Building an Electric Vehicle: Components and Construction Part 1: Volkswagen Conversion Part 2: Electric Go-Kart Race Michael D. Kane, PhD (1) Associate Professor of Bioinformatics (2) University Faculty Scholar (3) Chair of Graduate Education Department of Computer and Information Technology (4) Lead Genomic Scientist Bindley Bioscience Center at Discovery Park Purdue University West Lafayette, Indiana, USA evw.tech.purdue.edu

1. range: function of energy density of the battery. Compare 12,000 (theo.) / 2600 Wh/kg with the lead-acid 175 (theo.) / 35 Wh/kg 2. time to refuel: charge 40 kWh in 5 minutes? 220 V × 2200 A!!! When you pump 20 /min, your energy transfer rate is about 10 MW! (Hint: energy density of gasoline is 10 kWhth/.) 3. cost: (a) light but safe means higher materials costs, e.g., less steel, more aluminum; and higher processing costs, e.g., fewer castings, more forgings... (b) to reduce load on the battery requires high efficiency appliances = costly (c) low cycle life — batteries $4,000 to $8,000 lasting about 2 years Problems with EV propulsion

Specific Energies of Battery Chemistries (Wh/kg) (MJ/kg) lead acid NiCd NaS NiMH Li ion gasoline 12, NOTE: 1 Wh/kg storage capacity equals about 1 mile driving range

Specifications & Performance: Drive system: 72 volts (lead acid) Top Speed: 40 mph Distance: 25 miles Cost: $5,000 (total) Vehicle: $1,500 Batteries: $700 Electronics: $2,000 Batt Chargers: $500 Mechanical: $300

Original VW Motor:150 pounds (70 kg) 55 hp Conversion to Electric Motor: 70 pounds (30 kg) 27 hp* 200 pounds (90 kg) in batteries. Conversion is +120 pounds (55 kg) * The electric motor used in the conversion is rated at 15 hp (peak), but calculating horse-power in an electric motor is different than an internal combustion engine.

Contactor: A relay that closes the “drive batteries” circuit (i.e. turns the vehicle “on”) Throttle Box Controller Shunt

Throttle and Controllers

Configuration: 5 k ohm sealed pot without 3-terminal microswitch Conection: 4 foot long, 2-wire unshielded, #22 AWG cable Stroke: Spring-returned lever arm drilled for variable throw distances Metal Parts: Corrosion-resistant stainless steel Dimensions: 3.75" H X 4.00" W X 2.06" D Configuration : 5 k ohm sealed pot with 3-terminal microswitch Connectons: Potentiometer: 4 ft. long, 2-wire unshielded, #22 AWG cable Microswitch: Three 0.188" X 0.018" tabs Stroke: Spring-returned lever arm drilled for variable throw distances Metal Parts: Corrosion-resistant stainless steel Dimensions: 3.75" H X 4.00" W X 2.06" D Throttle Controls

Batteries : 6 x 12V lead-acid deep-cycle AND 1 x 12V for accessories

Controller Used in the VW conversion Used in the EV Go-Kart

Controller (Programmable through Software)

Electric Motor

Electric Motor Mount

Gauges

TESLA $110, hp EV-Bug $5, hp

Tesla Battery The pack weighs 990 pounds, stores 56 kWh of electric energy, and delivers up to 215 kW of electric power, 375 volts. Battery cost is about $30,000 Each cell is 18mm in diameter by 65mm length, The small cell size enables efficient heat transfer, allows for precise charge management, improves reliability, and extends battery pack life. Each cell is enclosed in a steel case which effectively transfers heat away from the cell. The small size makes the cell essentially isothermal, and its large surface area allows it to shed heat to the ambient environment. Sixty-nine cells are wired in parallel to create bricks. Ninety-nine bricks are connected in series to create sheets, and 11 sheets are inserted into the pack casing. In total, this creates a pack made up of 6,831 cells.

Chassis Motor mount added to rear Battery mounts added to sides of cart.

5 x 12V AGM Deep-cycle batteries in parallel

Some carts used lithium iron phosphate batteries (3.3 V)

Controller Power Switches Fuses Contactor

60V system with top speed of about 40 mph, endurance at about 40 laps.

Technology and Innovation On-board Camera GPS (speed) Lap-top to controller Blue-tooth helmet 1)Remote desktop to cart PC 2)Alter power settings during the race to optimize power/performance 3)Video feed sent to Jumbotron (entertainment) 4)Audio communications with driver