1. Battery Electric Vehicles

2. 2011 Nissan Leaf
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

3. Current vehicles in production
Nissan Leaf
Tesla S
Chevrolet Spark EV
Toyota RAV-4 EV
Ford Focus EV
Honda Fit EV
Smart EV
Fiat 500e

4. Nissan Leaf - General information
80 kilowatt electric motor /107 horsepower 280Nm/206 lbs-ft torque
Max motor speed 10,390 RPM
Operating range 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

5. Battery Charging

6. Receptacle cover release lever
Charging port
The charging receptacle is located on the out side of the vehicle usually near the front of the vehicle
Receptacle cover release switch may also be found on key fob
Receptacle cover release lever

7. Charging Sockets Two charging sockets:
Quick charge [DC]
J1772 [AC]
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
Image by Richard Kelly - via Wikimedia Commons

8. J1772 charging receptacle
Level 1 & 2 charging is done through a standardized 5 pin receptacle
Power
J 1772 is an SAE standard for BEV charging electrical connectors
Proximity [Safety]
Ground
Communications

9. Level 1 and Level 2 charging
Level 1 charging is done at 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 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

10. Level 1 charging cable
The Level 1 charging cord has a three prong plug that can connect to any volt outlet

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

12. 220 Volt Level 2 charging station
Inverter
Onboard charger
192 volts DC
HV Battery
220 volts AC
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

13. Charging 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
When only the left indicator is blinking the battery is less than 1/3 charged
Left indicator on – not blinking and the center lamp is blinking = 33% to 66% charged
Left and center on and right lamp is blinking = 66% to 99% charged
All 3 lights on solid = 100% charged
All lights are off when the charger is disconnected

14. 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
Residential Level 2 charging units normally have internet connectivity – this allows remote monitoring and scheduling of charging using any internet capable device.
Data

15. Fast DC charging
The Nissan Leaf and Mitsubishi i-MiEV have a CHAdeMO connector for fast DC charging
CHAdeMO is a Japaneese standard for high voltage charging – currently used by Nissan and Mitsubishi.
Charging is DC current – sent directly to the HV battery array and does not pass through the onboard charger.
Charging voltage can be as high as 480 volts DC.
Up to 40 amps max charging current.
Fast charging can bring the battery up to 60% SOC in about 30 minutes.
Nissan recommends that fast charging should only be done when overnight or trickle charging is not feasable
High voltage DC charging can be accomplished in 30 minutes

16. 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
This is the SAE / Euro alternative to the CHAdeMO socket.

17. 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

18. Battery temperature display
Range indicator
The right hand display shows how many more miles the vehicle can be driven
Battery temperature display

19. Driveline components

20. BEV electric drive system components
HV battery array
Electric motor [Traction motor]
Reduction gear unit + differential
Inverter
DC-DC converter
Onboard charger

21. Driveline components 2011-2012
DC-DC converter
Inverter
Charging connector
sockets
Gear reduction & differential
Traction Motor
On the Leaf the inverter is bolted to brackets on the unit body and the DC-DC converter is bolted to the firewall

22. HV Battery assembly
Inverter
DC-DC converter
Traction Motor
Note: The Leaf is unique in that it has no cooling system for the battery array.
Unlike a Chevy Volt there is also no heating system.
It may not be possible to drive a Leaf that has been parked outside in sub zero temperatures.
48 Li-Ion battery modules are located under the floor panel
The 392 volt battery module has no cooling system
Image courtesy of Nissan USA

23. HV Battery array
The 24 KWh Battery array consists of 48 modules that are enclosed in a steel clamshell case
HV battery control module
The clam shell battery case is designed to be air tight.
Pressure test ports on the top of the case are used to pressure test the seal between case halves after servicing.
An air tight seal is essential to ensure that no dirt or moisture contaminate the electrical connections inside the case
HV connection to inverter
Service plug socket
392 Volts DC at 80% SOC
Rubber gasket

24. Battery module
Each 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

25. 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
There is also a battery temperature in the B+ cable terminal for the 12 volt battery.
Temperature information from this sensor is used by the DC-DC converter to set the optimal charging voltage/amperage – like a voltage regulator does for an alternator.

