Lithium-ion (Li-ion) batteries are becoming a preferred power source for off-highway and ground support equipment as industries push toward cleaner, more efficient operations.
The first part of this series examined the broader shift away from internal combustion, along with the growing need for durable charging infrastructure in outdoor environments. In this part, we focus on the battery connectors themselves, exploring the critical features that support safety, reliability, and performance under real-world conditions.
From weatherproof sealing to thermal safeguards and signal capacity, this article outlines key considerations for engineers selecting connectors in demanding applications.
Why IP68 sealing is essential
Charging batteries outdoors on busy airport aprons, rather than simply refueling internal combustion engine (ICE) vehicles, presents unique challenges, as noted in Part I. The electric charging infrastructure must be durable enough to withstand harsh outdoor environments and last throughout the year, regardless of wind, rain, and snow. The material handling and construction markets are also increasingly eyeing outdoor charging as a solution to their indoor space constraints, resulting in similar durability needs.
For any outdoor electric application, engineers should select a battery charger with an IP weatherproof rating to ensure consistent, reliable, and safe charging performance. IP68 is the highest standard, indicating the charger is protected against dust and debris ingress, and water immersion deeper than one meter for over 30 minutes.
Figure 1. An IP68-rated battery connector with sealing features designed to prevent moisture and debris ingress during outdoor charging operations.
Sealed battery connectors with an appropriate IP rating are critical for outdoor charging environments. Without proper sealing, dust can accumulate on the contacts, reducing conductivity and slowing charging performance. Moisture ingress can cause corrosion, short circuits, overheating, or even complete system failure. These issues lead to increased maintenance and can significantly reduce the charger’s lifespan.
To mitigate these risks, battery connectors equipped with IP68-rated sealing kits are now available, specifically designed for outdoor charging. These kits may include features like transparent voltage covers, dual O-rings, and rubber grommets that work together to form a secure, weatherproof seal when the connector is mated. This level of protection is ideal for applications such as outdoor ground support, material handling, and construction equipment.
Thermal considerations
Sealing is only one part of the reliability equation. Another growing concern, particularly for lithium-ion fast charging, is thermal performance. Li-ion technology enables fast charging, but excessive or improper charging can lead to overheating and, in rare cases, thermal runaway. This phenomenon involves a chain reaction in which the battery heats rapidly and releases toxic gases, including hydrogen fluoride, carbon monoxide, and hydrogen cyanide.
Beyond the battery itself, aging battery terminals (or contacts) are also susceptible to heat-related stress. As the contacts wear or corrode over time, resistance may increase, contributing to overheating.
In response, off-highway equipment engineers can turn to battery chargers designed with advanced signaling capabilities. Signals are the physical auxiliary pins within a connector that are used to transfer data and monitor the battery and power system. Signals might be used to monitor battery lifespan, mating cycles, charge level, connection detection, internal temperature, and more.
Figure 2. Advanced battery connectors for industrial use may include features such as IP68 sealing kits, contact temperature sensing enablement, and up to ten signals.
Newer connectors that offer eight or ten auxiliary contacts (rather than the traditional four or six) offer engineers an edge when it comes to extra temperature monitoring capabilities.
Some connectors also offer accessories specifically designed to monitor battery contact temperatures. By using a negative temperature coefficient (NTC) sensor on the IBC, engineers can easily monitor the temperature of the contacts during power transfer.
The real-time data provides an additional layer of safety by enabling a proactive response to overheating issues and helping prevent thermal runaway events during fast charging.
More signaling is also important for autonomous equipment. The material handling industry is increasingly embracing autonomous forklifts equipped with advanced sensors and AI to navigate warehouses, rather than relying on a human driver, as seen with Amazon’s adoption in 2024.
To support autonomous equipment, battery connectors with numerous auxiliaries are essential because they provide additional signals to monitor and control technology-intensive systems.
Key connector features
In addition to IP weatherproof ratings, auxiliary signal capacity, and contact temperature sensing, several other key factors should guide battery connector selection in the off-highway equipment sector:
Figure 3. This compact high-voltage connector integrates both power and signal pathways, supporting advanced monitoring and control in electrified off-highway and industrial systems.
- Connection security: Connectors equipped with spring-loaded latching handles provide a more secure mechanical connection between the plug and receptacle. This design helps prevent accidental disconnection and enhances connection security, a crucial consideration in high-vibration environments such as construction, material handling, or airport ground support equipment (GSE) operations.
- Compliance with standards: Engineers should prioritize connectors that meet appropriate regional and international standards. For instance, DIN VDE 0623-589 sets the standard in Europe for connectors used in battery-powered industrial trucks. Other relevant standards for safety and market compliance in different parts of the world include RoHS, UL 1977, CSA 22.2, IEC 60529, and EN 1175:2020.
- Modular design: Battery connectors with a modular design provide benefits in convenience, assembly, and maintenance. Consider an industrial battery connector that features a modular contact cartridge that enables tool-less assembly, contact repair or replacement. A modular design can reduce maintenance time, minimize the need for spare parts in stock, and make servicing faster and more effective.
- Size considerations: Smaller electric applications, such as light towers, professional-grade tools, or utility carts, will not require the large battery connectors typically used for heavy-duty equipment. Engineers should adopt the right-fit battery connector for their needs.
Taken together, these design factors equip engineers to make informed connector choices in an evolving, electrified equipment landscape.
A Li-ion-powered future
As the off-highway sector continues to electrify, modern Li-ion equipment requires innovative battery connectors designed to meet the performance demands of the future. Innovations like IP68 sealing kits protect against moisture and dust intrusion in harsh outdoor environments, while contact temperature sensing adds a layer of safety for fast charging. Enhanced signaling will also become more pivotal as autonomous equipment necessitates increased monitoring and control.
By choosing the ideal connector for their application, off-highway equipment engineers can prepare for electrification advancements and meet the signaling and sealing demands of the future. These design decisions play a vital role in ensuring long-term reliability, safety, and efficiency as Li-ion systems become the industry standard.
