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Thread: The Elmoto Dictionary

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    Seņor Member podolefsky's Avatar
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    The Elmoto Dictionary

    I wanted to start a thread on EV terminology. You can find most of this stuff scattered on the web, books, etc. I figured it would be useful to have it in one place, for elmoto folks. Don't know what some word or acronym means? Look it up in the dictionary.

    This will never be complete, so go ahead and post more, suggest changes and / or corrections. I’ll update the first two posts with them.

    (Numbers in () are footnotes, see post #4.)

    For a list of just acronyms, see post #5.

    Big thanks to Ted Dillard for contributing a boat load of definitions and acronyms, which came from his book.

    Thanks also to Captain Klapton for contributing a bunch.
    __________________________________________________ _____________________________


    Accumulator – An apparatus by means of which energy can be stored, such as a rechargeable battery. Such devices may be electrical, fluidic or mechanical. (see also Secondary battery).

    AC Induction Motor (ACIM, or Induction Motor) – A motor that uses induction to create a magnetic field in the rotor coils, in which commutation is done externally by the controller; takes 3-phase alternating current; uses Faraday's Law of electromagnetic induction to create a magnetic field in the rotor, (as opposed to BLDC and PMAC where permanent magnets provide the field).

    Actual Capacity or Available Capacity – The total battery capacity, usually expressed in ampere-hours or milliampere-hours, available to perform work. The actual capacity of a particular battery is determined by a number of factors, including the cut-off voltage, discharge rate, temperature, method of charge and the age and life history of the battery.

    Actuator - A device that creates mechanical motion by converting various forms of energy to rotating or linear mechanical energy.

    AEVA - The Australian Electric Vehicle Association

    Air Resistance - The drag force on an object moving through air. See drag.

    Alternate Fuel Vehicle A vehicle powered by fuel other than gasoline or diesel. Examples of alternative fuels are electricity, hydrogen, and compressed natural gas.

    Alternating Current (AC) – Electrical current in which the flow of electric charge periodically reverses direction. The standard type of electricity in homes and is commonly used to power an EV.

    Ambient Temperature (AMB) – The temperature of the space (air) around the motor. Most motors are designed to operate in an ambient not to exceed 40C (104F).

    American Wire Gauge (AWG) - A numeric system for describing the diameters of conducting wire. Larger numbers correspond to thinner wire. Wires larger than 1 AWG are 0, 00, etc. Zeros in large wire gauges are referred to at "aught", e.g. 0 AWG wire is 1/0, or "1 aught". Table of wire sizes.

    Amp or Ampere – A unit of measurement for an electrical current. One amp is the amount of current produced by an electromotive force of one volt acting through the resistance of one ohm. Named for the French physicist Andre Marie Ampere. The uni abbreviation for Amp is A but its mathematical symbol is “I”. Small currents are measured in milli-Amps (mA) or thousandths of an Amp.

    Ampacity (or ampere capacity) - The maximum amount of electrical current a conductor or device can carry before exceeding its temperature rating. (9)

    Amp hour or amphere hours (Ah) – A unit of elecrical charge, often used in battery specifications. Current in amps multiplied by time in hours equals ampere-hours. One amp hour is equal to a current of one ampere flowing for one hour. Also, 1 amp hour is equal to 1,000 mAh.

    Ampere-Hour Capacity – The number of ampere-hours which can be delivered by a battery on a single discharge. In an ideal battery, if you discharge a 100 Ah battery at 100 amps, the battery will drain completely in one hour. However, in a real battery you will get less – see note (1) below.

    Apparent Power – The magnitude of complex power in an AC circuit measured in VA.

    Anode – The side of the battery that conventional current flows into. During discharge, the negative electrode of the cell is the anode. During charge, that reverses and the positive electrode of the cell is the anode. The anode gives up electrons to the load circuit and dissolves into the electrolyte. (2)

    Aqueous Batteries – Batteries with water-based electrolytes. The electrolyte may not appear to be liquid since it can be absorbed by the battery’s separator.

    Arc - Electrical breakdown of a gas that produces an ongoing plasma discharge, resulting from a current through normally nonconductive media such as air.

    Armature – The power producing part of a motor. The armature is always current carrying; it can be either the rotor or the stator. (3)

    Axial Flux - A motor arrangement where the rotor intersects magnetic field lines which are concentrated axial to the motor shaft. See also Radial flux.


    Balancing - a process of bring all cells in a battery to an equal state of charge.

    Base Speed - Simply put, speed at the "knee" of a torque vs RPM graph. It's the speed at which you leave the constant torque regime. For a given motor, it is determined by the input voltage and the controller's current limit.

    Battery – An electrochemical device used to store energy. The term is usually applied to a group of two or more electric cells connected together electrically. In common usage, the term “battery” is also applied to a single cell, such as a AA battery. (4)

    Battery Capacity – The electric output of a cell or battery on a service test delivered before the cell reaches a specified final electrical condition and may be expressed in ampere-hours, watt- hours, or similar units.

    Battery Charger – A device capable of supplying electrical energy to a battery.

    Battery-Charge Rate – The current expressed in amperes (A) or milli amps (mA) at which a battery is charged. Maybe also be expressed as a C-rate.

    Back-electromotive Force (BEMF, also Counter-electromotive Force) – In simple terms, a voltage that opposes the applied voltage in a motor. BEMF increases with RPM. BEMF is a result of Lenz's Law of electomagnetism.

    Base Frequency (or Fundamental Frequency) - The highest amplitude, lowest frequency component of a signal comprised of multiple frequencies.

    Battery Electric Vehicle - See EV below, An electric vehicle whose electricity is exclusively stored in batteries rather than a fuel cell or generator.

    Battery Management System (BMS) - A device that monitors the battery system, generally at the pack and cell level. May use a mini computer or microprocessor. Can perform a number of functions from simple monitoring to balancing and control of other vehicle systems. Also may be built into charging system. Maybe be a human in the case that the human manually monitors and balances the battery.

    Blocked Rotor Test – A short duration test in which the rotor of an induction motor is held stationary while a voltage of 1/4 the rated frequency is applied. The voltage is chosen such that the full load current flows. This allows the measurement of the short circuit power factor, leakage reactance, and starting torque.

    Boost Converter – A type of DC converter which decreases the current but increases the voltage versus the input.

    Breakdown Torque - The maximum torque a motor will develop under increasing load conditions without an abrupt drop in speed and power. Sometimes called pull-out torque.

    Brush - Current conducting material in a DC motor, usually graphite, or a combination of graphite and other materials. The brush rides on the commutator of a motor and forms an electrical connection between the armature and the power source.

