Electrical Fundamentals and Battery Technology

Vocabulary flashcards covering key electrical concepts and battery technology from the lecture notes.

Hydrometer

An instrument used to measure the specific gravity of the electrolyte in a lead-acid battery.

Temperature range for SG correction

70°F to 90°F; readings within this range do not require temperature correction.

Specific gravity (SG)

A measure of electrolyte density used to assess state of charge in lead-acid batteries.

Open-circuit voltage

Voltage of a lead-acid cell when no current is drawn; about 2.1 volts per cell.

Closed-circuit voltage

Voltage under load; lower than open-circuit due to internal resistance.

Electrolyte level indicator

Level should be up to the indicated mark inside the cell.

Gases released during charging

Hydrogen and oxygen.

Corrosion protection for battery compartments

Paint with asphaltic tar-based paint or polyurethane enamel.

Neutralizing spilled electrolyte

A solution of bicarbonate of soda and water.

Electrolyte in a lead-acid battery

A mixture of sulfuric acid and water.

Shop safety separation for batteries

Acid and nickel-cadmium batteries must be kept separate; tools used on one type should not be used on the other.

Title block information

Drawing title, drawing number, revision, scale, and other identifying data.

Inductor

A device that stores energy in a magnetic field; commonly a coil.

Impedance

Total opposition to alternating current; vector sum of resistance, capacitive reactance, and inductive reactance.

Coil (in context of inductors)

A wound conductor that functions as an inductor in many devices.

Polarity determination (electromagnet)

Use the left-hand rule; thumb points to the north pole.

Voltage

Electrical pressure driving current.

Volt

Unit of electrical potential difference.

Ammeter

Instrument used to measure electrical current.

Ampere

Basic unit of current; 1 ampere equals 1 coulomb per second.

Milliamp

One thousandth of an ampere.

Continuity

A complete circuit where electrons can flow from the power source to the load.

Ohmmeter

Instrument used to measure resistance and continuity (power off when measuring resistance).

Resistance

Opposition to the flow of electrons.

Ohm

Basic unit of electrical resistance.

Megohm

One million ohms.

Factors affecting resistance

Material, cross-sectional area, length, and temperature.

Resistor color code

Resistance value indicated by color bands on a resistor.

Capacitor

Two conductors separated by an insulator; stores energy in an electrostatic field.

Capacitance unit

Farad; basic unit of capacitance.

Capacitor in AC circuits

Capacitors cause the current to lead the voltage.

Electrolytic capacitor caution

Electrolytics are polarized and should not be used in AC circuits; they pass current in one direction.

DC circuit components

A source of energy, a load, and conductors to join them.

DC circuit types (component placement)

Series, parallel, and series-parallel configurations.

Ohm's law

Voltage equals current times resistance (V = I × R).

Power in DC circuits

Power equals voltage times current (P = V × I).

Horsepower to watts

1 horsepower = 746 watts.

True power (AC circuits)

Power in phase with the voltage; measured in watts.

Apparent power

Product of voltage and current; measured in volt-amperes (VA).

Reactive power

Power in inductive and capacitive reactances; measured in volt-amps reactive (VAR).

Power factor

Ratio of true power to apparent power; also resistance to impedance ratio.

Inductance

Ability to store energy in a magnetic field.

Henry

Unit of inductance.