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Understanding connectors for light EV applications – part 1

Electric 2Ws and 3Ws rely on complex electrical systems to function properly. Among the crucial components in these systems are connectors. This article by Dominic David (Director, Engineering at Chogori Connectors) discusses the basic parameters related to the selection of connectors for light electric vehicle applications.

What is the role of connectors in an electric vehicle?

Connectors are electromechanical devices used to join electrical conductors and create an electrical circuit. They come in a variety of shapes and sizes and play a vital role in ensuring that power flows safely and reliably throughout the vehicle.

What factors should one consider while selecting connectors for their EV application?

Several key factors must be considered when selecting connectors for a vehicle.

Current carrying capacity – One of the most important is the connector’s current carrying capacity. This refers to the maximum electrical current the connector can safely transmit without overheating or failing. The current carrying capacity of a connector depends on several factors, including the size of the connector’s contact pins. For example, a 3.6mm diameter of Chogori’s high-performance NEWSOK contact can carry up to 70A, while a 6.0mm pin can carry up to 120A. It is critical to select a connector with a current carrying capacity that matches the requirements of the system it is being used in.

Ability to withstand vibration – For electric 2Ws and 3Ws, their ability to withstand vibration is paramount. In the vehicle, connectors are exposed to constant vibrations that can degrade their performance over time. Fretting, corrosion, wear, and relaxation of contact forces are common issues that can increase the contact resistance of the contacts and reduce their performance and reliability. It is, therefore, important to select connectors that are designed to withstand these types of environmental stressors.

Temperature performance – Thermal expansion affects the flow of electrons when a conductor heats up, increasing the conductor resistance and reducing the efficiency of the system. It is important to select connectors that are designed to withstand high temperatures and maintain their performance over time.

Waterproofing – Electric vehicles are often operated outdoors and are therefore exposed to moisture, which can pass through the conductors and lower their insulation resistance and cause corrosion over time. A good waterproof connector can prevent water from entering the system and ensure that it operates reliably over its lifespan. The IPX7 waterproof rating, for example, means that a connector can withstand submersion under one meter of water for 30 minutes without any water intrusion.

User experience – User ease of use is also an important consideration when selecting connectors. Connectors must be accessible and easy to use, even for a wide range of users with varying levels of experience. They must be able to withstand a large number of mating cycles without failing. A good test plan, such as the SAE/USCAR37 test matrix, can help ensure that connectors are reliable and meet the requirements of the system and real usage scenarios.

Select the right type of connector suitable for the target application – Different types of connectors are used for battery charging and discharging, and is vital to choose the right one for each application.

For example, Large 2+1+5Pin connectors are used for battery discharging, while Middle 3Pin connectors are used for battery charging and onboard charging. Swappable batteries and charging stations require connectors designed for multiple insertions, easy locking and unlocking, and resistance to inappropriate usage scenarios.

On the other hand, onboard charging and removable battery scenarios require connectors that offer degrees of protection against solid foreign objects and water, an audible click when locking is engaged, and resistance to on-load vibration.

In conclusion, selecting the right connectors ensure the reliable operation of your electric vehicle. Choose connectors that are made of high-quality materials, are durable and equipped with necessary safety features to minimize the risk of charging failure and interruptions to vehicle operations.

The author can be reached at dominic@chogori.com.cn.

Click here for a deep dive into EV connector technology.

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