    Brushed Motor - a motor that uses brushes and a mechanical commutator. Maybe use direct current, but can use alternating current in the case of a universal motor.

    Brushless Direct Current Motor (BLDC) – a motor using a permanent magnet rotor, in which commutation is done externally by the controller. The DC in the name is misleading, since this motor actually takes 3-phase alternating current. Thus it is technically an AC motor. It is distinguished from PMAC in that the driving waveform is “trapezoidal”, as opposed to “sinusoidal”. More here.

    Buck Converter – A type of DC converter which increases the current but reduces the voltage versus the input.

    Bus Bar - A piece of metal that connects several electrical devices.


    CAN bus (Controller Area Network) - A vehicle bus standard designed to allow microcontrollers and devices to communicate with each other within a vehicle without a host computer. CAN is often used to let the battery management system, charger, and motor controller communicate with each other and other devices, such as displays.

    Canadian Standards Association (CSA) - The agency that sets safety standards for motors and other electric equipment used in Canada.

    Capacitance – The ability of a body to store electrical charge. Generally applied to a capacitor, can also describe properties of a cell or battery. Unit of capacitance is the Farad (F), but typical values are expressed in microfarads (μF or MFD).

    Capacitor - A passive, two-terminal device that stores electrical energy. Generally consists of two metallic plates sandwiching a dielectric material. See also Super Capacitor.

    Capacitor Start Motor - Or more specifically, Capacitor-Start, induction-run. Provides high starting and break-down torque, medium starting current. Used on hard starting applications such as compressors, positive displacement pumps, farm equipment, etc.

    Capacitor-Start, capacitor-run - Similar to capacitor-start, except have higher efficiency. Generally used in higher HP single phase ratings.

    Capacity – The capacity of a battery is a measure of the amount of either charge or energy that it can deliver in a single discharge. Battery capacity is normally listed as amp-hours (a measure of charge) or as Watt-hours (a measure of energy).

    Cathode – The side of the battery that conventional current flows out of. The cathode, in effect, oxidizes the anode or absorbs the electrons. During discharge, the positive electrode of a voltaic cell is the cathode. When charging, that reverses and the negative electrode of the cell is the cathode. (the positive side when discharging) (2)

    Cd – Drag coefficient, used to calculate the drag force on a moving object.

    CdA – Drag area, found by multiplying the drag coefficient (Cd) by the frontal area (A).

    Cell – An electrochemical device that stores chemical energy and can convert it into electrical energy. It is the basic “building block” of a battery.

    Centrifugal Start Switch - A mechanism that disconnects the starting circuit (start winding) when the rotor reaches approximately 75% of operating speed (usually in 2 or 3 seconds).

    Charge - Usually refers to electric charge, positive or negative. Can also refer to the amount of electrical charge stored in a cell. Or used as a verb, see Charging.

    Charge Rate – The amount of current applied to battery during the charging process. This rate is commonly expressed as a fraction of the capacity of the battery. For example, C/2 or C/5. E.g., applying 50A to a 100Ah battery is a charge rate of C/2.

    Charging – The process of converting electric energy, provided in the form of a current, into chemical energy within the cell or battery.

    Chemistry – A term usually referring to the cathode material of a cell. E.g., LiFePO4 refers to a cell with a lithium iron phosphate cathode.

    Complex Power – The power rating determined by multiplying the voltage and current in an AC circuit measured in VA.

    Contactor - An electrically controlled switch used for switching a power circuit, similar to a relay except with higher current ratings, and usually higher voltage ratings. Electric vehicle grade contactors can break 1000s of amps in an emergency situation, but are not made to break large currents repeatedly. Generally once they have been used in an emergency, they should be discarded and replaced.

    Controller (or Motor Controller) - A device or group of devices that serves to govern in some predetermined manner the performance of an electric motor. A motor controller might include a manual or automatic means for starting and stopping the motor, selecting forward or reverse rotation, selecting and regulating the speed, regulating or limiting the torque, and protecting against overloads and faults.

    Coulomb - A unit of electrical charge, equal to approximately 6.241 x 1018 electrons. Named after Charles-Augustin de Coulomb.

    Coulomb Counting - A method of determining State of Charge by integrating battery current over time. It counts the number of Coulombs, literally the number of electrons, that move into or out of a battery.

    Commutation – A means of changing the direction of magnetic fields in a motor in order to generate torque. In brushed motors, commutation done with a mechanical commutator. In a brushless motor, commutation is done externally to the motor by the motor controller.

    Commutator - In a brushed motor, the part of the armature that causes the electrical current to be switched to various armature windings. Properly sequenced switching creates the motor torque. It is the round thing with a bunch of slots in it that the brushes ride on, transmitting current from the power source to the armature.

    Constant-Current Charge – A charging process in which the current applied to the battery is maintained at a constant value.

    Constant-Voltage Charge – A charging process in which the voltage applied to a battery is held at a constant value.

    Continuous Duty - The operation of loads for extended time, generally over one hour.

    Conventional Current - The name given to current when it is considered to flow out of positive terminals and into negative terminals (or toward ground). Can be thought of as the flow of positive charge, opposite to the direction of electron flow. Physically, electrons are the charges that move through a circuit, so positive current is the flow of the absence of electrons.

    Copper Loss - The term given to heat produced by electrical circuits in the conductors, such as copper windings of a motor. The copper loss power is current squared times resistance (I2 R). The total copper energy loss is current squared times resistance times time (I2 R t). A motor's efficiency is lowered by the combination of copper losses and core losses.

    Core Loss - The term given to heat produced when a material in a motor is subjected to changing magnetic fields. Also called Iron Losses. For instance, losses due to changing magnetic fields creating eddy currents in the steel or iron parts of a motor. Can also be due to hysteresis in permanent magnets. A motor's efficiency is lowered by the combination of core losses and copper losses.

    Cutoff Voltage, final – The prescribed lower-limit voltage at which battery discharge is considered complete. The cutoff or final voltage is usually chosen so that the maximum useful capacity of the battery is realized. The cutoff voltage varies with the type of battery and the kind of service in which the battery is used. When testing the capacity of a NiMH or NiCD battery a cutoff voltage of 1.0 V is normally used. 0.9V is normally used as the cutoff voltage of an alkaline cell. A device that is designed with too high a cutoff voltage may stop operating while the battery still has significant capacity remaining. See also Low Voltage Cutoff.

    C-rate – A unit used to signify the charge or discharge rate of a battery, equal to the amp hour capacity divided by 1 hour. Thus 1C for a 100 Ah battery would be 100 A, C/5 for the same battery would be 20 A and C/10 would be 10 A. The current is C-rate X Ah, so a 100 Ah battery discharging at 10C puts out 1000 A.

