Nissan Leaf teardown (Part 1)

Benchmarking systems and components for EV

2012/03/05

Summary

On December 12, 2011, benchmarking was conducted in which Nissan's volume production electric vehicle, the Nissan Leaf EV, was disassembled and all its systems and components exposed. Benchmarking, organized by the Next-generation Automobile Support Center of the Saitama Industrial Development Corporation, was performed by the students of the Saitama Institute of Automotive Technology located in Ina, Kita Adachi-gun, Saitama Prefecture.

All parts and components having something to do with EV systems were separated from the vehicle and disassembled into individual units and components. Benchmarking did not involve further disassembly of removed parts or removal of sections that had nothing to do with EV systems, such as the interior equipment.

This report contains description of systems and parts in the order they were disassembled.



Nissan Leaf specifications

Model name: Nissan ZAA-ZE0
Size: Overall length 4,445 × Width 1,770 × Height 1,545mm, Wheelbase 2,700mm
Weight: Vehicle weight: 1,520kg, Gross vehicle weight: 1,795kg
Body: Five-door hatchback
Performances: JC08-mode AC power consumption: 124Wh/km, JC08-mode cruising range: 200km/charge



Main parts and their suppliers

Part name Supplier Location
EV system parts Power motor (3-phase AC synchronous motor, maximum output 80kW, maximum torque 280N・m) EM61 type In-house supply by Nissan Motor's Yokohama Plant Motor room
Inverter (IGBT x 6) In-house supply by Nissan Motor /Calsonic Kansei Motor room
DC-DC converter (doubles as a junction box) Denso Motor room
Power transmission system (reduction gear, reduction ratio: 7.937, without gear-shifting) model: RE1F61A Aichi Machine Industry Motor room
Lithium-ion battery module (total voltage: 360V, capacity 24kWh, output 90kW or higher) AESC Automotive Energy Supply Underfloor
BMS (Battery Management System) Calsonic Kansei In Li-ion battery module
Collision detection system Panasonic In Li-ion battery module
Onboard charger (input voltage: 100VAC~264VAC, output: 3.3kW maximum) Nichicon Cargo room
Noise filter (charging noise suppressor) - Cargo room
Auxiliary devices other than EV systems A/C electric compressor Panasonic Cargo room
PTC heater (hot water 350V, 4.0kW, 5.0kW in cold areas) Eberspaecher (Germany) Motor room
Water pump for heaters Nitto Denko Motor room
Proximity warning system Panasonic Motor room
Capacitor (electrically-controlled brake backup power unit, power supply when 12V battery goes low) Panasonic Cargo room
ECU for electric parking brake Advics Cargo room
Electric parking brake, actuator (fitted to transmission) Denso Cargo room



Nissan Leaf EV system diagram and sequence of disassembly

Disassembly work was performed in the order shown below:


Removal work took place in three blocks as shown above: 1) steps ① to ④ in the motor room (equivalent to the engine room on engine-powered vehicles), 2) step ⑤ involving the battery unit under the floor, and 3) step ⑥ involving the charger and auxiliary systems in the cargo room.

Removal of the lithium-ion battery module under the vehicle floor, front end, tires and other exterior components was omitted as they had been completed earlier.

* Click on the photo for a larger image.

Disassembly and removal work in progress
Drive units (electric motor, power transmission system, drive-shafts etc.) being lowered from the vehicle

Views of the motor room
From above the motor room From lower rear of the motor room
View from above the motor room. Vehicle front to the right. The unit with "Nissan" logo is the inverter. The DC-DC converter is seen behind.
The power motor, power transmission system and other drive units are under the inverter.
View from the lower rear of the motor room. Vehicle's right-side seen to the right and the vehicle front in the background. The power motor in the foreground and the integrated power transmission system (reduction gear) seen to the left. The drive-shaft extending from the power transmission system is seen at the top.

① Motor room - Inverter and charging port removal

Removing the inverter With the inverter removed
After the inverter was removed, the side of the DC-DC junction box, normally located behind the inverter, is seen to the left. The 3-prong orange-colored coupler at the center is a high-voltage cable that connects the power motor and the inverter. The orange-colored cables to the right are the high-voltage cables from the charging ports in the vehicle's front end.

Inverter Inverter (view from rear)
Inverter supplied by Calsonic Kansei (view from front). Nissan's in-house supplied inverters are also used.
The bulge for cooling water hose connection is seen in the front left.
Inverter (view from rear)

Charging ports Normal(Level 1/2) and quick charging ports
Charging ports with bumper units removed.
The orange-colored cap to the right is the normal charging port. The larger one to the left is the quick charging port.
Normal and quick charging ports removed from the vehicle.
The normal charging port is connected to the onboard charger located in the cargo room where current is rectified and supplied to the DC-DC converter located in the motor room (this means the high-voltage cable runs to the cargo room and returns to the motor room).
The quick charging port connects directly to the DC-DC converter.