26. 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

27. Mounting bracket for electric A/C compressor
Electric Motor
Mounting bracket for electric A/C compressor
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

28. Stator leads and resolver
Removing the rear cover reveals the stator lead attachments and the resolver
The resolver in this Leaf motor uses a 4 lobed eccentric

29. Gear reduction Unit
The gear reduction unit typically has a 8 to 1 speed reduction ratio
Parking pawl motor
Breather tube
The reduction unit contains a differential gearset that divides torque equally to the left and right drive wheels
The gear reduction unit holds 1.1 liters [1 ¼ qt] of Nissan Mattic fluid type S [Valvolene MaxLife]
An electric parking pawl motor locks the final drive when the shifter is returned to the park position

30. Output [Final drive] gear
Gear reduction unit
Input gear
Output [Final drive] gear
Idler gear
Unlike an internal combustion engine an electric motor can easily run backwards
When gear selector is placed in ‘R’ the traction motor reverses it’s direction of rotation
The reduction ratio is about 7.9 to 1.
At 60 MPH the traction motor is running a 6642 RPM.
This eliminates the need for a reverse gear

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

32. Parking pawl
Ratcheting Spring
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
Parking pawl
Linkage rod
connects to park motor
Parking gear
Intermediate
[Idler] gear

33. Motor and reduction unit
Earth brush cover
Reduction unit fluid drain plug
Radiators

34. Engine mounts and drive axles
The traction motor and gear reduction unit sit on rubber engine mounts in the same manner as an ICE motor and transmission
Inboard CV joint
Right side engine mount

35. 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

36. Ground brush holder There is no brush replacement interval
The brushes should last for the life of the vehicle

37. Inverter
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

38. Inverter -B +B U V
Stator W
The inverter used IGBTs to control the flow of current through each of the three stator coils

39. Inverter
The inverter’s sole function is to provide 3 phase AC current for the traction motor
The DC-DC converter is not integrated into the inverter as it is on most hybrids

40. 3 Phase HV cables
6mm bolts connect the 3 phase HV cables to the bus bars inside the inverter

41. 3 Phase HV cables
The 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

42. 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
12 volt battery + terminal
The DC-DC converter is located underneath the inverter
The DC-DC converter takes high voltage DC current from the HV battery array and changes it to 14 volts DC
Coolant tube
392 volt DC input terminals

43. 12 Volt battery
The 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

44. Hall effect current sensor
12 Volt battery
The battery cables connect the battery to the DC-DC converter
Hall effect current sensor
The negative battery cable is also connected to chassis ground
Both cable clamps have current monitoring sensors
The positive clamp also has an IR temperature sensor that monitors battery temp

45. 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

46. Onboard charging unit The charging unit is water cooled
Electrical noise filter unit
Coolant tube connections serviced from underneath the vehicle
Maximum charging rate is 3.3 Kilowatts

47. Electrical noise filter unit
Onboard charger
Electrical noise filter unit
The onboard charger has HV connections to the HV battery array and charging plug

48. 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

49. Reduction gears and differential
2013 Leaf drive train
Inverter
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
Onboard charger
Traction motor
Reduction gears and differential
Image courtesy of Nissan North America

50. High Voltage Cooling System

51. High voltage cooling system
Reservoir
EV Vehicle control module
Radiator
* Cooling fans not shown
On-board charger
Temperature signals
Electric pump #1
Electric pump #2
Inverter
Two electric pumps circulate coolant through all of the high voltage systems components
DC-DC converter
The system uses regular LLC coolant.
100,000 / 10 year change interval
The VCM – Vehicle Control Module monitors the temperature of all the HV components [Inverter, DC-DC converter, onboard charger and traction motor]
The VCM sends a PWM signal [Pulse width modulated] to each of the electric pump motors to control the speed of the pump motors – thus holding the temperature constant through all driving conditions.
The two electric fans have their own control module mounted on the back of one of the fan shrouds.
Since the system operates at relatively low temperatures it is not pressurized
Traction motor

52. A/C compressor mounting bracket
HV cooling system
Coolant inlet
A/C compressor mounting bracket
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 outlet
Traction motor

53. Coolant reservoir
The coolant reservoir has a conventional pressure cap
2011M/Y Leaf has a total coolant capacity of about 7 quarts
32 psi is the maximum pressure to be applied when testing the system for coolant leaks.

