The 2019 Kia Niro 64.8 kWh EV battery pack.
- Usable energy = 64.8 kWh (total = 68 kWh)
- Usable Window = 95.3%
- Nominal Voltage = 356 V
- Nominal Capacity = 180.9 Ah
- Configuration = 98s3p
- Peak Power = 150 kW10s
Across the parts you will see Kia and Hyundai logos.
The design and parts are all shared. The only difference is that the 2019 Hyundai Kona uses LG cells and the 2019 Kia Niro uses SK Innovation cells.
Charging
- Fast charging peak power = 77 kW
- 10 to 80% SoC = 44 minutes
Dimensions
- Pack Mass = 443 kg
- Cell Mass = 264 kg
- Pack-Cells = 179 kg
- Cell to Pack Ratio = 59.7%
Electrical
The battery pack has a total of 10 modules. Under the floor are 6 modules of 10s3p, under the back seat are 4 modules of 9s3p. Hence the total: (6 x 10 x 3) + (2 x 10 x 3 +2 x 9 x 3) = 294 cells.
The battery has a service disconnect that is located under the second row seat and below a removable panel.
The image below of the battery pack shows the position of the service disconnect on the top of the four rear modules. Also, in the image you can see a busbar that has a wider section, this is where they have incorporated an inline fuse.
The main fuse is in the plastic housing to the rear of the service disconnect, a 400A HRC unit, which is complemented with inline fusible links in the bus bars.
The service disconnect and 400A main fuse.
The inline fuse is within a section of the busbar.
Cooling
- Liquid cooling
The Niro/Kona uses cooling plates and a liquid coolant fluid. These plates cool the lower edges of the pouch cells that are arranged in 5 large modules and hence 5 cooling plates.
The two stacked modules at the rear of the pack appear to be fed from the two outer coolant plates in series.
The concern is that these two rear modules will see higher coolant temperatures than the 3 modules that run the length of the pack.
The two stacked rear modules are likely to age faster.
A section through the pack shows the thermal interface material (TIM) between the module and the cooling plate and the insulation under the cooling plate.
In total there is quite a lot of insulation material within this pack, or at least material that has a dual application as insulation.
The cooling plates have expanded polystyrene insulating strips underneath, isolating them from the casing.
The cooling channels are close together, each is about 20x5mm internal CSA with a 10mm gap between each channel, so there is a lot of coolant area in the plate. They have a putty type thermal paste which engages with the stainless thermal plates between each pouch cell, so there’s really good thermal coupling over the surface of the cell.
Each module has 2 temperature sensors.
So although there’s a long serial loop for the coolant I wonder if the flow is reasonable there may be an acceptable temperature gradient?
Thanks to Ralph Hosier from RHEL.co.uk for the insight.
Metrics
- Pack Gravimetric Energy Density = 154 Wh/kg
- Cell = 242 Wh/kg
- Pack Gravimetric Power Density = 339 W10s/kg
- Pack Continuous Power Density = 174 Wcont/kg
The continuous power density is based on the fast charge power of 77kW.
BMS
The Battery Management System (BMS) is a master slave design. The master sits in the front right hand corner of the pack enclosure and can be accessed via a hatch from underneath the pack/vehicle.
Two slaves sit at the front of the battery pack and three more are located on the front side of the rear stacked modules.
The sensor board runs down the end of the module.
At the front left hand corner of the battery pack is a leak detection sensor. Only one leak detection sensor is used in this pack design.
The sensor body is bolted to a bracket such that the sensor is flush with the inside lower surface of the enclosure.
A huge thank you to Ralph Hosier at RHEL.co.uk for supporting this post with data, knowledge and images.
Modules
As this is constructed using pouch cells it is necessary to apply a pressure to the surface of the pouch. This pressure is applied to ensure the active layers remain in contact over the lifetime of the product. In the image you can see the diecast aluminium endplates and the steel frame. Note that there is an upper and lower frame.
Note also how these upper and lower frames also locate and support the “Z” busbars that connect the sets of cells together in series.
This module design uses an “L” shaped heat transfer plate. This is not the most elegant or best method of edge cooling pouch cells.
The later Kia EV6 module improves on the design of the Niro in a number of areas.
Structure
In the front and mid-section of the pack you can see 4 tubes with sealing systems on the top. These allow 4 bolts to be inserted from the underside of the pack and to bolt into the underside of the body structure.
Mid-pack vehicle body mounts can be a really effective and efficient way to:
- Contribute to the stiffness and refinement targets of the vehicle.
- Increase the battery packs modal response to reduce energy input into the system through vehicle vibration. This in turn improves reliability & durability by reducing part displacement and fatigue-related failures.
As this particular design has limited cross-car load paths, I would also expect those mounting points were essential to meet some of the vehicle crash/service load cases as well.
This post has been built based on the support and sponsorship from: Eatron Technologies, About:Energy, AVANT Future Mobility, Quarto Technical Services, TAE Power Solutions and The Limiting Factor.
Cell
The pouch cell used in the 2019 Kia Niro is made by SK Innovation.
- Model = E600B
- Chemistry = NCM622
- Nominal capacity = 60 Ah
- Nominal energy = 3.63 V
- Nominal energy = 218 Wh
- Dimensions = 300 x 100 x 14mm
- Mass = 0.899 kg
References
- Kia niro batteries, DIY electric car