    C-rating – A number given by a manufacturer specifying the discharge and / or charge current capabilities of a battery. Continuous C-rating is the current a cell is rated to produce for long periods (minutes or hours). Peak C-rating is the current a cell is rated to produce for a short time (usually less than 10 seconds). Peak may also be called burst, pulse, or max.

    Crr – Coefficient of rolling resistance.

    Current Crowding Effect (CCE) – The development of a nonuniform current density in a conductor placed in close proximity to other current carrying conductors.

    Current Density - Electrical current per unit cross sectional area of the conductor (A/m^2). Important for sizing conductors.

    Cycle – One sequence of charge and discharge.

    Cycle Life – For rechargeable batteries, the total number of charge/discharge cycles the cell can sustain before it’s capacity is significantly reduced. End of life is usually considered to be reached when the cell or battery delivers only 80% of rated ampere-hour capacity. Lead acid and NiMH batteries typically have a cycle life of 500 cycles, NiCd and Li-ion batteries can have a cycle life of over 1,000 cycles. The cycle of a battery is greatly influenced by a number of factors, including the depth of the cycle (deep or shallow), temperature, C-rate, and the method of recharging. Improper charge cycle cutoff can greatly reduce the cycle life of a battery.

    Cylindrical – a cell shaped like a cylinder, usually with a metal case.


    DC-DC Converter – A type of power supply which takes a DC input and outputs a DC current at a different voltage which can be higher or lower than the input voltage.

    Direct Current (DC) - A constant, non-varying current. The power supply available from batteries, DC generators (not alternators), or a rectified source used for special purpose applications. See also Alternating Current.

    Deep Cycle – A cycle in which the discharge is continued until the battery reaches its cut-off voltage, usually 80% of discharge.

    Depth of Discharge (DOD) - A measure of how much energy has been withdrawn from a battery. It is expressed as a percentage of the total battery capacity. For example – if you use 25ah of a 100ah battery, that is running the battery to 25% DOD.

    Discharge – The conversion of the chemical energy of the battery into electric energy.

    Discharge, deep – Withdrawal of all electrical energy to the end-point voltage before the cell or battery is recharged.

    Discharge, high-rate – Withdrawal of large currents for short intervals of time, usually at a rate that would completely discharge a cell or battery in less than one hour (less than 1C).

    Discharge, low-rate – Withdrawal of small currents for long periods of time, usually longer than one hour (greater than 1C).

    Drain – Withdrawal of current from a cell.

    Drag - Forces acting opposite to the relative motion of an object moving relative to a surrounding medium, usually a fluid or gas. Unlike dry friction, which is generally independent of velocity, drag forces depend on velocity.

    Dry Cell – A primary cell in which the electrolyte is absorbed in a porous medium, or is otherwise restrained from flowing. Common practice limits the term “dry cell” to the Leclanch‚ cell, which is the common commercial type.

    Duty Cycle - The relationship between operating time and the resting time of a device, such as an electric motor.


    Eddy Current - Circulating currents caused by magnetic induction in a conductive material.

    Efficiency - The ratio of the useful work performed to the energy expended in producing it. Can also be the ratio of power produced to power used. If a motor takes 100 kW and produces 90 kW, it is 90% efficient (the other 10% is wasted, usually as heat).

    Electrochemical Couple – The system of active materials within a cell that provides electrical energy storage through an electrochemical reaction.

    Electrode – An electrical conductor through which an electric current enters or leaves a conducting medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum. For electrolytic solutions, many solids, and molten masses, an electrode is an electrical conductor at the surface of which a change occurs from conduction by electrons to conduction by ions. For gases and vacuum, the electrodes merely serve to conduct electricity to and from the medium.

    Electrolyte – A chemical compound which, when fused or dissolved in certain solvents, will conduct an electric current. All electrolytes in the fused state or in solution give rise to ions which conduct the electric current. (5)

    Electronegativity - A chemical property that describes the tendency of an atom or molecule to attract electrons toward itself.

    Electropositivity – The opposite of electronegativiey; a measure of an element's ability to donate electrons. The degree to which an element in a galvanic cell will function as the positive element of the cell. An element with a large electropositivity will oxidize faster than an element with a smaller electropositivity.

    End Bell - Also called the "Endshield". The part of the motor that houses the bearing supporting the rotor and acts as a protective guard to the internal parts of the motor.

    End-of-Discharge Voltage – The voltage of the battery at termination of a discharge.

    End Ring – The ends of a squirrel cage rotor shorting the conducting bars together in parallel.

    Endshield - See End Bell.

    End Turn - The portions of a winding in a stator which are bent to form a loop and are therefor not active in torque production but still contribute to electrical resistance.

    Energy – The capacity to perform work. For a battery, expressed as capacity times voltage, given in Watt-hours.

    Energy Density – Energy per unit volume. Usually the maximum energy a cell can hold divided by its volume. Unit is W / L. Sometimes refers to energy per unit mass, but technically that is specific energy. See also Specific Energy.

    Excitation - The act of creating magnetic lines of force from a motor winding by applying voltage.
    Last edited by podolefsky; 02 February 2014 at 0947.

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    Field – The magnetic field component of a motor. Can be either the rotor or the stator and can be either an electromagnet or permanent magnet.

    Field Weakening - Reduction of the field strength above base speed. Can refer to techniques to actively reduce the field, such as shunting field current with a series motor, or timing advance with a permanent magnet motor. Can also refer simply to the reduced field strength due to BEMF increasing with RPM.

    Final Voltage (see Cutoff voltage)

    Float Charging – Method of recharging in which a secondary cell is continuously connected to a constant-voltage supply that maintains the cell in fully charged condition. Typically applied to lead acid batteries.

    Force - any influence that causes a free body to undergo acceleration.

    Frame - Standardized motor mounting and shaft dimensions as established by NEMA or IEC.

    Frequency - An expression of how often a complete cycle occurs. Cycles per second describe how many complete cycles occur in a given time increment. Hertz (Hz) has been adopted to describe cycles per second so that time as well as number of cycles is specified. The standard power supply in North America is 60hz. Most of the rest of the world has 50hz power.

    Fuel Cell Vehicle - A vehicle powered by a fuel cell, usually hydrogen. This is essentially an electric vehicle but using hydrogen to store energy rather than a battery.

    Full Load Amperes (FLA) - Line current (amperage) drawn by a motor when operating at rated load and voltage on motor nameplate. Important for proper wire size selection, and motor starter or drive selection. Also called full load current.

