2. The Basics:
• EV: electric vehicle
• Are EV’s practical? Golf courses and
airports have thought so for many years.
• But what about on the road? Are there EV’s
among us? Yes, and not just in California!
• Is there actually technology available to
you and me to allow us to operate a
practical EV? Yes!
3. OEM EV’s (you may have heard of
some of these):
• GM EV1
9. Components
• What is out there that you need to have to
build an EV (besides batteries)?
– Motor
– Controller
– Charger
– DC/DC Converter
– Heater
– Instrumentation
– Contactor(s)
– Safety Equipment
10. Motors
• OEM’s: typically AC drive
– Fail-safe design
– Low initial torque, higher at speed
– requires complicated electronics package
• AC speed control (similar to industrial)
• Inverter (convert DC to AC)
• High voltage (240-350 VDC)
• Bearings only mechanical maintenance item
11. Motors
• Hobbyist: typically brushed DC series
wound
– Motors are available and inexpensive
– 100% torque at 0 RPM
– Controllers are dirt cheap compared to AC
– No inverter stage required
– Lower voltage system (72-156 VDC)
– Bearings and brushes are potential
maintenance items (change brushes every
100,000 hours or so)
15. Chargers
• OEM: uses weird connectors like inductive
“paddle” or AVCON “gas pump” nozzle.
• Hobbyist: How about something everyone
already has, like 120 VAC household outlets
and 240 VAC dryer outlets?
• Simple (voltage regulated) to complicated
(computer controlled charging algorithms)
• More advanced charging required for
advanced batteries (AGM)
16. DC/DC Converters
• Uses PWM to step traction pack voltage
down to 12V to run car accessories.
• Common in electronics use
• Not widely available in the voltages
required
17. Heater
• Ceramic - Self-regulating temperature of
about 180° F.
• As temp. increases, resistance increases,
decreasing power and stabilizing temp.
• Therefore, more air across the element =
more heat.
• Typically 1500W. Can be stacked for more
heat.
19. Instrumentation
• Instrumentation can be as simple as an
expanded scale voltmeter, but can be
sophisticated, and include:
– Traction Pack Voltmeter
– Battery Current Ammeter
– Motor Current Ammeter
– Amp-hour/kWh meter (“E-Meter”)
21. Safety
• Inertia switch to deactivate contactor(s)
– same as is used to shut off fuel pumps in ICE
cars
• AGM batteries - no spillage
• Service disconnects - BIG circuit breakers
• Fuses, of course
• Traction pack is electrically isolated from
frame
• 8 G crash load rating recommended for
battery boxes
22. Performance
• Acceleration and speed
– About the same as ICE
– Ranges from “economy car” to “muscle car”.
– DC motors great for drag racing
– Current NEDRA record 8.801 seconds in the 1/4
mile by “Current Eliminator”
24. Performance - tZero
• AC Propulsion's tzero out-accelerated a
Ferrari F355, a new Corvette, and a Porsche
Carrera 4 in a series of impromptu 1/8 mile
drag races held on January 22, 2000 at
Moffett Field in Mountain View, California,
and at Calstart's northern facility at the
former Alameda Naval Air Station.
25. Performance - tZero
• tZero mfg. By AC Propulsion versus Corvette
tzero_corvette_drag1.mov
26. Performance
• Range - typically 30-60 miles
– somewhat dependent on if you have a lead foot
– great for commuting, which is where people
use the most gas anyway.
– Use an ice vehicle for long trips - the right tool
for the right job.
• Over 100 miles attainable with purpose-
built EV’s or using advanced batteries
29. Emissions
• Common claim is EV’s just move the
pollution
• Point taken, but power plant emissions are
scrubbed to a point not possible on a
vehicle.
30. Emissions
• Belfast electric bus project (4 year
duration of monitoring)
Fuel Consumed (kWh/mile)
Diesel Electric Savings
4.9 2.2 55%
Pollutants (gms/mile)
Diesel Electric Savings
CO2 1331 1058 21%
CO 7.64 0.18 98%
NOx+SO2 19.96 11.52 42%
Hydrocarbons 2.74 0.18 93%
Particulates 5.1 0.2 96%