② Motor room - Drive unit removal

Drive unit viewed from vehicle front Drive unit
The drive unit is seen from the vehicle front after the charging ports are removed and the radiator and the cooling system for the A/C condenser are taken away.
The A/C electric compressor is seen in upper left, the power motor under the compressor, and the power transmission system (reduction gear) directly coupled to the right of the motor.
In this report, the "power unit" refers to the power motor integrated with the power transmission system. The "drivetrain" refers to the drive-shaft, hub etc., that are connected to the power transmission system. "The drive unit" refers to the power unit and the drivetrain.
The drive unit lowered from the vehicle (view from front left of the vehicle). The power transmission system (reduction gear) is seen in the foreground.
The orange-colored 3-prong coupler is the high-voltage cable that connects the power motor and the inverter.

Main components of the power unit
Drivetrain and power unit Power motor and power transmission system
Drivetrain (foreground) separated from the power unit (background). Power motor (left) and the power transmission system (right) with the electric compressor removed (separation and disassembly of the motor and the power transmission system was not performed in the benchmarking).
The power motor is a 3-phase AC synchronous motor with 80kW maximum output and 280N・m maximum torque. In-house production at Nissan Motor's Yokohama Plant.

Front (when mounted) of the power motor Shaft connector of the power transmission system
The motor type "EM61" engraved in the front of the power motor (as mounted). Shaft connector of the power transmission system with the drive-shaft removed (vehicle left).
The power transmission system (RE1F61A supplied by Aichi Machine Industry) does not have a gear-shifting mechanism. It is a reduction gear with the reduction ratio of 7.937 and is designed to suppress torque loss during the high-speed revolution of the motor.

Electric parking brake and actuator A/C electric compressor
Electric parking brake and actuator (mounted over the power transmission system), supplied by Denso.
The electric parking brake ECU (supplied by Denso) is located in the cargo room.
A/C electric compressor (supplied by Panasonic).
Mounted by direct coupling over the power motor.
On engine-powered vehicles, the compressor is driven by the engine. On Nissan Leaf EV, the compressor is driven by high-voltage power supplied by the DC-DC converter rather than by the power motor.

③ Motor room - DC-DC converter removal

View from lower front of the vehicle
with the drive unit removed
DC-DC converter (passenger compartment side)
View from the lower front of the vehicle with the drive unit removed reveals how the DC-DC converter is mounted and the high-voltage cable routed. The power units such as the power motor, power transmission system and the inverter are mounted via the drivetrain members. The DC-DC converter is mounted to and protected by a sturdy member frame for greater crash safety.
The DC-DC converter (supplied by Denso) is also called a DC-DC junction box as it serves as a gateway of high-voltage cables.
The cable at the center of the photo running to the back (vehicle rear) is for the battery module connection. The cable running from right to the back (vehicle rear) is for the connection from the DC-DC converter and the normal charging port to the onboard charger in the cargo room.
The two cables running from the front of the DC-DC converter in the right front of the photo are connected to the quick charging port. The cable running from the center front to right is for power supply to the PTC heater.
View from vehicle rear (passenger compartment side) of the removed converter.
The high-voltage coupler at the lower center of the photo is the connection harness to the lithium-ion battery module.
The fixture in the upper right is the connection bulge for the converter cooling water hose.

④ Motor room - Auxiliary system removal

Water pump for the heater, PTC heater PTC heater
The heater water pump (round part at upper center) and the PTC heater (box-like part underneath) are shown as mounted (view from vehicle right). PTC heater removed from the vehicle (view from top as mounted).
The PTC heater with 350V and 4.0kW ratings (5.0kW in cold areas) is manufactured by Eberspaecher, a German corporation.
On engine-powered vehicles, the engine's cooling water is used as the heat source of the heater. On Nissan Leaf EV, the high-voltage power supply from the DC-DC converter is used to heat the water using the PTC element. The hot water is circulated by the water pump.

Pump for circulating hot water to the heater 12V storage battery
Pump for circulating hot water to the heater (supplied by Nitto Denko) The 46B24L type 12V storage battery (mounted in rear left of the motor room).
In addition to the lithium-ion battery, the Nissan Leaf EV uses conventional 12V lead storage battery to operate the wiper motor and other 12V-driven electric devices. The 12V power is provided by transforming the high-voltage power from the lithium-ion battery by the DC-DC converter.

Proximity warning system
The proximity warning system (supplied by Panasonic) audible alerts pedestrians that the vehicle is approaching (as mounted).

Body bottom
Views of the underfloor with the lithium-ion battery module removed
Views of the underfloor with the lithium-ion battery module removed (vehicle front to the left).
Space in the right and left sides running front to rear of the vehicle is used to stow the front module stack (12 battery packs in the module front are stowed in the right and left sides each).
Views of the underfloor with the lithium-ion battery module removed (vehicle rear to right).
Space extending right and left is used to stow the rear module stack (24 battery packs in the module rear).
The orange-colored cable in the foreground is the high-voltage cable that connects the onboard charger in the cargo room to the DC-DC converter in the motor room and the normal charging port in the front end.
The two metal pipes in the center are the water feed and return pipes for cooling the onboard charger.

