The reliability and performance of a battery management system (BMS) aren’t just based on its electrical components. Physical components contribute to several aspects of the BMS, including electrical safety, structural integrity, and long-term reliability. They also protect the internal components, making sure they’re safe from external hazards.
In this article, we will dive into the various physical components in a BMS that can be made through plastic injection molding technology.
Key BMS System Components Made by Injection Molding
Connector Housings
Connector housings in BMS systems are responsible for securing the female contact points from environmental factors like water, air, and dust. They come in low-profile and compact designs to easily fit on various setups with minimal space consumption. These components are typically built using high-quality plastic materials to improve signal integrity and prevent overheating even in strenuous conditions.
Battery Trays
Acting as main containers for battery management systems, battery trays help keep the other components together in a single package. These trays include several racks to place the different parts of the BMS, providing a safe and organized space. As such, the materials used in creating these plastic injection molded parts are carefully selected to have improved durability and resilience.
Gaskets
Usually made from injection molded elastomer, BMS gaskets are used to seal the battery pack, preventing environmental contaminants from entering and potentially damaging the system. They also inhibit internal fluids from leaking out of the system while providing electrical insulation, thermal management, and vibration absorption. Materials used in making gaskets must have high chemical resistance while having enough flexibility to create tight seals.
HVIL (High Voltage Interlock Loop) Housings
Housings for High Voltage Interlock Loops or HVILs serve two purposes: to ensure a stable connection within the circuit and to protect users from contact with high levels of electricity. This plastic injection molded piece forms part of the HVIL circuit and automatically de-energizes when the lock is broken. The design of HVIL housings is fully customizable, typically including a touch-resistant surface and the capability to accommodate various connections.
Insulators
Insulators play key roles in maintaining the safety and optimal performance of battery management systems. From preventing electrical leaks to helping reduce battery fires, proper insulation will keep the BMS running at optimal levels. As such, plastic injection molded insulators require materials that can resist contamination and stress for long periods.
BMS Sampling Board Mountings
Used to install circuit boards and other components, sampling board mountings ensure stability and safety within the entire battery management system. Additionally, these mountings protect the sampling board from any potential damage while maintaining a stable connection when in use. They come in various types and installation options, from standard screw homes and snap fastening to utilizing adhesives and DIN rail mounting.
Busbar Tray
Busbar trays are enclosures that contain metallic conductors, also called busbars, used for high-capacity current flow and balanced power distribution throughout the BMS. This helps make the BMS more organized and compact while improving system performance and reducing short-circuiting that can lead to overheating.
Cell Carrier
Cell carriers act as the local interface for individual battery cells in a battery management system, typically taking the form of a printed circuit board or a module. It’s responsible for monitoring the voltage of each cell, detecting and regulating temperature changes, and data acquisition, to name a few. The main module or bracket is made using injection molded plastic parts, adding electrical insulation and durability to the carrier.
Bulkhead Connector Housing
Designed to support bulkhead connectors on a BMS, bulkhead housing connectors help facilitate the secure and organized connection of various components while ensuring the panel’s integrity. The injection molded plastic housings typically feature a threaded barrel and a fastening nut to create a connection that’s resilient to vibrations and shocks common on industrial and EV setups.
Voltage Connector Housing
Designed as an enclosure, voltage connector housings are responsible for protecting the voltage wiring installed in a battery management system from dust, moisture, and vibration. It also helps in keeping the wires safe and organized, supporting hot plug sequencing requirements, and ensuring proper separation of high-voltage and low-voltage control circuits.
Optical Connector Housing
This protective enclosure acts as the outer body of fiber optic connectors in a battery management system, allowing the ferrule to safely connect to an external adaptor or port. The design of optical connector housings typically features push-pull latches or screw threads to facilitate stable connections. As the housing is usually exposed to stress, the material used in making this plastic injection molded part must meet requirements for durability and environmental resistance.
