Building an Electric Vehicle:Components and Construction

Part 1: Volkswagen ConversionPart 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 ScientistBindley Bioscience Center at Discovery Park

Purdue UniversityWest Lafayette, Indiana, USA

evw.tech.purdue.edu

1. range: function of energy density of the battery.Compare gasoline @ 12,000 (theo.) / 2600 Wh/kgwith the lead-acid battery @ 175 (theo.) / 35 Wh/kg

2. time to refuel: charge 40 kWh in 5 minutes?220 V × 2200 A!!!When you pump gasoline @ 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 priced @ $4,000 to $8,000lasting about 2 years

Problems with EV propulsion

Specific Energies of Battery Chemistries

(Wh/kg) (MJ/kg)lead acid 35 0.13NiCd 45 0.16NaS 80 0.28NiMH 90 0.32Li ion 150 0.54gasoline 12,000 43

NOTE: 1 Wh/kg storage capacity equals about 1 mile driving range

Specifications & Performance:

http://evw.tech.purdue.eduDrive system: 72 volts (lead acid)Top Speed: 40 mphDistance: 25 milesCost: $5,000 (total)

Vehicle: $1,500Batteries: $700Electronics: $2,000Batt Chargers: $500Mechanical: $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 cableMicroswitch: 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$110,000

270 hp

EV-Bug$5,00027 hp

Tesla BatteryThe 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 CameraGPS (speed)Lap-top to controllerBlue-tooth helmet

1) Remote desktop to cart PC2) Alter power settings during the race to optimize power/performance3) Video feed sent to Jumbotron (entertainment)4) Audio communications with driver