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Battery Electric Vehicles

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• The images and text of this presentation are based on a 2011 Nissan Leaf

• All modern battery electric vehicles used similar system components but there will be differences in appearance and location of those components

2011 Nissan Leaf

3Current vehicles in production

• Nissan Leaf• Tesla S• Chevrolet Spark EV• Toyota RAV-4 EV• Ford Focus EV• Honda Fit EV• Smart EV• Fiat 500e

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Nissan Leaf - General information• 80 kilowatt electric motor /107 horsepower

280Nm/206 lbs-ft torque– Max motor speed 10,390 RPM

• Operating range - 60 to 100 miles [depending on operating conditions, terrain and climate control settings]

• 24 KWh Li-Ion battery pack• 3.3 Kilowatt onboard charger• Max vehicle speed = 90 mph

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Battery Charging

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Charging port• The charging receptacle is located on the

out side of the vehicle usually near the front of the vehicle

Receptacle cover release lever

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Charging Sockets

• Two charging sockets: – J1772 [AC] is used for home charging at 110 or

220 volts AC– Quick charge port[DC] -sometimes referred to as

CHAdeMO connects to commercial high voltage DC charging stations

J1772 [AC]

Quick charge

[DC]

Image by Richard Kelly - via Wikimedia Commons

8J1772 charging receptacle• Level 1 & 2 charging is done through a

standardized 5 pin receptacle

Power

Ground

Proximity [Safety]

Communications

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Level 1 and Level 2 charging

• Level 1 charging is done at 110 -120 volts– A level 1 charging cable can be plugged into any

110 volt 3 pin electrical socket– Charging a Leaf at 110 volts will take 21 hours if

the battery is at 25% SOC

• Level 2 charging is done at 220-240 volts– A level 2 charging station is hardwired and

requires installation by licensed electrician– Charging at 220 volts reduces the Leaf’s

charging time to 7 hours

10Level 1 charging cable

• The Level 1 charging cord has a three prong plug that can connect to any 110-120 volt outlet

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Level 2 cable

The level 2 cable fits the same socket as the level 1 but uses 220 volt AC current

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Level 2 charging

• In both Level 1 and Level 2 charging the onboard charger converts AC current into DC current and steps up the voltage to the level needed to efficiently charge the batteries

220 Volt Level 2 charging station

Onboard charger

Inverter

HV Battery

192 volts DC

220 volts AC

13Charging indicator lights

• Most BEVs have an external indicator light that alerts the driver that the batteries have or have not been fully charged

• The batteries are fully charged when all 3 LEDs are illuminated

Battery charge

Indicator lamps

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Proximity pin

• The proximity pin on the j1772 socket tells the EV control module that the charging connector is plugged in

• This disables the park motor so that the vehicle cannot be moved while connected to the charger

• The data terminal allows serial communication between the charger and the vehicles control module

Proximity

Data

15Fast DC charging• The Nissan Leaf and Mitsubishi i-MiEV have

a CHAdeMO connector for fast DC charging

• High voltage DC charging can be accomplished in 30 minutes

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J1772 fast charging plug

• Chrysler-Fiat, Ford, GM, Audi, BMW, Daimler, Porsche and Volkswagen have chosen to use and updated j1772 plug for fast DC charging

• The plug hast the 5 pins for the level 1 & 2 AC charging socket plus two additional pins for high voltage [up to 500 volts] DC

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Fast charging and battery life

• Most manufactures recommend that fast DC charging should only be used in situations where a Level 1 or Level 2 charge is not an option

• Fast charging reduces the useable life expectancy of the battery – Since electric cars have only been available for sale

only few years the rate of battery deterioration has not been quantified

• If a brand new battery has a range of 100 miles [at 80% SOC] then when the battery at 80% SOC can drive the vehicle only 50 miles the battery has reached the end of its useable life

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Range indicator• The right hand display shows how many

more miles the vehicle can be driven

Battery temperature

display

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Driveline components

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BEV electric drive system components

• HV battery array• Electric motor [Traction motor] • Reduction gear unit + differential• Inverter• DC-DC converter• Onboard charger

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Driveline components 2011-2012

• On the 2011-2012 Leaf the inverter is bolted to brackets on the unit body and the DC-DC converter is bolted to the firewall

Traction Motor

DC-DC converter

Inverter

Gear reduction & differential

Charging connector

sockets

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HV Battery assembly

• 48 Li-Ion battery modules are located under the floor panel• The 392 volt battery module has no cooling system

Inverter

DC-DC converter

Traction Motor

Image courtesy of Nissan USA

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HV Battery arrayThe 24 KWh Battery array consists of 48 modules that are enclosed in a steel clamshell case

Service plug socket

HV connection to inverter

392 Volts DC at 80% SOC

HV battery control module

Rubber gasket

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Battery moduleEach module contains 4 cell pouches