    Full-Load Torque - The force produced by a motor running at rated full-load speed at rated horsepower.

    Fundamental Frequency - See Base Frequency.

    Fuse - A piece of metal, connected in the circuit to be protected, that melts and interrupts the circuit when current exceeds a specified amount.


    Galvanic Cell – A combination of electrodes, separated by electrolyte, that is capable of producing electrical energy by electrochemical action.

    Gassing – The evolution of gas from one or both of the electrodes in a cell. Gassing commonly results from self-discharge or from the electrolysis of water in the electrolyte during charging.

    Generator - Any machine that converts mechanical energy into electrical energy.


    Harmonic - A frequency of some multiple of the base frequency.

    Hertz – Unit of frequency, in cycles per second, of a signal. Named after H.R. Hertz, the German scientist who discovered electrical oscillations.

    High Voltage Cutoff (HVC) – the voltage at which charging is stopped. Could be the highest rated voltage, or set lower to have a safety margin, or to improve cell longevity. Can be cell level or pack level.

    High Voltage Hairpin (HVH) - A stator winding construction comprised of pre-formed, square copper bars resembling hairpins, designed to reduce end turn resistance and increase slot fill, primarily used by Remy.

    High Voltage Test - Application of a voltage greater than the working voltage to test the adequacy of motor insulation. Often referred to as high potential test or “hi-pot”.

    Horsepower (HP) - A measure of the rate of work. 33,000 pounds lifted one foot in one minute, or 550 pounds lifted one foot in one second. 746 Watts of electrical power equals one horsepower.

    Hybrid Electric Vehicle (HEV) - A vehicle that combines conventional power production (e.g. an ICE) and an electric motor. This is usually just a more efficient way of using the standard fuel as there is no external source of electricity. See also Plug-in Hybrid Electric Vehicle.


    Ideal battery – A battery with zero internal resistance. Exists in theory only, but can be useful in modeling circuits.

    IEEE – Institute of Electrical and Electronics Engineers

    Impedance - The total opposition in an electric circuit to the flow of an alternating current. Expressed in Ohms. Related to, but not the same as resistance.

    Induction Motor - See AC Induction Motor.

    In-Runner – A very common motor construction where the rotor fits inside the stator.

    Insulation – A material that covers motor coils so that they do not connect electrically. In motors, classified by maximum allowable operating temperature. NEMA Classifications.

    Insulator – A material that conducts does not conduct current.

    Inverter - A type of power supply which changes a DC input into an AC output.

    Integral Horsepower Motor - A motor rated one horsepower or larger at 1800RPM. By NEMA definitions, this is any motor having a three digit frame, for example 143T.

    Intermittent Duty - The operation during alternate periods of load and rest. Usually expressed as 5 minutes, 30 minutes or 1 hour.

    Internal Combustion Engine – An engine in which a chemical fuel is combusted inside chambers, usually cylinders. The standard way to power a vehicle, this part is removed when converting to an electric car.

    Interior Permanent Magnet Motor (IMP) - A type of brushless motor in which the rotor consists of a stack of metal laminations with slots into which permanent magnets sit. Thus the magnets are on the interior, rather than on the surface of the rotor as in a surface permanent magnet motor. IPM motors generate both permanent magnet torque and reluctance torque due to the metal laminations.

    Internal Resistance (Ri or IR) – The resistance to the flow of an electric current within the cell or battery. Usually, this refers to the resistance of a battery that follows Ohm’s law (V = IR). It is based on a simple model of a battery. Internal resistance is related to, but not the same as, impedance.

    International Electrotechnical Commission (IEC) - The worldwide organization that promotes international unification of standards or norms. Its formal decisions on technical matters express, as nearly as possible, an international consensus.

    Intrinsic Safety - A protection technique for safe operation of electrical equipment in hazardous areas by limiting the energy available for ignition. Used mostly for small handheld devices. Virtually no electric vehicle could pass an intrinsic safety test, since it essentially limits devices to 100W or less. More here.


    Joule – Unit of energy. The work required to continuously produce one watt of power for one second; or one watt second (W-s) (compare kilo-Watt hour). This relationship can be used to define the Watt.

    Joule Heating (Ohmic heating, Resistive heating) - The heat produced due to an electrical current flowing through a resistive material. See also Copper Loss.

    Jumper - A metal connector. Often refers to connectors between cells in a battery.


    Kilo-Watt (kW) - A unit of power equal to 1000 watts and approximately equal to 1.34 horsepower.

    Kilo-Volt (kV) - One thousand volts.

    Kentucky Fried Fingers (KFF) - Burned fingers as a result of being in the path of an arc, such as when connecting high power battery terminals with bare hands. Believed to be originally coined by Methods on Endless Sphere.

    KE - Motor voltage constant. A unit relating applied voltage of a motor to RPM. Unit is V/RPM or V-s/rad. A motor with a voltage constant of 0.02 V/RPM will turn at 3600 RPM with 72V applied (with no load).

    KT - Motor torque constant. A unit relating torque of a motor to current. Unit is ft-lb/A or Nm/A. The torque a motor will produce when 1A is supplied. A motor with KT 0.1 ft-lb/A will produce 50 ft-lb with a current of 500A.

    KV - Motor velocity constant. A unit relating RPM of a motor to applied voltage. Unit is RPM/V or rad/V-s The RPM a motor will turn when 1V is applied with no load. A motor with KV of 50 RPM/V will turn at 3600 RPM with an applied voltage of 72V (with no load). Not to be confused with kilo-Volt (kV).


    Li - chemical symbol for lithium

    Lithium ion (Li-ion) - Any type of lithium-based battery.

    Lithium polymer (LiPo) – A lithium battery with a polymer (solid or gel) electrolyte (6)

    Litz Wire – A type of wire comprised of multiple, helically wound strands of thin wire which are electrically insulated from each other designed to reduce the skin effect and proximity effect for frequencies up to 1MHz.

    Load – The device connected to the output terminals of a circuit. Can be the work or power required of a device, such as of a motor to drive attached equipment. Expressed in Watts or amps for an electrical circuit. For a motor, expressed in horsepower or torque at a certain motor speed.

    Locked Rotor Current - Measured current with the rotor locked and with rated voltage and frequency applied to the motor.

    Locked Rotor Torque - Measured torque with the rotor locked and with rated voltage and frequency applied to the motor.

    Low Voltage Cutoff (LVC) – The voltage at which discharge is stopped. Could be the lowest rated voltage, or set higher to have a safety margin, or to improve cell longevity. Can be cell level of pack level.


