Navigating the Challenges of Automotive IoT Devices: Understanding ISO 16750 Standards

It’s often not obvious until you start getting into the details, but IoT devices are held to higher standards than consumer electronics. This includes radio performance (IoT devices need to have 4 times the performance of a typical iPhone), battery life, performance over temperature, performance vs age (why does your wifi AP start to suck after 3 years or so?), dust and liquid ingress, chemical and solvent resistance, shock, vibration, and electrical protection.

The exact requirements vary with the specific use-cases. We work on a lot of mobile devices for use in a variety of vehicle applications. This can include off-road heavy construction equipment and heavy or medium fleet trucks all the way down to fleets of motorcycles or scooters.

For on or off-road vehicles, one of the most common reference standards is ISO 16750. This defines electrical and mechanical robustness for electronic devices to be used in vehicles. The standards apply to on-road passenger cars and trucks, as well as semis, motorcycles, power sports vehicles, snowmobiles, and off-road construction and agricultural vehicles.

About ISO 16750

ISO 16750 is a series of international standards that relate to conditions and testing for electrical and electronic equipment in vehicles. These standards are developed with help from experts worldwide through the International Organization for Standardization in Geneva, Switzerland. The standards are well known and adhered to by various industries and basically define what a device needs to be able to survive in a vehicle application.

Five basic requirements are covered by ISO16750:

Using an IoT device for contract enforcement is applicable in many situations. Below are a few examples:
• General
• Electrical loads
• Mechanical loads
• Climatic loads
• Chemical loads

The section that is most relevant here is 16750-2 on electrical loads. This section alone contains 12 tests related to the robustness requirements. This includes testing for direct current supply voltage, overvoltage, superimposed alternating voltage, slow decrease and increase of supply voltage, reversed voltage, ground reference and supply offset, open circuit tests, short circuit protection, withstand voltage, insulation resistance, and electromagnetic compatibility. Each section describes the requirement, why it exists, and how to test for it.

Why these standards are important

The environment inside automotive vehicles is harsh – both physically and electrically. There are electrical transient issues that can occur when you are installing or uninstalling something, or when you are otherwise interacting with the vehicle. This includes when the vehicle is jump-starting another vehicle, which is when something called load dump can occur.

The rest of the tests really aren’t too hard to pass once you understand how to design your circuits. Load dump involves a fair amount of energy dissipation, so it can be a bit more tricky to deal with, especially when your device needs to be very low current consumption, operate at lower voltages or in other special cases.

Load dump refers to a situation when the generator of an electrical current is abruptly disconnected. In automotive situations, this is most common when you jump start a vehicle. You attach the running car to the stalled car, your electrical system starts supplying power to the stalled car and its dead battery, drawing a lot of current. The stalled car gets started, or worse, doesn’t get started, and you disconnect the running vehicle from the stalled vehicle. The moment you break that connection, the large amount of current from the running vehicle now has nowhere to go and, for a short time, the voltage from the alternator in the running vehicle spikes. This can be well over 100 volts when it happens. The stalled vehicles are fine with these spikes, but rescue vehicles that have any aftermarket electronics not designed with this situation in mind can blow out and be completely destroyed.

For things that live in the car, such as entertainment centers, emissions testers, vehicle trackers, and other electronic devices, load dump can result in costly damage. Load dump also has the potential to seriously damage the vehicle itself though pretty much everything in a modern car. The OEM is specifically designed to handle this because it’s designed to meet the ISO 16750 requirements, which include a test for this.

How can problems be avoided?

If you want your device to survive in a vehicular environment, it needs to be ISO 16750 compliant. The whole purpose of ISO 16750 is to help to avoid issues associated with load dump and other environmental factors.

At F3, we design for ISO 16750 (and other standards in ag, aero, medical and other markets) for clients all the time. We know how to build devices and test them to ensure devices meet the required standards. Trust our experienced team to get it done right the first time.