Electrical engineer working on circuit board

Electrical

Sustainable Energy

Power and Energy

Units of power are HP or KW. 1 HP = 747 kW. Voltage x Current = Watts (V x I = W). Energy is power over time or kWh. We average one kilowatt of power in a one hour race for a total of 1 kWh.

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Electric Power

Voltage and Current

Electrical shock can be dangerous, so working with lower voltages is a big safety benefit. Electric vehicles can use 400 - 800 volt systems, most homebuilt cars are in the range of 200 volts, but lighter/smaller vehicles can get by with 24 - 48 volts. Electric bicycles use 36V, 48V, 60V and even 72V packs.

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Electric Current 

Voltmeter

Wires and Connectors 

Electronic Wires

Wire gauge (size) is sized according to the maximum amount of current that it will carry. There are sizing charts (here). Wire is heavy and expensive so the lightest gauge should be used for those reasons. Welding cable is commonly used for the drive system cabling. Wire quality varies with strand count (higher strand count is more flexible and more suitable for shock/vibration environments) and also wire insulation.

Connector pins and wire terminals can be crimped or soldered. Both are reliable methods if done properly, and the most important thing is strain relief (making sure the wire will not pull on the connection). Heat shrink is typically used on all terminations, and wire sheathing can be used to protect wire bundles (here). Here are some sources for various connectors and terminals. Some connectors require special crimping tools and pin extraction tools, but many use common standard crimping tools

 

Resources: 

Electrathon Handbook page 9

Electrical Connectors Information

Guide to Wire Gauge Sizes

Batteries and Charging

Electrathon cars usually use lead acid batteries. They are heavy but cheap and readily available, and do not require a Battery Management System (BMS) which keeps the designs simpler and also safer. Some lithium chemistries are very volatile and can be a fire risk if poor quality or if not used properly.

Resources: 

Electrathon Handbook page 8,12 and 15

Battery Technology and Power

Power w/ Calculations

Batteries
Hardware Tools

Mechanical

Race Flag

Physics (Forces, Energy, Losses, Friction, Aerodynamics)

Aerodynamics describes the effects of air flowing past your moving vehicle.

Friction is the energy lost as one surface pushes against another

Resources:

Electrathon Handbook p  12 and 16

A STUDY in FORCE

Friction

Finding MPG

Moment of Inertia w/ Calculations

Materials (Steel, Aluminum, Composites)

Most vehicles use steel tubing welded together. Some have used steel tubing with fittings bolted together. Aluminum is lighter but more expensive. Aluminum square tubing can be bolted or riveted together and some use round tubing welded together. Few cars are made from composites (fiberglass, carbon fiber or wood (the "natural . Bamboo has been used as a sustainable material.

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Mass of Materials

Electric Grinder
Screwing Nut on Bolt

Fasteners (Welding, Rivets, Bolts, Adhesives)

Need info

Safety, Frame, Drive System, Gearing, Weight and Balance

Balance
Screwing Car Wheel

Wheels, Brakes, Steering, Suspension

Designer's World

Planning

 
 
 
 
 
 
 
 
 

Cost and Schedule 

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Accounting Tasks
Presentation

Sourcing and BOM 

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Parts and  Materials

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Stacked Steel Rods
Engineering Sketch

Schematics

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Testing

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Male Scientist
Safety Goggles

Schematics 

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