    Magnetic Polarity - Distinguishes the location of North and South poles of a magnet. Magnetic lines of force emanate from the North pole of a magnet and terminate at the South pole.

    Mega-Watt (MW) - One million Watts.

    Memory Effect – A phenomenon in which a cell, operated in successive cycles to less than full depth of discharge, temporarily loses the remainder of its capacity at normal voltage levels (usually applies only to Ni-Cd cells). Note,
    memory effect can be induced in NiCd cells even if the level of discharge is not the same during each cycle. Memory effect is reversible. Lithium-ion cells do not have a memory effect.

    Motor - An electrical machine that converts electrical energy into mechanical energy.

    Motor Controller - See Controller.

    Mounting, Basic Types - The most common motor mounts include: rigid base, resilient base C face or D flange, and extended through bolts. NEMA Motor Dimensional Chart.

    Mush Coil - A coil made with round wire.


    Nano Crystalline Motor – Conducts energy approximately 10 times more efficiently than Iron core motors.

    National Electric Code (NEC) - A safety code regarding the use of electricity. The NEC is sponsored by the National Fire Protection Institute. It is also used by insurance inspectors and by many government bodies regulating building codes.

    NCOP14 - The Australian rulebook on modified electric vehicle compliance.

    Negative Sequence – A phase sequence resulting in a clockwise field rotation.

    Negative Terminal – The terminal of a battery from which electrons flow in the external circuit when the cell discharges. See Positive Terminal.

    Neighborhood Electric Vehicle - Used for short trips around ones community. Church, School, meeting, etc.

    NEMA (National Electrical Manufactures Association) - A non-profit trade organization, supported by manufacturers of electrical apparatus and supplies in the United States. Its standards alleviate misunderstandings and help buyers select the proper products. NEMA standards for motors cover frame sizes and dimensions, horsepower ratings, service factors, temperature rises and performance characteristics.

    Nominal voltage – The "named" voltage, so it is a rating. Can be the voltage of a fully charged cell when delivering rated current. Can also be the voltage or potential created by the chemical reaction in a cell. It is a rating independent of state-of-charge (e.g., LiFePO4 nominal voltage is usually 3.2V)

    Nonaqueous Batteries – Cells that do not contain water, such as those with molten salts or organic electrolytes.


    Ohm's Law - A physical law relating voltage, current, and resistance. Mathematically expressed as V = IR. Named for the German physicist Georg Ohm.

    Open Circuit – Condition of a battery which is neither on charge nor on discharge (i.e., disconnected from a circuit).

    Open-Circuit Voltage (OCV) – The difference in potential between the terminals of a cell when the circuit is open (i.e., a no-load condition).

    Optoisolator - A component that transfers electrical signals between two isolated components by using light. Usually an LED and a phototransistor in the same package. Often used to isolate two components, such as a high voltage vehicle battery from a low voltage (e.g. 12V) system.

    Out-Runner – A motor construction where the stator fits inside the circumference of the rotor. Most commonly used with brushless motors.

    Output Shaft - The shaft of a speed reducer assembly that is connected to the load. This may also be called the drive shaft or the slow speed shaft.

    Overhung load - Is the perpendicular force pushing against the side of an output shaft. This force is either from a weight hanging on the output shaft or from a sprocket, pulley or gear being used on the shaft.

    Oxidation – A chemical reaction that results in the release of electrons by an electrode’s active material.


    Pack Voltage – The voltage of the entire battery pack. (7)

    Parasitic Load - The power consumed when a device is shut off. See also Quiescent Current.

    Parallel Connection – The arrangement of cells in a battery made by connecting all positive terminals together and all negative terminals together. The voltage of the group remains the same as the voltage of the individual cell. The capacity is increased in proportion to the number of cells.

    Partial Zero Emissions Vehicle (PZEV) – A vehicle that meets SULEV tailpipe emission standards, have zero evaporative emissions and a 15 year / 150,000 mile warranty. No evaporative emissions means that they have fewer emissions while being driven than a typical gasoline car has while just idling.

    Permanent Magnet Alternating Current Motor (PMAC) - a motor using a permanent magnet rotor, in which commutation is done externally by the controller; takes 3-phase alternating current. It is distinguished from BLDC in that the driving waveform is “sinusoidal”, as opposed to “trapezoidal”. More here.

    Permanent Split Capacitor (PSC) - (Single Phase) Performance and applications similar to shaded pole motors, but more efficient, with lower line current and higher horsepower capabilities.

    Phase - One of the individual voltages applied to an AC system, such as a motor. A single-phase motor has one voltage in the shape of a sine wave applied to it. A three-phase motor has three individual voltages applied to it. The three phases are at 120 degrees with respect to each other so that peaks of voltage occur at even time intervals to balance the power received and delivered by the motor throughout its 360 degrees of rotation.

    Phase Change Material (PCM) - A material which changes phase with a relatively small temperature change, absorbing a large amount of energy in doing so. Used for thermal management in certain high-end battery packs such as the Tesla Model S.

    Phase Sequence – The relationship between two or more phases in an AC circuit referring to the order in which they occur in time.

    Plug-in Hybrid Electric Vehicle - A hybrid electric vehicle with a substantial battery pack which is able to be charged by an external source other than its fossil fuel (i.e. plugged into household electricity). These vehicles often have the ability to travel in a ‘pure electric mode’ without using any conventional fuels.

    Plugging - A method of braking a motor that involves applying partial or full voltage in reverse in order to bring the motor to zero speed.

    Polarity - As applied to electric devices, polarity indicates which terminal is positive and which is negative. As applied to magnets, it indicates which pole is North and which pole is South.

    Poles - Electromagnetic devices set up inside the motor by the placement and connection of the windings. The motor’s speed is 2 x 60 x f / n, where f is the supply frequency and n is the number of poles. For example, a 2 pole motor with 60 Hz will turn at 3600RPM.

    Positive Sequence – A phase sequence resulting in a counterclockwise field rotation.

    Positive Terminal – The terminal of a battery toward which electrons flow through the external circuit when the cell discharges. See Negative Terminal.

    Potentiometer - A variable resistor.

    Power – the rate at which work is performed or energy is converted. Unit is the Watt (W). In an electric circuit, power can be calculated as current times voltage (P = IV).

    Power Density – Power per unit volume. Usually the maximum power a cell can provide divided by its mass. Unit is W / kg. See also Specific Power.

    Power Factor - The ratio between real and reactive power in AC devices.

    Pouch – A cell made up of, well, a pouch. Usually metal foil, but not always.

    Primary Battery – A battery made up of primary cells. See Primary Cell.

