2015 Nissan Leaf

Nissan increased the battery capacity from 24kWh to 30kWh with a change in cell supplier. An increase in cell energy and moving from a 4 cell module to an 8 cell module allowed this energy to be contained in the existing case.

This meant the overall battery package was the same shape with an ~21kg increase in weight.

Details of this LG Chem cell and it’s application in the Nissan Leaf are difficult to find.

Specifications:

• total energy = 30.8kWh
• usable energy = 27.7kWh
  • Usable SoC = 90%
• peak discharge ~90kW_10s
• continuous power
• nominal voltage = 360V
• capacity = 86Ah
• voltage range = 240V to 398V
• weight = 315kg
  • cells = 185.5kg
• volume pack = litres
• pack dimensions [m] =
  • module =
• number of cells = 192
  • 96s
  • 2p
• charge time = 80% in 30 minutes
  • max charge power = 50kW
• modules:
  • 24 modules in total (compared to 48 used in original 2011 Leaf)
  • 8 cells per module
• cooling system = passive

Passive cooling means that this battery gets hot and in hot climates it stays hot. Hence in hot climates the pack can age much faster.

• cell make and model
  • LG Chem LQ 1729-A2
    • Capacity = 43Ah
    • Nominal voltage = 3.73V
    • Maximum voltage = 4.15V
    • Minimum voltage = 2.5V
    • Cell weight = 0.966kg
    • Format = pouch cell

This was a change from the AESC cell and appears to have been used jointly by Renault and Nissan. Our assumption is this was a drive to reduce costs by sharing technology across multiple car-lines.

• pack cost = ?

Key Pack Metrics:

• Gravimetric energy density, pack = 97.8Wh/kg
  • Cell = 166Wh/kg
• Volumetric energy density, pack = Wh/litre
• Gravimetric power density, pack = 286W/kg_10s
• Volumetric power density, pack = W/litre_10s
• Estimated cost = $/kWh
• Cell to Pack mass ratio = 59%
  • module to pack mass ratio = %
• Cell to Pack volume ratio

Other key features:

• Safety
• BMS
• HV Distribution
• HV and LV Connections
• Cooling Connections – none as this is passively cooled
• Structural / non-structural pack
• Case material = steel clamshell design
• Sealing strategy
• Venting strategy
• Durability
  • failures in 30kWh cars that we already know about have started appearing when the vehicles were only a year or two old and often with very low odometer readings [3]
  • sometimes multiple pairs of cells show very low state of charge the BMS (known as the LBC in the Nissan batteries) can only achieve a limited amount of cell balancing and hence not able to recover the SoC of these cells
    • suspected to be a defect created at some time during the cell’s manufacturing process

While it took 4.6 years for the 24 kWh Leafs to reach a mean 85% SoH, the 30 kWh Leafs reached this in 2.1 years.

Daniel Myall, Dima Ivanov, Walter Larason,
Mark Nixon, Henrik Moller, “Accelerated reported battery capacity loss in 30 kWh variants of the Nissan Leaf“, PrePrints

At two years of age, the mean rate of decline of SoH of 30 kWh Leafs was 9.9% per annum, around three times the rate of decline of 24 kWh Leafs which at two years averaged 3.1% per annum.

In June 2018 Nissan released a service campaign for its UK and USA customers, where the firmware of the car’s LBC can be upgraded in 30 kWh cars manufactured from December 2015 to August 2017. The upgrade applies to LBC firmware versions ending in 4A, 4B, 5A and 5B.  This update purports to correct the reported State of Health (SoH) of the car and correct the underestimation of range. 30 kWh Nissan Leaf firmware update to correct capacity reporting

This shows that the LG Chem cells in the 30kWh pack were not degrading faster than the AESC cells in the original 24kWh pack, but that there was a systematic bias in the BMS SoH algorithm and hence it was reporting the wrong State of Health.

• Warranty
  • The same nine out of 12 battery health bars caveat remained but the warranty now lasted for eight years or 100,000 miles.
• Availability
  • Replacement packs are available from EV Baltic.
• Recycling
  • Nissan have trialed second life for battery packs and modules.
• Shipping

References

1. Daniel Myall, Dima Ivanov, Walter Larason, Mark Nixon, Henrik Moller, “Accelerated reported battery capacity loss in 30 kWh variants of the Nissan Leaf“, PrePrints
2. BuyaCar – Nissan Leaf Batteries – overview of the warranty on the first 2 generations of the Leaf
3. EVs Enhanced – 30kWh Leaf Cell Imbalance and Complete Cell Failure
4. Open Vehicles – Nissan Leaf/e-NV200
5. EV Baltic – 30kWh replacement Leaf battery pack
6. Recurrent – Used Nissan Leaf Range and Battery