Designing a lithium battery pack with high current capacity requires all the electrical connections to be well executed. While the cells may perform well electrically, one can’t ignore the importance of a good busbar connection.
One may think that while the resistance of one busbar is insignificant, the same doesn’t apply to the battery pack consisting of several busbars. The increase of resistance will affect voltage drop, heating, and energy losses.
The importance of electrical contact resistance in lithium battery busbars is high not only in designs of the battery pack but also in the manufacture of this item.
For companies producing prismatic lithium battery cells, the busbar is not only a piece of metal connecting terminals. The material, dimensions, surface state, contact surface, holes, inclines, and latitude determine the quality of the end connection in many aspects.
Electrical contact resistance refers to the resistance present at the interface between two conductive materials when the electric current flows from one material to another.
As far as lithium batteries are concerned, electrical resistance can happen where the busbar meets the battery terminal or where the busbar meets other conductive connections.
Despite both materials being highly conductive, the actual contact between the two materials is uneven. Surface roughness, contamination, oxidation, contact pressure, or quality of the mating surfaces can affect resistance.
In other words, it is vital to monitor those parameters in case of high-current applications of batteries.
A busbar serves as a conduit of electricity for the batteries and electrical components. The busbar should have low resistance.
When the contact resistance increases, several issues arise.
1. Excess Heat Generation
The equation for electrical loss can be expressed as
P = I²R
Where P = power loss, I = current, and R = resistance.
The important aspect is that current is squared, and at high levels of current, a small increase in resistance can cause quite a lot of heat.
2. Voltage Drop
Resistance causes voltage drop:
V = IR
A connection with high resistance will produce greater voltage drop at higher values of currents. The battery could produce electrical power less efficiently.
3. Reduced Efficiency
All connections produce electrical losses, and according to the quality of the connections, a poor connection could cause unnecessary losses in the battery system.
4. Thermal Discrepancy
A poorly connected device could generate a higher temperature level than the surroundings. Furthermore, thermal gradients could create unwanted consequences.
Contact resistance is not solely dependent on the busbar material. In fact, many of these elements play a vital role:
Busbar Material
Both copper and aluminum are conductive materials, yet they exhibit different mechanical and electrical characteristics.
Copper is an excellent conductor, making copper bars an appropriate option in applications that need compact current connections.
Aluminum busbars are preferred for their high conductivity, lightweight, and acceptable price.
Selecting the appropriate material depends on the construction details, current level, and wiring method.
Surface Condition
The surface has to be adequate for connection purposes; any impurities, such as oxidation or dirt, burrs, and other surface imperfections, will affect the size of contact and affect the resistance.
This is one reason why it’s important to have precision cutting, deburring, and proper surface finishing processes during busbar manufacturing.
Contact Area
A well-designed connection must provide sufficient contact area for the transfer of current.
An insufficient contact area of the busbar can result in excessive electrical and thermal stresses.
It is important to take into account the terminal connection’s configuration and parameters while designing rather than doing this afterwards.
Fastening and Contact Pressure
In the case of connections with mechanical fastening, contact pressure is a very important parameter.
If contact pressure is too low, the connection may become unstable, if it is too high, there may occur some mechanical problems.
The connection must be designed in accordance with the battery manufacturer’s requirements and the chosen technique.
Manufacturing Accuracy
A busbar can have the right thickness and material but the wrong holes, bends, lengths, or terminal features, which will cause problems.
Poor dimensional accuracy will lead to a lack of alignment and improper assembly conditions.
For a battery maker, uniformity is as crucial as the substance itself.
A busbar of the right quality must be manufactured in accordance with the approved drawings and the specification requirements.
At Adinath Enterprises, the busbar manufacturing approach involves:
Reviewing the drawings and requirements
Choosing materials as per applications
Cutting precisely
Punching and making holes
Bending and shaping material as required
Drilling and tapping where necessary
Chamfering and deburring
Finishing the surface
Checking the sizes
Quality checking before dispatch
This is how it becomes possible to produce busbars that would meet the mechanical and electrical designs.
This is particularly important for the prismatic lithium batteries since the busbar should repeat the geometry of the cells’ terminals and conform to the battery pack design.
A busbar that is well-designed and produced has many benefits, such as
Uniform electrical connections
Better tolerance
Less chance of making mistakes during installation
Stable paths for flow of current
Better fit in small batteries
Uniform manufacturing of battery packs
Easier work with production automation
Improved overall manufacturing process
However, a busbar on its own is not sufficient the final performance of the system highly depends on battery terminals, the method applied for joining the elements, fastening conditions, the packs’ configuration, etc.
