Electrical Systems

"The effects of electricity can be seen, felt, heard, and smelled."

Flow of Electricity: Electricity is the flow of electrons from one atom to another.  Electrical energy results from an electron leaving the orbit of one atom and jumping into the orbit of another atom.  Electrons, a negative charge, are naturally attracted to protons, a positive charge.  When an excess of electrons is present, a lack of electrons in another place, and a path between the two a continuous flow of electricity occurs.  

Two types of power or energy sources exist in an automotive electrical system.  These are chemical reactions and magnetism or induction.  A chemical process occurs in a car's battery.  Batteries have positive and negative terminals.  This imbalance between the positive and negative charges causes the flow of electrons and creates a power source.  Induction happens when electricity is produced with a power source, such as a battery, to move a conductor through a magnetic field.

Terminology:

• Current: The movement or flow of electricity.
• Ampere: A unit called an amp which is a measure of electrical current.
• Direct Current (DC): Electrons flow in one direction only.
• Alternating Current (AC): Electrons change direction at a fixed rate.
• Voltage: A field of attraction occurs when a positive substance is separated from a negative substance.  The distance between the two determines the strength of electrical pressure.  Voltage is a measure of electrical pressure.
• Resistance: As a substance flows, it can meet with resistance.  Resistance is determined by measuring heat produced by the flow.  An ohm is the unit of measured resistance.
• Closed Circuit: A completed circuit with a continuous flow through a completed path between two points.
• Open Circuit: An incomplete circuit between two points.
• Ground Wire: This is used to ground the electrical circuit for the negative side and can be connected directly to the frame, engine or transmission.

Ohm's Law: According to Georg Ohm (1827) it takes 1 volt of electrical pressure to push 1 ampere of electrical current through 1 ohm of resistance.  For further information on Ohm's Law refer to the following video link  Ohms Law Explained - The basics circuit theory (youtube.com) 

Power and Watt's Law: Electrical power is measured in Watt's and is mathematically expressed as P = I X E.  This current is multiplied by voltage.  For further information on Watt's Law refer to the following video link  WATTS LAW EXPLAINED (youtube.com) 

Circuits: An automotive circuit will contain five basic parts.

• A power source, such as a battery
• A conductor, such as a copper wire
• A load, such as a light bulb, electric motor, or resistor
• A controller, such as a switch or a relay
• A circuit protection device, such as a fuse or circuit breaker

Three types of circuits are used: Series circuits, parallel circuits, and series-parallel circuits.  For further information on these types of circuits refer to the following video link  Types of Electrical Circuits (youtube.com) 

Three types of electrical problems exist: Opens, shorts, or unwanted or high-resistance problems.  An open circuit is a circuit that does not have a completed path to travel.  For example, this can occur if there is a disconnected wire, a broken wire, or a switch is in the off position.  If a circuit is off, it is in the open position because switches open and close circuits to control the flow of electrical current.

A shorted circuit will follow a parallel leg or an unwanted path in a circuit.  This can be due to damaged wire insulation, loose wires or connections, damaged connections, improper wiring, or poor installation of accessories.  It will cause a high current flow that can burn wires or components.   If wires show signs up burning or insulation melting, this is most likely due to a short in the circuit.

A resistance problem occurs when resistance levels are too high in a circuit, therefore, causing the current level to be too low.  This unwanted resistance in the circuit can create heat at the site of resistance.  In turn, this can cause damage to wires or connectors.  A common cause of resistance will be rust or corrosion at the wire connector.

Multimeter tools are used to troubleshoot electrical and electronic systems issues.  These tools measure voltage, current, and resistance.   One can be purchased at the following link https://www.harborfreight.com/electrical/electrician-s-tools/multimeters-testers/9-function-digital-multimeter-with-audible-continuity-59410.html.

Batteries produce electrical energy by creating a chemical reaction that produces electrons in a battery.  This is called an electrochemical reaction.  It is due to the attraction of negative electrons to positive protons.  Within a battery cell are two plates, a negative and a positive plate.  A chemical solution of electrolytes reacts with the plates by causing an increase in electrons on the negative plate and a decrease in electrons on the positive plate.  When a closed circuit is connected to the two plates it causes a chemical reaction that creates a current of electrons flowing from negative to positive.  Recharging the battery moves electrons back from the positive side to the negative side of the battery.

Automotive batteries typically have a lead-acid design.  They are a maintenance-free battery meaning they are sealed and do not have gas vents (as some batteries have).  The life of a battery is affected by temperature, corrosion, overcharging or undercharging, loose mounting, and excessive cycling of the battery.

Jump-starting a vehicle can boost a dead battery enough to start it.  Ideally, one would use a battery booster pack to jump-start the dead vehicle and it's even better to use a battery charger.  Jump-starting can cause damage to electronic components.

Electromagnetism is used to create current flow in an electrical system.

A charging system is used to recharge the battery in an automotive vehicle.

A lighting system provides power to exterior and interior lights.

Electronic controls are any of the systems that help the vehicle operate, but are outside of the electrical systems with the vehicle.  An example is a computerized engine control. 

Erjavec, Jack and Thompson, Rob.  Automotive Technology: A Systems Approach.  6th Edition, (2015). Pg. 1467-1557.