⑤ Lithium-ion battery module removal

Inner view of the battery stack
Inner view of the battery stack (view from vehicle front when mounted).
The entire battery module weighs 294kg and measures 1,188 (W) x 1,570 (L) x 265mm (H). The orange-colored coupler in the foreground is the receptacle for the high-voltage cable from the DC-DC converter.
The flat-stowed battery packs in the right and left sides in the foreground are the front module stacks, 12 of them in each side. The vertically stowed battery packs in the background are the rear module stacks (24 battery packs). The 48 packs in total provide the rated 360V output. The battery packs are supplied by AESC Automotive Energy Supply.
The black module in the center foreground (between the flat-stowed packs) is the collision detection system (supplied by Panasonic). The system interrupts high-voltage power when it detects collision.
The white box in back of the collision detection system contains a service plug of the SD/SW (service disconnect switch). When the power switch in the driver's seat cannot be turned off or when the high-voltage power interruption fuse cannot be accessed as the bonnet hood in the motor room cannot be unlocked after an accident or for other reasons, the SD/SW is accessible when the floor in the vehicle rear section is opened. The high-voltage circuit will be shut down when the plug is removed.

Cover removed from the battery stack Service plug coupler of SD/SW
Cover removed from the battery stack (view from front when mounted).
The raised section in the background is the rear module stack area where a total of 24 battery packs are vertically stowed.
The central opening is provided to route the service plug of the SD/SW (service disconnect switch) through to under the rear floor.
Service plug coupler for SD/SW (service disconnect switch)

Collision detection system
Collision detection system, covered for protection, with battery stack mounted.
(View from the vehicle front when mounted)
Collision detection system (removed from battery stack and uncovered).
A pair of detectors is used (supplied by Panasonic).
(View from the vehicle front when mounted

BMS battery management system BMS mounting position viewed from rear
BMS battery management system (supplied by Calsonic Kansei).
BMS manages and controls charge/discharge of the lithium-ion battery.
BMS is mounted to the left of the rear module stack (shown in the right-hand photo with the BMS removed).
BMS mounting position viewed from rear when mounted to the rear module stack (fitted using the bracket at far-left of the battery pack in the foreground).

Rear module stack removal Harness from battery pack to BMS
The rear module stack consisting of 24 battery packs being removed. Harness exiting from the lower battery pack is a temperature sensor (found in each stack). The measurement is sent to the BMS (the front module stack is shown here).
Each battery pack contains four pieces of thin laminated sheet cells (not disassembled during the benchmarking).
The 48 packs with 192 cells in total provide the rated 360V output.

Couplers removed from battery packs
Couplers removed from battery packs.
Couplers for rear module stack (top) and couplers for front module stack (bottom).

⑥ Cargo room - Onboard charger and electric component removal

Onboard charger and other equipment mounted between the rear seat and the cargo room Components in the cargo room uncovered
The onboard charger and some other equipment are mounted between the rear seat and the cargo room.
They are shown from the vehicle front with the rear seat and covering removed (the rear seat in the foreground, the cargo room in the background).
Shown in the photo are, from left to right, the onboard charger (large metal chassis), noise filter (white), capacitor (black square, electrically controlled brake backup power unit) and the ECU for electric parking brake (brown) located under the capacitor.
Components in the cargo room are shown uncovered (view from vehicle rear, the cargo room in the foreground and the rear seat in the background).
Shown in the photo are, from right to left, the onboard charger, noise filter, capacitor and protective bar (black rod-like part running across) against rear collision.

Onboard charger in the cargo room
behind the rear seat
Capacitor
The onboard charger (supplied by Nichicon) in the cargo room behind the rear seat and the noise filter that suppresses charging noise in the foreground (vehicle front to the left with the rear seatback, and the cargo room to the right).
The commercial AC power fed from the normal charging port is rectified from AC to DC by the onboard charger and sent on to the DC-DC converter in the motor room.
Capacitor (electrically-controlled brake backup power unit, supplied by Panasonic) supplies necessary auxiliary power for the electric brake in the event the 12V battery power goes low. The capacitor has no direct involvement with the EV control systems.

ECU for electric parking brake Equipment in the cargo room
ECU for the electric parking brake (supplied by Advics) is mounted in lower front of the capacitor. The electric parking brake is mounted over the transmission in the motor room. Equipment in the cargo room removed together with the bracket.
Shown are, from left to right, the onboard charger, noise filter and capacitor (electrically-controlled brake backup power unit).

⑦ Overall - Removal of parts

Future service pros of the Saitama Institute of Automotive Technology
that performed benchmarking overlooking the removed parts

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