A few defects are not evident until the battery assembly is in progress.
Out-of-Place Hole
A tiny mistake in dimensions may complicate the installation of the busbar and cause the contact area to diminish.
Sharp Edges and Burrs
Rough edges may interfere with assembly and lead to mechanical or insulation and heat-related troubles.
Incorrect Cross-section Values
Altering the thickness of the busbar influences the capacity of current to pass through, strength, weight, and general forms of the battery.
Bad Surface Finish
The given surface condition must be suitable for the connection type and surrounding environment.
Ignoring the True Battery Arrangement
The busbar must not be designed strictly from calculations. The busbar must conform to the battery cell position and arrangements too.
Considering All Battery Busbars as Uniform
The prismatic batteries may have various terminal locations, sizes, spacings, or requirements of connection. Busbars with standard dimensions may not satisfy the needs of the specific design.
Specific design and manufacturing techniques can help.
Utilize the drawing from the battery maker to create the busbar in line with its terminal design and mechanical characteristics.
Select the component material based on the application requirements rather than selecting copper or aluminum as common materials.
Pay attention to the contact area. Quality of the surface, area of the contact surface, and fastening methods should be properly considered.
Be careful with the dimensions of the product during the production process. Compare the dimensions with the drawing to know the hole locations, its thickness, angles of bending, and the length.
Do not forget about finishing. Deburring and proper surface treatment can ensure uniform performance of the component.
Inspect before shipping the product to make sure that a dimensional issue is eliminated much earlier than at the assembly stage.
Adinath Enterprises specializes in manufacturing custom busbars of copper and aluminum for electrical applications in industries as well as batteries.
The company produces busbars based on customers’ drawings and specifications for prismatic lithium battery applications. Different manufacturing procedures are used, such as cutting, punching, folding, drilling, tapping, chamfering, and finishing.
The mission is clear produce the busbar that suits the design requirements perfectly.
Adinath Enterprises manufactures busbars for various uses, including EV batteries, energy storage systems, solar power batteries, and other battery systems.
The company can customize tin-coated copper busbars as well as aluminum busbars depending on the need for the applications.
Using this kind of methodology may help make the sourcing of products more effective for battery manufacturers since the busbar is produced specifically for the requirements of the battery pack.
What does contact resistance mean in the context of lithium battery busbars?
Contact resistance is the term used for the electrical resistance occurring when a busbar and battery terminal connect. It plays an important role in the voltage drop and heat produced during high current transmission.
Does it matter what the busbar is made of in terms of contact resistance?
Yes. Copper and aluminum differ in their electrical, mechanical, and surface properties. Contact resistance also depends on how the contact surface is made, the pressure used, the size of the contact spot, etc.
Can copper busbars be used in lithium battery packs?
Yes. Copper busbars are very popular for battery systems due to their outstanding electrical conductivity and efficiency however, the choice of material is determined by the specific design of the battery equipment.
Why is aluminum used for busbars in EV batteries?
Aluminum is lighter than copper, thus making it a viable option for many applications.
Can busbar manufacturing influence battery pack efficiency?
Definitely. Incorrect manufacturing dimensions, poor surface treatment, burrs, or holes that do not fit the original specifications can make the busbar not fit properly or poorly connect with it. Thus, a uniform method of production is key to eliminating the problems with mechanical and electrical connections.
Is it necessary to customize battery busbars?
In most cases, customization is recommended for prismatic battery packs, as cell dimensions, terminal locations, spacing, current requisites, and installation space vary from design to design.
What are the main requirements for a busbar manufacturer?
In a perfect situation, the approved drawing should be supplied with material, thickness, dimensions, distance between the holes, bend specification, surface-treatment requirements, quantity of busbars needed, and other requirements essential for their use.
Electrical contact resistance may be a very low number, but one should not underestimate its influence in lithium battery systems where high current is used.
The correct choice of materials, suitable design of contacts, right size, proper surface treatment, and consistency in manufacture should all contribute to better busbar connections.
If battery manufacturers work with prismatic lithium batteries, choosing a manufacturer of busbars who knows how to produce using drawings can help to solve fitment and consistency issues during assembly.
Is it the case that when developing or searching for custom busbars made of copper or aluminum for your lithium battery packs? Adinath Enterprises can review your drawing and requirements for manufacturing and make a busbar according to your specifications.
For any query, please call us, email us or fill the form and wewill contact you shortly.
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