    Primary Cell – A cell designed to produce electric current through an electrochemical reaction that is not efficiently reversible. The cell, when discharged, cannot be efficiently recharged by an electric current. Alakline, lithium, and zinc air are common types of primary cells.

    Prismatic – Just means rectangular. Commonly refers to large format LiFePO4 cells (e.g. CALB, GBS, Thundersky), but could be any cell that is rectangular in shape. (8)

    Proximity Effect – The tendency for current crowding(increased current density) to occur in the first conductors in a set of closely spaced coils or straight wires. Typically responsible for higher losses than the skin effect.

    Pull-Up Torque - The minimum torque delivered by a motor between zero and the rated RPM, equal to the maximum load a motor can accelerate to rated RPM.

    Pulse Width Modulation (PWM) – A method of modifying a signal by adjusting the width of voltage pulses. A high-efficiency technique for controlling voltage output in a motor controller. The voltage “seen” by the motor is proportional to the duty cycle. A 12V signal with a 50% duty cycle will be seen as 6V by the motor.
    Last edited by podolefsky; 02 February 2014 at 1240.
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    Quiescent Current - The current drawn by a device when there is no load. See also Parasitic Load.


    Radial Flux - A motor arrangement where the rotor intersects magnetic field lines which are concentrated radially to the motor shaft. See also Axial flux

    Rated Capacity – The number of ampere-hours a cell can deliver under specific conditions (rate of discharge, end voltage, temperature); usually the manufacturer’s rating.

    Reactive Power - The portion of power consumed in overcoming inductance and capacitance in AC circuits.

    Real Power - The portion of AC power involved in doing the intended work.

    Rechargeable – Capable of being recharged; refers to secondary cells or batteries.

    Recombination – State in which the gases normally formed within the battery cell during its operation, are recombined to form water.

    Reduction – A chemical process that results in the acceptance of electrons by an electrode’s active material.

    Regenerative Braking Systems – An EV with a braking system that uses the braking RPM load to charge the onboard batteries.

    Reactance (X) - The opposition of a circuit element to a change of electric current or voltage, due to that elements inductance or capacitance.

    Relay - An electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used (See, for example, solid state relay). Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal

    Reluctance - The characteristics of a magnetic field which resists the flow of magnetic lines of force through it.

    Reluctance Motor - A type of electric motor that induces non-permanent magnetic poles on the ferromagnetic rotor. There are several types of reluctance motor, including switched reluctance.

    Resistance - The property of a material that describes how much it opposes the flow of electric current.

    Resistor - A device that resists the flow of electrical current for the purpose of operation, protection or control. There are two types of resistors-fixed and variable. A fixed resistor has a fixed value of ohms while a variable resistor is adjustable. A variable resistor is also known as a potentiometer.

    Rest voltage – The voltage a cell with tend toward if it is not being charged or discharged. Can depend on the state of charge. Rest voltage will generally drop as SOC decreases.

    RMS – Root Mean Square value of a signal. Can be applied to voltage or current. For a sinusoidal signal, the RMS value is the peak value / √2 (approximately peak x 0.707). For a square wave, such as a PWM signal, the RMS value is the peak value / duty cycle.

    RPM – Revolutions Per Minute. The rotational frequency of an object. How fast a motor's rotor turns.

    RoHS – Restriction of Hazardous Substances.

    Rotation - The direction in which a shaft turns is either clockwise (CW) or counterclockwise (CCW). When specifying rotation, also state if viewed from the shaft end or the opposite shaft end of the motor.

    Rotor – The rotating part of a motor. Can be either the armature (brushed) or the field (brushless).


    SAE – Society of Automotive Engineers

    Seal – The structural part of a galvanic cell that restricts the escape of solvent or electrolyte from the cell and limits the ingress of air into the cell (the air may dry out the electrolyte or interfere with the chemical reactions).

    Secondary Battery – A battery made up of secondary cells. See Storage Battery; Storage Cell.

    Self Discharge – Discharge that takes place while the battery is in an open-circuit condition.

    Separator – The permeable membrane that allows the passage of ions, but prevents electrical contact between the anode and the cathode.

    Series Connection – The arrangement of cells in a battery configured by connecting the positive terminal of each successive cell to the negative terminal of the next adjacent cell so that their voltages are cumulative. See also Parallel Connection.

    Series Motor – A brushed motor in which the rotor and stator coils are connected in series, through a mechanical commutator. Current flows equally through all the coils, creating magnetic fields which interact to produce torque.

    Service Factor - A measure of the overload capacity built into a motor. A 1.15 SF means the motor can deliver 15% more than the rated horsepower without injurious overheating. A 1.10 SF motor should not be loaded beyond its rated horsepower. Service factors will vary for different horsepower motors and for different speeds.

    Shaded Pole Motor - (Single Phase) Motor has low starting torque, low cost. Usually used in direct-drive fans and small blowers, and in small gearmotors.

    Shallow Cycling – Charge and discharge cycles which do not allow the battery to approach its cutoff voltage. Shallow cycling of NiCd cells lead to “memory effect”. Shallow cycling is not detrimental to NiMH or Lithium-ion cells and it is the most beneficial for lead acid batteries.

    Shielding (or Shield) - Conductive or magnetic materials that block a space from electromagnetic fields. Wires are often shielded with a metallic wrap to protect from noise interference.

    Shelf Life – For a dry cell, the period of time (measured from date of manufacture), at a storage temperature of 21 degrees C (69 degrees F), after which the cell retains a specified percentage (usually 90%) of its original energy content.

    Short Ciruit (or Short) – A condition that occurs when a very low resistance electrical path is unintentionally created. Batteries can supply hundreds of amps if short-circuited, potentially melting the terminals and creating sparks.

    Short Discharge Time (SDT) - A theoretical method of calculating cell or pack efficiency independently of capacity and voltage. Credited to Elithion founder Davide Andrea. It is the theoretical time it would take for a cell to completely discharge if the terminals were shorted. It is based on the cell's nominal voltage and internal resistance. A lower SDT is considered to indicate a more efficient cell. The SDT does not reflect how a real cell would behave, since most cells, if shorted, would undergo massive heating, changing the properties of the cell and most likely causing permanent damage.

    Skew Angle – The angel by which the rotor poles or conductors differ from the stator poles. Zero degrees being parallel.

    Skin Effect – The tendency for higher frequencies of AC to cause the majority of current to flow at the surface of a conductor.

    Solid State Relay (SSR) - A relay that has no moving parts, and instead uses a semiconductor device to perform switching. Many SSRs use an optical device for isolated switching.

