One of the most important challenges in the development of electric drives is the thermal management of batteries. It is crucial for:

• the range of the vehicle
• the service life of the batteries
• fast charging

Columbia-Staver Design Flexibility

 Because of the variety of cell shapes and more importantly the different temperature distributions within the cells, thermal management solutions need to be flexible.

Columbia-Staver has developed a technology that can not only adapt to the cell and module shape but can also target the coolant directly at the cell’s hot spot.

Lightweight aluminium Cold Plates can be custom-sized to match the selected cells and the liquid flow path customised for optimum cooling of the cell’s hot spots.

 

Inter-leaved system for the cooling of pouch cells.

Coolant is targeted at the cell hot spots between the terminals.

Coolant is fed from and returned to the cooler by tubes and distributed within the Module by manifold runners.

 

 

 

Inter-leaved system for the cooling of prismatic cells.

Coolant is targeted at the cell hot spots between the terminals.

Coolant is fed from and returned to the cooler by tubes.

 

 

System designed for cooling LTO cylindrical cells. Cells are inter-leaved with cold plates and coolant is targeted at the hot spot between the terminals. System inter-connection is via tubes.

 

 

 

Cylindrical cell cooling solution. The cell’s hot spot is in direct contact with the cold plate.

 

 

Isothermal cold plate
Columbia Staver Ltd have designed a cold plate that can significantly reduce the delta T between individual battery cells. The Isothermal cold plate has the inlet and outlet on the same end of the plate. The inlet and outlet connectors can be customer specified and can be in line with or at 90° to the manifold.

The flow path within the plate is through a custom extrusion designed to the customer’s specified width and length. This design can be customised to enable the Cold Plate to become the central component in a complex battery pack assembly.

The internal geometry within the manifold controls the flow of coolant into the channels of the extrusion. When analysed by advanced CFD the standard geometry offers very good isothermalisation. However, customers have different design requirements and cooling challenges.

Using the CFD software the geometry within the manifold can be adjusted and this subtly changes the pressure distribution and hence the balance of the liquid flowing down specific channels within the extrusion.

Shown in the images below is an example, the image on the left shows the results with the standard internal geometry. After running the CFD optimisation program 15% of the cells showed an improvement of 1°c and 75% of the cells improved by 0.5°C. This improvement can be seen in the image on the right.

Production

These Isothermal cold plates have been designed for high volume production, that’s why the flow path is a custom designed extrusion. Columbia-Staver recognise that in the early stages of a project where small volumes of prototypes might be required, paying for a custom extrusion tool might prove to be prohibitive.

Columbia-Staver can manufacture by CNC machining and brazing a flow path that will exactly replicate the form fit and function of the extruded part:

 

 

Stamped and Bonded cold plates.

These cold plates can be designed to cool cylindrical, prismatic and pouch pack cells.

The flow channel design is infinitely flexible and once the design is fixed the flow path is CNC machined into high carbon steel to form a stamping tool.

The tool can then produce high volumes of the flow path in Aluminium sheet by stamping, the typical thickness of this sheet is between 1 and 2 mm.

This process is very reliable and repeatable and suitable for high volume production.

This flow channel sheet is bonded to a flat sheet of aluminium, typically 2mm thick. This bond can be by structural epoxy or more usually by brazing. The flat sheet gives an excellent surface flatness and the flow path is accurate in its position to any through mounting holes. Overall thickness of the plate can be as thin as 5mm saving valuable space and weight.

Columbia-Staver have developed prototyping techniques that allow small volumes of cold plates to be manufactured prior to the production of the stamping tool.

 

 

The flow path can be optimised to achieve the desired thermal performance.

 

 

 

 

Multi-Layer Cold Plate
Columbia-Staver have developed the epoxy bonded multilayer cold plate.
This technology is ideal for prototypes and small production runs as no tooling investment is required.
The middle layer forms the flow path and can be customised so that the cold plate can mimic:

• Bubble plates
• Friction stir welded plates
• Serpentine plates
• Parallel flow extruded plates

 

Finished Cold plate with the three layers Epoxy bonded together and connector blocks fitted with “O” ring sealing

 

 

Image of Cold Plate with the upper layer made transparent. This shows the flow path, in this case designed to perform like a Bubble Plate

 

 

 

Exploded image showing the three individual layers, connector blocks and fixing screws

 

 

 

Three plane Cold Plate