SIB Busbar Tray
This tray component typically houses an SIB or Solid Insulated Busbar that helps facilitate proper electrical power distribution throughout the Battery management system. As the tray is constantly within proximity to electrical components, the material used in making them must have high electrical insulation capabilities to prevent disruptions in operation or electrical loss.
SDM Terminal Boot
The SDM terminal boot contains sensitive components that handle and manage software functions within the battery management system. The SDM terminal boot must not only be sturdy but also resistant to environmental factors like moisture, dust, or corrosion.
Common Requirements in Mold Design and Injection Molding
Now that we’ve identified the components in a battery management system that can be made using injection molding, let’s look at some basic requirements for successful part production. These factors will ensure that the injection molded components will have the proper qualities to improve the performance and service life of the BMS.
For Mold Design
Mold design is a crucial step in manufacturing plastic injection molded parts for a battery management system. During this step, it’s important to consider having tight tolerances and material shrinkage on the mold, especially for housings and connectors. Designers must account for uniform wall thickness as well to prevent warping or sinking as the plastic component cools.
As for the design itself, BMS component molds must include cooling systems to help release heat within the unit and reduce equipment cycle times. Moreover, the mold design must include draft angles, strategically placed gates, and proper air venting to make filling more efficient. These will also help release the plastic part after cooling without damage or defects.
Adding features for easier assembly and inserts will help elevate the overall mold design. Ribs and bosses on the parts will reduce stress on the components during assembly, leading to better structural integrity. There should also be enough room for metal inserts that will be added later on, and planning this during the design phase will ensure proper adhesion during the process.
For Material Selection
First on the list when selecting materials for plastic injection molded BMS components is its dielectric strength, which refers to its capability to withstand electric currents. This prevents the occurrence of electrical shorts within the system and guarantees high-voltage components are properly isolated.
Then there’s the flame retardancy and thermal resistance of the material, making sure they meet global standards for safety and use. Materials with great chemical resistance will also benefit the completed components, making them more resilient to moisture, chemicals, and other environmental factors.
Other considerations for materials include dimensional stability and mechanical strength, which will extend the service life and reliability of the BMS. Materials with high dimensional stability have tight tolerances and low shrinkage, which contribute to the parts fitting perfectly. Mechanical strength, on the other hand, relates to the toughness and impact resistance of the completed part.
For Injection Molding
As for the injection molding, brands must consider how their chosen plastic injection molded component manufacturers handle their production process. Particularly, they should have a good grasp on temperature control and regulation to ensure the proper flow of molten material to the mold. They should also practice highly calibrated injection speed and pressure to prevent overflowing or gaps within the mold cavity.
Quality control is also important, making sure the completed BMS components meet required local and international standards. Strict monitoring in every step of the process and utilizing modern control systems will guarantee consistency in every component completed, no matter the quantity or volume. Having specialized tools for specific materials will prevent damage or degradation, so a manufacturer that uses those is a plus.
Benefits of Choosing Injection Molding for BMS Components
With the wealth of advantages plastic injection molded BMS components have to offer, there’s little to stop brands from going with this option for their next project. But for those who are still on the fence, here’s what you get by choosing injection molding in making components for battery management systems.
Integration & Lightweighting
Compared to other materials, modern plastic has comparable durability to metal while being more lightweight. The plastic material for these injection molded parts can also be modified to include more features to improve its capabilities, like chemical resistance and electrical insulation. Moreover, custom injection molded parts can be customized to integrate with existing setups, allowing for easy expansion and configuration.
Cost-Effectiveness & Consistency
Another perk of choosing injection molding is the relative affordability of materials and manufacturing processes that it lends to BMS brands without compromising quality and durability. Large-volume production of plastic injection molded BMS components is also more cost-effective instead of purchasing in limited quantities.
Speaking of large-volume production, opting for this route ensures consistency in the quality of the completed components. Injection molding manufacturers like Fox Mold implement strict quality control to guarantee every batch meets international standards.