54. Bleeding the cooling system
On-board charger
The ‘Ready’ light must be on to enable the water pumps to circulate coolant trough the system
After filling the coolant reservoir open the bleeder tube at the bottom of the on-board charger [accessible from underneath the trunk]
Coolant inlet
Bleeder tube
Coolant outlet

55. Bleeding the cooling system
Open the connection in the cooling line behind the radiator support to bleed any air remaining in the inverter

56. Driving Controls

57. 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

58. Range indicator lights
Gear range selector
Parking brake Switch
Range indicator lights
Park, Forward [normal], Forward [ECON] and reverse ranges are selected by a an electric control switch which emulates a conventional gear selector

59. Instrument panel Regeneration Power Transmission range Ready light
Li-Ion battery Temp
Range

60. Upper instrument display
Accelerator pedal position
Clock
Outside air temp
Master warning indicator
When a tree symbol is illuminated inside the accelerator position indicator arc – ‘ECO’ mode is active
The speedometer and other indicators can be seen in a second display panel on top of the dash

61. 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
For example – if your driving in 30 degree ambient temperature – the cabin temp might be at 55 degrees. You’ll want to wear a sweater or light jacket – but your breath won’t freeze.

62. ECO Range
When ‘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

63. Electric Parking Brake

64. 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

65. Manual brake release socket
Actuator motor
Manual brake release socket
This design was necessary because the battery module occupies the entire center of the under floor area of the vehicle.
The only mechanical option would have been to mount the e-brake lever outboard of the driver seat [like Mazda did back in the 90’s] and run the cables down the left side rocker panel.
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

66. Parking brake manual release
Manual release access cover
A special t-handle tool included with the tire service tools is used to manually back off the brake cables

67. Heating and Air Conditioning System

68. Cabin heat system Cap Body control module Reservoir Heater core
PTC heater control signal
Heater core
12 volt electric pump
Temperature sensor
Since the coolant temperature should never come close to the boiling point the system does not need to be pressurized.
The reservoir [Nissan calls it a De-Gassing tank] is vented to the atmosphere through the overflow tube.
392 Volts DC
Drain valve
PTC Heater
High voltage battery array

69. PTC Heater
Note: when installed in the vehicle the high voltage cables are encased in an orange plastic harness sheath
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
Coolant outlet
Coolant inlet

70. PTC Heater
IGBTs
High voltage [392 volts] DC current is pulse width modulated by 4 IGBTs

71. Heater coolant reservoir
The PTC heater, electric water pump and temp sensor are located underneath the 12 volt battery
The system holds about 2 quarts of LLC coolant.

72. 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
The factory A/C charge does not include a fluorescent dye.
Nissan does not recommend adding dye to the system

73. Miscellaneous

74. No spare tire
An electric air pump plus a container of tire sealant is standard equipment
Eliminating the spare tire increases the vehicle’s rang by a mile or two
Since most electric vehicles will be driven no more than 20 miles from the owners home the lack of a spare tire, jack and lug nut wrench is not as important as it would be with a conventional ICE powered vehicle

75. Aerodynamics
The entire undercarriage of the vehicle is covered with flat plastic panels to help reduce aerodynamic drag
Image courtesy of Nissan USA

76. Service What else can we do…. Scheduled maintenance Brake service
Fluid levels, tire inspection and rotation etc 6K
Brake fluid replacement K
Coolant replacement K
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