Battery charger glossary


Ambient temperature: The temperature of the surroundings with respect to a particular reference point. The ambient temperature for a charger is the air temperature in the vicinity of the charger.
Ammeter: An instrument used to measure current. The unit for the measurement of current is amperes.
Ampacity: Current carrying or current providing capability.
Ampere: SI unit for the amount of electrical charge traveling through a conductor per second.
Absorption mode: The charging state during recharge where a lead acid battery accepts the final 15-25% of its capacity. The voltage for a 12V lead acid battery is regulated at approximately 14.6V during absorption while the battery acceptance current continually decreases.
Battery: Two or more electrochemical cells electrically connected in a desired series/parallel arrangement to achieve a particular voltage/current capability.
Breakdown voltage: The voltage where the dielectric insulation fails or is severely degraded by excessive leakage current or arcing.
Brownout: A reduction of the AC voltage, either by the utility company to reduce power consumption or due to heavy loading on a power line that has a high source impedance.
Bulk mode: The charging state during recharge where a lead acid battery accepts the 75-85% of its capacity. The charging current for a 12V lead acid battery is regulated at its maximum current output while the battery voltage continually increases until the absorption stage is reached.
Burn-in: Operating a battery charger or power supply, usually at or near rated load to verify the unit was manufactured correctly.
Capacity: The total number of ampere-hours (or watt-hours) that can be delivered by a battery under specified conditions of discharge, such as current draw and temperature.
Cell: The fundamental electrochemical unit generating or storing electrical energy. For instance, a lead acid 12V battery is obtained by placing in series six cells of 2V each.
Charging: The process of converting the current supplied to a battery from an external source into chemical energy stored by the battery for later use.
Closed circuit voltage: The instantaneous voltage of a battery when a load is applied, i.e., current is being drawn from the battery.
Continuous load: A load expected to continue for an extended period of time. Commonly electrical equipment is rated for peak load and continuous or average load.
Converter: An electrical circuit that transforms a DC input into a desired DC output.
Cross regulation: The effect of load change on one output to the regulation of another output. This is particularly important in multi-output battery chargers.
Current limiting: A protection circuit that limits the maximum output current in order to protect the load being driven and the battery charger or power supply providing the power.
Cut-off voltage: The battery voltage where further discharge is terminated to prevent deep discharge and subsequent damage to the battery.
Cycle: The discharging and charging of a rechargeable battery. Many manufacturers provide the number of charge/discharge cycles that a rechargeable battery can undergo before a measurable decrease in specification performance.
Derating: A reduction in an operating point compared to specification to improve reliability.
Discharge: The internal conversion of the chemical energy stored in the battery into electrical energy for outside use.
Discharge rate: The rate of current draw expressed in amperes, to indicate the amount of energy being delivered by the battery.
Drift: The change in a specified parameter, after a given amount of initial warm-up time.
Dropout: The minimum input voltage that is insufficient to maintain full regulation of the outputs of a battery charger or power supply.
Electrolyte: The chemical providing the ion transport mechanism between the positive and negative electrodes of a cell.
Energy density: The ratio of the total energy available from a battery divided its physical volume (joules per cubic meter) or its weight (joules per kilogram.)
Efficiency: The ratio of total output power to input power expressed as a percentage.
EMI: Electro-magnetic interference, which is the generation of electrical noise during the operation of a battery charger, power supply or other electrical or electronic equipment.
Floating output: An output of a battery charger or power supply that is not connected or referenced to any other output, and usually denotes total galvanic isolation from other outputs. Non-floating outputs usually share a common return.
Float mode: The maintenance state following bulk and absorption where a lead acid battery is at full capacity. The voltage for a 12V lead acid battery is regulated at approximately 13.5V during float and remains there indefinitely for long term storage. Internal battery losses are replenished by the charger during float to maintain the battery at full capacity.
Ground: A large conducting body, such as the earth that is used as a common return for an electric circuit and as an arbitrary point of zero potential. Common safety practice is to connect to earth through a ground connection or connections of sufficiently low impedance and having adequate ampacity to prevent the creation of voltages which could result in hazards to equipment or persons.
Ground fault circuit interrupter: A protection circuit that disables the source of electricity to a system when the ground current exceeds some predetermined value. This is to prevent ground current from flowing in an abnormal condition or in an abnormal path to protect people or equipment.