    Split Phase (or more specifically Split-Phase start-induction run) - (Single Phase) Motor has moderate starting torque, high breakdown torque. Used on easy-starting equipment, such as belt-driven fans and blowers, grinders, centrifugal pumps, gearmotors, ect.

    Specific Energy – Energy per unit mass. Usually the maximum energy a cell can hold divided by its mass. Unit is Wh / kg. See also Energy Density.

    Specific Power – Power per unit mass. Usually the maximum power a cell can provide divided by its mass. Unit is W / kg. See also Power Density.

    Squirrel Cage Rotor – A type of rotor commonly found in induction motors which is made from parallel cast aluminum or copper bars connected at the ends by end rings encased in thin iron lamination.

    Starting Torque – Torque produced by a motor as it begins to turn from standstill and accelerate (sometimes called locked rotor torque).

    Starting-Lighting-Ignition (SLI) Battery – A battery designed to start internal combustion engines and to power the electrical systems in automobiles when the engine is not running. SLI batteries can be used in emergency lighting situations.

    State of Charge (SOC) - The level of charge stored in a battery, equivalent to a fuel gauge. 100% SOC is a full battery, 0% SOC is empty. The inverse of Depth of Discharge. SOC is measured in a number of ways. Voltage can be a reasonable indicator of SOC for some cell types, such as lead-acid, but it generally not a good indicator of SOC for lithium-ion cells. A better, but not perfect, method is "Coulomb Counting". The best SOC methods use a combination of voltage, current, and other parameters such as temperature.

    Stationary Battery – A secondary battery designed for use in a fixed location.

    Stator – The stationary part of a motor. Can be either the armature (brushless) or the field (brushed).

    Storage Battery – An assembly of identical cells in which the electrochemical action is reversible so that the battery may be recharged by passing a current through the cells in the opposite direction to that of discharge. While many non-storage batteries have a reversible process, only those that are economically rechargeable are classified as storage batteries. Synonym: Accumulator; Secondary Battery. See Secondary Cell.

    Storage Cell – An electrolytic cell for the generation of electric energy in which the cell after being discharged may be restored to a charged condition by an electric current flowing in a direction opposite the flow of current when the cell discharges. Synonym: Secondary Cell. See Storage Battery.

    Surface Permanent Magnet Motor (SPM) - A type of brushless motor in which permanent magnets are attached to the surface of the rotor. See also Interior Permanent Magnet Motor.

    Switched Reluctance Motor (SRM) - A type of motor that runs by reluctance torque, using a switched 3-phase voltage. Commutation technique is similar to BLDC. However, the rotor uses steel laminations, which are not permanently magnetized, rather than permanent magnets as used in BLDC.

    Switching Mode Power Supply (SMPS) – A type of power supply which uses a switching regulator to convert from one voltage to another(AC or DC) by adjusting the duty cycle of the regulator.


    Taper Charge – A charge regime delivering moderately high-rate charging current when the battery is at a low state of charge and tapering the current to lower rates as the battery becomes more fully charged.

    Temperature Rise - The amount by which a device, operating under rated conditions, is hotter than its surrounding ambient temperature.

    Temperature Tests - These determine the temperature of certain parts of a motor, above the ambient temperature, while operating under specific environmental conditions.

    Terminals – The parts of a device to which the external electric circuit is connected.

    Thermal mass - A thermally conductive material in contact physical with an object which experiences heating. Analogous to a spring, it can be used to stabilize temperatures during transient heating.

    Thermal Protector - A device, sensitive to current and heat, which protects the motor against overheating due to overload or failure to start. Basic types include automatic rest, manual reset and resistance temperature detectors.

    Thermal Runaway – A condition whereby an increase in temperature of a cell leads to further increase in temperature, often leading to the cell destroying itself. It is a kind of uncontrolled positive feedback. Can be caused in many ways, including high overcharge, high rate of discharge or other abusive conditions.

    Thermistor – A type of resistor whose resistance varies significantly with temperature, moreso than normal resistors. Used for measurement of temperature, such as on motors and batteries.

    Thermocouple - A pair of dissimilar conductors joined to produce a thermoelectric effect and used to accurately determine temperature. Thermocouples are used in laboratory testing, including measuring the temperature of motors and batteries.

    Thermostat - A protector, which is temperature-sensing only, that is mounted on the stator winding. Two leads from the device must be connected to control circuit, which initiates corrective action. The customer must specify if the thermostats are to be normally closed or normally open.

    Timing - The angular relationship between the rotor and stator field vectors. With neutral timing, the rotor field vector is maintained 90 degrees with respect to the stator field vector. This produces maximum torque at zero RPM. However, as the motor spins, the magnetic fields are distorted. Timing advance can help compensate for this distortion, causing the field vectors to be at 90 degrees again, but only at one particular speed. Efficiency at other speeds will be reduced. A motor should be neutrally timed if it is to operate in both forward and reverse.

    Timing Advance - Changing the anglular relationship between the rotor and stator field vectors in order to improve performance at high RPMs. Done with a brushed motor by rotating the brush holder. With brushless, it is handled by the controller, changing when voltage is applied in relationship to the rotor position.

    Torque – The tendency of a force to turn an object about an axis. Torque is defined as the applied force multiplied by the lever arm distance. Usually expressed in foot-lb (ft-lb) or Newton-meters (Nm). Can also be expressed in inch-lb or inch-ounces.

    Torque Constant - See KT.

    Total Harmonic Distortion (THD) – The percentage of voltage magnitude in signal which is comprised of harmonics of the base frequency.

    Traction Battery (or Traction Pack) - Usually, a rechargeable battery used for propulsion of a battery electric vehicle.

    Traction Motor - An electric motor providing the primary torque of a machine, usually for conversion into linear motion (traction).

    Transformer – A device that converts an input AC voltage to a higher or lower AC voltage. Used to isolate line voltage from a circuit or to change voltage and current to lower or higher values. Constructed of primary and secondary windings around a common magnetic core.

    Trickle Charging – A method of recharging in which a secondary cell is either continuously or intermittently connected to a constant-current supply that maintains the cell in fully charged condition.


    Underwriters Laboratories (UL) - Independent United States testing organization that sets safety standards for motors and other electrical equipment.

    Universal Motor – a brushed motor very similar in design to a series motor. These motors can be driven by direct current (DC) or alternating current (AC, single phase). Commonly used in power tools such as electric drills.


    VAR – The unit of reactive power standing for volt amps reactive

    Variable Frequency Drive (VFD) – A type of motor controller capable of controlling its frequency output as well as its voltage and current.

    Velocity Constant - See KV.

    Voltage Constant - See KE.

