to improve safety.

Lithium ion polymer:
A rechargeable battery similar to the Li?ion but with a solid polymer as electrolyte. Some gelled conductive material is added to promote conductivity.

Lithium polymer:
A rechargeable battery using solid polymer as electrolyte. Most lithium polymer batteries require heat to promote conductivity.

Load current:
The discharge current delivered to a battery-powered device.

Matrix:
The set of battery parameters stored in the battery adapter to enable the Cadex Quicktestä function.

Manganese:
A metallic chemical element.

Maintenance Requirements:
Battery maintenance prolongs battery life. Nickel-based batteries need a periodic full discharge to eliminate 'memory'. Lead acid batteries require periodic equalizing charge. Lithium-based batteries need little maintenance.

Memory:
Reversible capacity loss in NiCd and NiMH batteries. The modern definition of memory commonly refers to a change in crystalline formation from the desirable small size to a large size. Memory is often used to describe any reversible capacity loss on nickel-based batteries.

Milliampere-hour:
A battery capacity or rating. A battery that provides a current of 1000mA for 1 hour is rated at 1000mAh (or 1Ah).

Negative delta V (NDV):
A drop in battery voltage, which occurs when a sealed NiCd or NiMH battery reaches the full charge state and goes into overcharge.

Nickel cadmium battery:
A rechargeable battery using cadmium as the negative electrode.

Nominal voltage:
The cell voltage that is accepted as an industrial standard. (Cell voltages of 1.20 and 1.25V are used for NiCd and NiMH batteries).

Ohmic resistance:
Electrical resistance void of reactance.

Ohmtest™:
A measurement that reflects the internal resistance of a battery.

Organic:
Carbon-based solvent.

Overcharge:
Charging a battery after it reaches full charge. On overcharge, the battery can no longer absorb charge and the battery heats up.

Passivation layer:
A resistive layer that forms in some cells after prolonged storage. This layer must be broken to enable proper operation. Applying charge/discharge cycles often help in preparing the battery for use.

Polymer:
An ionic conductor that is an electrical insulator put passes ions.

Pouch cell:
A battery in which the typical metallic cylinder and glass-to-metal electrical feed-through is replaced with a flexible, heat-sealable foil package.

Primary battery:
A non-rechargeable battery. The active materials of a primary battery undergo an irreversible change during discharge.

Prismatic cell:
The positive and negative plates are stacked rather than rolled.

Protection circuit:
Circuitry built into the battery pack to maintain the safety of the battery and equipment in case of improper handling.

Quick charger:
A charger that charges a battery in 3 to 6 hours.

Quicktest™:
A method to quick test the state-of-health of a battery.

Rapid charge:
Same terminology as quick charger.

Reactance:
The presence of inductive and capacitive resistance.

Recondition:
A deep discharge below 1.0V/cell with a controlled current, causing a change to the molecular structure of the cell and a rebuilding of its chemical composition. Recondition helps break down large crystals to a more desirable small size, often restoring the battery to its full capacity. Applies to nickel-based batteries.

Resistance:
Opposition to electrical current flow. Batteries with high internal resistance are not able to deliver heavy current pulses or elevated loads.

Residual capacity:
The charge capacity remaining in a battery prior to charge.

Reverse load charge:
A charge method that intersperses discharge pulses between charge pulses to promote the recombination of gases generated during fast charge. Reverse load charge also helps to reduce memory.

Secondary battery:
A battery that is rechargeable by reversing its chemical reaction.

Self-discharge:
Capacity loss during storage due to the internal leakage between the positive and negative cell plates.

Single wire bus:
Simplified 'smart' battery using only one wire for digital communications to the outside world.

Slow charge:
Typically an over-night charge lasting 10 to 16 hours at a charge current of 0.1C. A battery does not require instant removal when fully charged.

'Smart' battery:
Also known as an 'intelligent battery.' A battery pack containing internal circuitry that enables communication between the battery and the user.

Soft cell:
A cell whose voltage rises above its defined boundaries during charging. This voltage rise may be caused by high cell impedance, cold battery temperature or lack of electrolyte.

Spectroscopy:
Same terminology as Electrochemical Impedance Spectroscopy.

Spinel:
A family of compounds that have a specific chemical structure. In lithium-ion batteries, the structure is manganese-based.

State-of-Charge (SoC):
A measurement that reflects the state-of-charge of a battery. The SoC alone is not a valid indicator of the battery's runtime. The SoC readings will indicate 100 percent, even if a battery whose acceptance has dropped to 50 percent is fully charged.

State-of-Health (SoH):
A measurement that reflects the state-of-health of a battery, taking into account charge acceptance, internal resistance, voltage and self-discharge.

Sulfation:
The growth of lead sulfate crystals in lead acid batteries, which inhibits current flow. Sulfation is caused by storage at low state-of-charge.

Supercapacitor:
A capacitor that can store a high amount of energy. Supercapacitors hold about one tenth the energy of a nickel or lithium-based battery.

System Management Bus (SMBus):
A commonly used protocol for the 'smart' battery.

Thermal battery voltage:
Batteries are non-linear systems. The equations, which govern the battery's response, becomes linear below 25mV/cell at 25°C. This voltage is called the battery thermal voltage.

Thermal runaway:
A condition whereby an electrochemical cell will overheat and destroy itself through internal heat generation. This may be caused by overcharge or high current discharge and other abusive conditions.

Trickle charge:
Maintenance charge to compensate for the battery's self-discharge.

Topping Charge:
To complete the fast charge, a topping charge is applied that continues charging the battery for 30 minutes or longer at a lower current. Typically used for nickel-based batteries.

Voltage delay:
During open circuit storage, some battery systems develop a passivation film on the surface of the active material. On the initial discharge, these batteries demonstrate a momentarily lower than normal voltage until this film is removed by the discharge.

Voltage limit:
The voltage value beyond which a battery is not permitted to rise on charge or fall on discharge.

Voltage-limiting charger:
A charger that limits the maximum voltage to a battery but allows the current to drop towards the end of charge. A voltage-limiting charge may also include current-limiting. (Typically used on lead acid and Li?ion battery chargers).

Zapping:
The process of applying a momentary high current pulse to a battery to improve performance. Zapping is said to improve new NiCd batteries but does not restore weak packs.
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Created: March 2003, Last edited: March 2005