Design Freedom
With plastic injection molding, battery management system manufacturers have more freedom to configure the components as they see fit. Adding features like more exhaust vents and spaces for inserts will not only make assembly easier but also improve performance and longevity. Designers can also configure the BMS to be more compact yet still retain their features to accommodate their growing market.
Enhanced Reliability
Modern plastic injection molded parts have more resistance to environmental factors like dust, moisture, and ultraviolet rays, which are common causes of degradation in metal parts. Moreover, the plastic components can withstand vibration, electricity, and heat better than other materials. These factors make plastic BMS components more reliable and durable, extending their service life while boosting brand recognition.
Over-molding creates a seamless, watertight seal for superior protection, while integrating a durable cushion that dramatically boosts impact resistance and long-term reliability. Overmolding elevates BMS housings from simple plastic parts to robust, high-performance assemblies.
Frequently Asked Questions on Injection Molding for BMS Components
Metal Inserts – Insert Molding or Post-Assembly?
A common concern BMS manufacturers have regarding injection molding components is regarding metal inserts. Connector trays and busbar trays, for example, have metal parts inserted on them for optimal functionality. So, the question is, should the metal inserts be introduced through insert molding or during the post-assembly process?
As professional plastic injection molding component makers, we highly recommend utilizing the insert molding process for metal inserts on BMS components for better sealing and strength. Since the insert is placed while the plastic mold is forming, it adheres better to the plastic component. It is also for large-volume production, where automation can expedite the manufacturing process.
However, if the components or inserts have unique or complex shapes, placing the metal inserts post-assembly would be the better option. This process also works well for low-volume production, as it requires dedicated personnel to assemble the metal inserts with the components.
Case Experience:
We recently handled a project where the initial design the client provided for the BMS box had issues with grounding and sealing. The metal inserts were not secure on the box, causing them to detach over time, which leads to the grounding.
To address the concern, we went with the insert molding process that secured the metal inserts within the plastic component. This not only sealed the inserts in place, but it also addressed the grounding issue by holding the inserts snugly.
Are Tolerances on the Drawing Practical and Cost-Effective?
Another common question our designers get from clients is the practicality of adding tolerances during the drafting process. Specifically, there’s a concern as to whether tighter tolerances are cost-effective, especially for large-scale production.
Tolerances refer to the allowable limit for measurements to deviate during production without compromising its performance or capabilities. Typically defined during the drawing process, this gives the designers an idea of what the minimum and maximum limits are for an injection molded part.
Looser tolerances can be faster and more economical production-wise, but the output may widely vary dimension-wise. Conversely, tighter tolerances produce consistent part dimensions in exchange for requiring specific tools and a longer time allotment that can increase the price.
At Fox Mold, we meticulously review the initial design documents and client preferences for the injection molded part. Combined with our years of industry experience and manufacturing know-how, we recommend the most economical and achievable tolerances for the project without compromising quality and function.
How to Optimize Design for Better Molding?
Most clients want to have the best injection molded plastic parts for their products, be it for their battery management system or otherwise. Part of achieving this is by optimizing the design to ensure that the mold and the final component will be the best it can be. However, a big concern is how to optimize the design.
The design team at Fox Mold provides a DFM or Design for Manufacturing analysis during the drafting process, indicating potential flaws in the current project. These include wall thickness, draft angles, and rib designs, among others. We also provide a detailed list of recommendations to fix these issues, preventing defects from occurring and improving the overall output of the injection molded component.
Wrapping Up
Battery management systems include an assortment of parts, some of which are made through plastic injection molding. These components not only protect sensitive parts from damage or heating but also improve the performance and extend the service life of the BMS. Knowing what to look for when sourcing injection molded BMS components will help your products reach their potential and grow your business.
If you’re looking for a reliable partner to source your plastic BMS components, choose Fox Mold. We’re a professional injection molding manufacturer with years of experience and satisfied clients that can help meet your plastic BMS part needs. Book your free consultation today and see how we can take your ideas to another level.