    Vent – A normally sealed mechanism that allows for the controlled escape of gases from within a cell.

    Volt – The unit of measurement of electromotive force, or difference of potential, which will cause a current of one ampere to flow through a resistance of one ohm. Named for Italian physicist Alessandro Volta (1745-1827).

    Voltage, cutoff – Voltage at the end of useful discharge. (See Voltage, end-point and Low Voltage Cutoff.)

    Voltage, end-point – Cell voltage below which the connected equipment will not operate or below which operation is not recommended.

    Voltage, nominal – See Nominal Voltage.

    Voltage - A measure of electromotive force that, when applied to conductors, will produce current in the conductors.


    Watt (W) – Unit of power, equal to one Joule per second. One horsepower is equal to 746 watts. Named after engineer James Watt.

    Wet Cell – A cell, the electrolyte of which is in liquid form and free to flow and move.

    Windage Losses - The losses in a motor associated with the movement of air caused by the rotor.

    Winding – Noun: refers to the coils of wire in a motor. Verb: refers to the process of wrapping coils of copper wire around a core, usually of steel. In an AC induction motor, the primary winding is a stator consisting of wire coils inserted into slots within steel laminations. The secondary winding of an AC induction motor is usually not a winding at all, but rather a cast rotor assembly. In a permanent magnet DC motor, the winding is the rotating armature.

    Work – The amount of energy transferred by a force acting through a distance.


    X - The symbol used to represent electrical reactance.


    Yellow - The color of Thunder Sky (now Winston) batteries.

    Yttrium - An element with the symbol Y, added to some batteries (such as Thunder Sky LiFeYPO4). The advantage of Yttrium over other LiFePO4 cells is roughly equivalent to that produced by the cells being yellow.


    Z - The symbol used to represent electrical impedance. Reactance (X) and resistance (R) are components of impedance: Z = R + iX, where i = √-1

    Zener Diode - A diode which allows current to flow in the forward direction in the same manner as an ideal diode, but also permits it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage. A common application is providing a fixed voltage in a circuit. Lee Hart designed a simple battery regulator using zener diodes, meant as a low cost way to balance a battery pack.


    18650 - A cylindrical cell that is approximately 18 mm diamater x 65 mm long. One of many standard battery sizes.
    Last edited by podolefsky; 06 February 2014 at 1044.
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    Seņor Member podolefsky's Avatar
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    (1) If you discharge a 60Ah cell at 60A, it will not last 1 hour. The Ah rating is usually measured at a low current, such as C/2 or less. For example, a 60Ah cell might give you 30A for 2 hours. However, if you draw 60A, or 180A, it will give you less. This is because at higher current, some of the energy is lost as heat. A 60Ah cell that is discharged at 180A might only give you 50Ah. The lower the internal resistance, the less energy you lose as heat.

    (2) When a battery is charging, anode is positive and cathode is negative. What is consistent is that current flows into the anode and out of the cathode. Note that here we mean positive current, which is opposite the direction of electron flow.

    (3) The two parts of a motor defined “electrically” are the armature and the field. The two parts defined “mechanically” are the rotor and the stator.

    (4) You’ll also hear “module”. A module is a collection of cells, and a collection of modules makes up a battery. A module might be 4 cells that make 12V, with 4 of those to make 48V. Batteries aren’t always made up of modules – usually large, high voltage batteries. You might also hear “pack”. Loosely, a pack is another name for battery, but sometimes people mean module.

    (5) In this sense, the stuff in a battery isn’t that much different from Gatorade. They’re both based on compounds that break up into ions when dissolved – in water or something else. DO NOT DRINK BATTERY ELECTROLYTE (just saying)

    (6) Not to be confused with “RC Lipo”, which is a particular type of lithium-polymer battery.

    (7) Sometimes you’ll see something called a “72V battery”. If it is lithium, you won’t find 72 of anything associated with this battery (volts, Ah, cells…nada). It’s actually 24 3.3V lithium cells, for 76.8V “nominal”. I think “72V” is just a hold-over from lead acid, which are 12V, so 6 of them make 72V. Same for 48V (actually 51.2V) or 96V (actually 102.4V).

    (8) See, for example, A123 pouch cells, which are prismatic lithium-polymer LiFePO4.

    (9) If you look up ampacity charts, they're usually for household wiring, and the values are lower than what you can use in an EV. A good way to know what size wire you need is to look at the manufacturer's spec for the device, such as a motor controller, and see what they recommend.
    Last edited by podolefsky; 01 February 2014 at 1148.
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    Seņor Member podolefsky's Avatar
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    Unit Converstions

    1 Ah = 3600 Coulombs

    1 V = 1 Joule / Coulomb

    1 A = 1 Coulomb / second

    1 radian = 180 / Pi degrees (Pi = 3.14159265...)
    1 radian = 57.2957795 degrees

    1 radian = 1 / 2Pi revolutions (rev)
    1 radian = 0.15915494 revolutions

    1 radian/s = 60 / 2Pi RPM (Revolutions per Minute)
    1 radian/s = 9.5493 RPM

    1 Nm = 0.7376 ft-lb

    1 km = 0.6214 miles

    1 kph = 0.6214 mph
    Last edited by podolefsky; 02 February 2014 at 1023.
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    Seņor Member podolefsky's Avatar
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    Ampacity now added

    I will add any more words folks come up with, made up or not, as long as you can define it (and use it in a sentence - and no, it can't be "your mom's a switched reluctance motor").
    - Noah Podolefsky -
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    Empulse R #24 frodus's Avatar
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    My Social Networking

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    Hahaha. Boom!

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    Empulse R #24 frodus's Avatar
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    KFF - Kentucky Fried Fingers.

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    AEVA - The Australian Electric Vehicle Association

    NCOP14 - The Australian rulebook on modified electric vehicle compliance.

    Axial Flux - a motor arrangement where the rotor intersects magnetic field lines which are concentrated axial to the motor shaft. cf. Radial flux

    Radial Flux - a motor arrangement where the rotor intersects magnetic field lines which are concentrated radially to the motor shaft. cf. Axial flux

  12. #10
    Senior Member jonescg's Avatar
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    Might want to add that

    1 Ah = 3600 Coulombs.
    1 V = 1 Joule / Coulomb
    1 A = 1 Coulomb / second

    And for the motor nerds,

    Voltage constant, KE = Volt second / rad
    Torque constant, KT = N.m / amp

    And for those of us who just graduated year 10 trigonometry...

    1 radian = 57.2957795 degrees
    1 radian = 0.15915494 rev
    1 rad/s = 9.5493 rpm

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