Ground loop: A term commonly used to indicate a connection of two points sharing a common electrical ground and being connected to the ground at two or more points allowing current to flow in an undesired path.
Hipot: Abbreviation for high potential, and generally refers to the high voltages used to test dielectric withstand capability for regulatory agency electrical safety requirements.
Input line filter: An internally or externally mounted low-pass filter or harmonic traps located at the battery charger or power supply input or output to reduce conducted or radiated emissions.
Inrush current: The peak AC current that flows into a battery charger or power supply during the initial period AC power is applied. This peak is usually greater than the normal operating current.
Joule: SI unit for the measurement of energy. It is defined as the amount of power, measured in watts, multiplied by the amount of time, measured in seconds.
Leakage current: Current flowing from the AC mains to earth ground. The current can be a result of a fault condition or AC current that normally flows through the EMI filter capacitors which are connected between the AC lines and ground.
Local sensing: The feedback point for the regulation loop is taken at the output terminals of the battery charger or power supply.
Ohmmeter: An instrument for measuring resistance.
Open voltage circuit: The voltage of a battery with no charging and no load applied, i.e., with no charge or discharge current present.
Overcharge: Charging beyond the point where the full capacity of the battery occurred.
Overcurrent: Any current in excess of the rated current of equipment or the ampacity of a conductor. It may result from overload, short circuit or ground fault.
Overload: Load exceeding the specification for which the system was intended.
Overvoltage protection: A circuit which shuts down the battery charger in the event of an output overvoltage condition.
PARD: Acronym for periodic and random deviation, referring to the sum of all ripple and noise components on the output of a battery charger or power supply.
Plenum: Chamber or space forming a part of an air conditioning system.
Primary cell (or battery): A battery not designed to be recharged and is discarded at the end of its first complete discharge.
Rated capaciy: The number of ampere-hours a battery is capable of supplying under a given set of conditions such as temperature, load and minimum voltage.
Remote sense: Sense lines connected from the regulation loop of the battery charger or power supply to the load in order to provide the ability to sense the voltage at the load. This provides compensation for voltage drops in the output cables or any other in line circuitry.
Reverse polarity protection: A protective feature which prevents the charger from damage and current draw from the battery when the charger leads are connected in reverse (plus charger to minus battery, etc.).
Safety ground: A conductive path to earth that is designed to protect persons from electrical shock by shunting away any dangerous currents that might occur due to malfunction or accident.
Secondary battery: A galvanic battery which, after discharge, may be restored to the fully charged state by the passage of an electric current though the battery in the opposite direction to that of discharge.
Self discharge: The loss of stored energy in a battery, with no load applied as a result of internal chemical processes.
Series connection: The interconnection of batteries such that the positive terminal of the first is connected to the negative terminal of the second, etc. Series connections result in the resulting voltage measured at the first and last cells being the sum of voltage of the all cells. Series connections also result in all batteries experiencing the same charge and discharge current.
Shelf life: The duration of storage under specified conditions at the end of which a battery continues to meet a given specification.
Standby current: The input current drawn by a battery charger when connected to the battery and not supplying power.
State of charge: The amount of energy stored in a battery at a given time.
Thermal protection: A protection circuit which prevents equipment from damaged by temperatures that the equipment is not designed to operate in.
Transient recovery time: The time required for an output voltage to be within specified limits after a specified change in input or load.
Taper charge: A charging technique delivering a moderately high rate charging current when the battery is at a low state of charge and tapering the charging current to lower rates as the battery is charged.
Vent: A normally sealed mechanism allowing for the controlled and intentional release of gases.
Volt: SI unit for the measurement of voltage, defined as joules (energy) per unit of electrical charge (coulombs). Voltage in laymen terms is commonly referred to as the amount of electrical pressure available to produce a current flow through a given resistance.
Voltage drop: The loss of voltage between two points due to the internal impedance or resistance of the interconnections.
Voltmeter: An instrument used to measure voltage. The unit for the measurement of voltage is volts.
Waterproof: Designed such that water and moisture will not enter the enclosure under specified test conditions.
Watt: SI unit for the measurement of power. For DC, the amount of power is obtained by multiplying volts times amperes.




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