Each cell develops about 4.0 volts at 80% SOC

Two pairs of two cells connected in parallel are combined to develop 8 volts at the module terminals

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Battery temperature

• There are four temperature sensors mounted inside the battery case

• The Li-Ion battery temperature is displayed on the left side of the instrument cluster

• If the battery temperature exceeds the critical limit the power output of the traction motor will be reduced and the heater or A/C functions will be minimal

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HV Battery removal

• The HV battery weighs about 800 lbs • A special hydraulic lift table and battery holding

fixture is required to service the battery

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Electric Motor

The Leaf has an 80 Kw [107 HP] electric motor

Most manufactures use a permanent magnet type motor

Only Tesla and Toyota [RAV-4 EV] use inductive motors

Mounting bracket for electric A/C compressor

28Stator leads and resolver

The resolver in this Leaf motor uses a 4 lobed eccentric

Removing the rear cover reveals the stator lead attachments and the resolver

29Gear reduction Unit

The gear reduction unit typically has a 8 to 1 speed reduction ratio

The reduction unit contains a differential gearset that divides torque equally to the left and right drive wheels

An electric parking pawl motor locks the final drive when the shifter is returned to the park position

Parking pawl motor

Breather tube

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Gear reduction unit

Input gearIdler gear

Output [Final drive] gear

When gear selector is placed in ‘R’ the traction motor reverses it’s direction of rotation

Unlike an internal combustion engine an electric motor can easily run backwards

This eliminates the need for a reverse gear

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Park motorPark is activated by an electric motor attached to the gear reduction unit case

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Parking pawl

• The parking pawl locks the idler gear so that it cannot turn

• The pawl is pushed by a spring when the park motor is engaged– If the vehicle is moving

the spring on the actuating rod will ratchet

– A loud grinding noise will be heard but no serious damage to the transmission [or gear reduction unit] will occur

Intermediate[Idler] gear

Parking gear

Linkage rodconnects to park motor

Ratcheting Spring

Parking pawl

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Motor and reduction unit

Reduction unit fluid drain plug

Earth brush cover

Radiators

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Engine mounts and drive axles

Right side engine mount

Inboard CV joint

The traction motor and gear reduction unit sit on rubber engine mounts in the same manner as an ICE motor and transmission

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Ground Brush

• The pulsating magnetic fields in the traction motor can induce small electrical currents in the motor shaft

• This electrical current will try to find ground through the gears and ball bearings supporting them

• The ground brush protects the gears and bearings by providing a safe path to ground

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Ground brush holder

There is no brush replacement interval

The brushes should last

for the life of the vehicle

37Inverter• The inverter is located

above the electric motor so that coolant can flow vertically from the motor to the coolant reservoir on top

• This allows any air bubbles in the cooling system to rise to the top of the reservoir

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Inverter

• The inverter used IGBTs to control the flow of current through each of the three stator coils

+B-B

U V

W

Stator

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Inverter

• The DC-DC converter is not integrated into the inverter as it is on most hybrids

The inverter’s sole function is to provide 3 phase AC current for the traction motor

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3 Phase HV cables• 6mm bolts connect

the 3 phase HV cables to the bus bars inside the inverter

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3 Phase HV cablesThe other end of the 3 phase cable is bolted to the top of the traction motor housing

The stator leads are connected to the 3 cable end terminals

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DC-DC converter

The DC-DC converter is located underneath the inverter

The DC-DC converter keeps the 12 volt battery

fully charged and provides all the electrical

current power for the lights, instruments and

accessories

The DC-DC converter takes high voltage DC current from the HV battery array and changes it to 14 volts DC

12 volt battery + terminal

392 volt DC input terminals

Coolant tube

4312 Volt batteryThe Leaf uses a conventional flooded cell lead acid battery to provide power for the computer system, lights and power accessories when the system is turned off

Removable cell covers

4412 Volt battery

The battery cables connect the battery to the DC-DC converter

Both cable clamps have current monitoring sensors

The negative battery cable is also connected to chassis ground

Hall effect current sensor

The positive clamp also has an IR temperature sensor that monitors battery temp

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Onboard battery charging unit• When the vehicle is connected to a 120 AC volt power source the onboard charger steps up the voltage to 192 volts and rectifies it into DC current

• When the vehicle is connected to 240 Volts AC the onboard charger steps down and rectifies the voltage to 192 VDC

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Onboard charging unitThe charging unit is water cooled

Coolant tube connections serviced from underneath the

vehicle

Electrical noise filter unit

Maximum charging rate is 3.3 Kilowatts

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Onboard charger

• The onboard charger has HV connections to the HV battery array and charging plug

Electrical noise filter unit

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Onboard charger coolant lines

• Coolant lines connect the onboard charger to the radiator

Coolant tubes HV Cable to charger plug receptacle

Note: HV battery has been removed

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2013 Leaf drive train

For MY 2013 the charger has been moved to the front and sandwiched between the inverter and motor housing

All 4 major components are now bolted together

Image courtesy of Nissan North America

Inverter

Onboard charger

Reduction gears and differential

Traction motor

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High Voltage Cooling System

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High voltage cooling system

Two electric pumps circulate coolant through all of the high voltage systems components

EV Vehicle control module

Radiator* Cooling fans

not shown

ReservoirOn-board charger

Electric pump #1

Electric pump #2

DC-DC converter

Inverter

Traction motor

Temperature signals

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HV cooling system

• The HV cooling system circulates coolant in series - through the on-board charger, DC-DC converter, inverter and traction motor

• The coolant is a 50/50 solution of long life antifreeze and water

Coolant inlet

Coolant outlet

Traction motor

A/C compressor mounting bracket

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Coolant reservoir• The coolant reservoir

has a conventional pressure cap

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Bleeding the cooling system

After filling the coolant reservoir open the bleeder tube at the bottom of the on-board charger [accessible from underneath the trunk]

Bleeder tube

The ‘Ready’ light must be on to enable the water pumps to circulate coolant trough the system

On-board charger

Coolant outlet

Coolant inlet

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Bleeding the cooling system

Open the connection in the cooling line behind the radiator support to bleed any air remaining in the inverter

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Driving Controls

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Start Switch• Like most modern

cars the Leaf uses an RF key fob instead of a key

• To start the vehicle press the start switch and check the ‘Ready’ light on the instrument panel to make sure the vehicle is operating

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Gear range selector

• Park, Forward [normal], Forward [ECON] and reverse ranges are selected by a an electric control switch which emulates a conventional gear selector

Parking brake Switch Range indicator

lights

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PowerRegeneration

Transmission range

Ready light

Li-Ion battery Temp

Instrument panel

Range

60Upper instrument display

• The speedometer and other indicators can be seen in a second display panel on top of the dash

Accelerator pedal position

Clock

Master warning indicator

Outside air temp

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Accessory drains

• Using the heating or air conditioning system will decrease the usable range of the battery

• When ‘ECON’ range [gear selector] is selected peak power is reduced and the AC and heat system functions at peak efficiency but the cabin temperature may be less than ideal

• The range display value will change when the shifter is moved in and out of ‘ECON’ or the AC/Heat is turned on and off

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ECO RangeWhen ‘ECO’ is displayed on the instrument panel the vehicle is in DRIVE and the VCM is program to adjust the power output and climate controls for maximum driving range

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Electric Parking Brake

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Electric parking brake actuator

• The parking brake is applied and released by means of an electric actuator motor

• Two parking brake cables connect the actuator motor to the rear brake calipers

• A switch at the rear of the console activates the motor

65Actuator motor

• The parking brake actuator motor is mounted beneath the trunk and connected by cables to the calipers

• An manual release cable allows the parking brakes to be released if the motor fails or the 12 volt battery is discharged

Manual brake release socket

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Parking brake manual release

• A special t-handle tool included with the tire service tools is used to manually back off the brake cables

Manual release access cover

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Heating and Air

Conditioning System

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Cabin heat systemBody

control module

Heater core

High voltage battery array

PTC Heater

Temperature sensor

Drain valve

12 volt electric pump

Reservoir

Cap

PTC heater control signal

392 Volts DC

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PTC Heater

Coolant is electrically heated by PTC [Positive Temperature Coefficient] resistors

The PTC heater may use up to 5000 watts of electric power

Up to 12 liters per minute of heated coolant can be pumped through the heater system

Note: when installed in the vehicle the high voltage cables

are encased in an orange plastic harness sheath

Coolant inlet

Coolant outlet

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PTC Heater

• High voltage [392 volts] DC current is pulse width modulated by 4 IGBTs

IGBTs

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Heater coolant reservoir

• The PTC heater, electric water pump and temp sensor are located underneath the 12 volt battery

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Air conditioning system

• The A/C system is a conventional TXV system with the exception of an electrically driven scroll type compressor

• The inverter for the compressor is located inside the main inverter case

• Like all electric A/C compressors only ND-11 type refrigerant oil can be used

• An electronic refrigerant pressure sensor monitors system high side pressure

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Miscellaneous

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No spare tireEliminating the spare tire increases the vehicle’s rang by a mile or two

An electric air pump

plus a container of tire sealant is standard equipment

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Aerodynamics

The entire undercarriage of the vehicle is covered with flat plastic panels to help reduce aerodynamic drag

Image courtesy of Nissan USA

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Service

• Scheduled maintenance– Fluid levels, tire inspection and rotation etc 6K– Brake fluid replacement 12K– Coolant replacement 125K

• What else can we do….• Brake service• Because the hydraulic brakes are not used as

much as a convention vehicle expect problems with frozen caliper slide pins etc.

• CV joints, ball joints, tires and other suspension services will needed just like any other vehicle