Adam Ricketts

Adam Ricketts

Head of Product @ Fleetsu

Talking Tesla – Conversations with the Tesla CAN

November 8, 2021

There are vehicle enthusiasts, there are gear-heads, and then there are people who actually talk to cars. Here at RandMcNally, we love decoding messages from a vehicle’s CAN-bus (internal data network) and seeing what it has to tell us. In the case of the Tesla Model 3, we can safely say that the Tesla CAN bus is the chattiest we have ever seen.

What is a CAN?

Modern vehicles are often said to be computers on wheels, but unlike your desktop PC with its single CPU, a car actually has multiple Electronic Control Units (ECUs) that need to communicate with one another. Each ECU is responsible for a system within your vehicle, whether it be the brakes, door locks, or components within the engine. The internal wiring of your vehicle connects them, and when they share information, they do so with encoded messages that vary with manufacturer and model.

This network is known as the Controller Area Network (CAN) – a good way to think of it is like a private chatroom where every message is shared with every participant.

Why Learn to Talk to the Tesla CAN?

At Rand McNally, we specialise in gathering automotive data for fleet managers who then in turn use it to make important business decisions about maintaining and using their vehicles. While external sensors and devices are useful, the gold standard is data straight from the CAN itself. It’s both more accurate and more plentiful.

In the case of a Tesla, the need for in-depth data is even greater as there is no external sensor that can get information about projected range, battery state of charge, or odometer.

What Does a Tesla Talk About?

As it turns out, the answer is anything and everything. After developing our own specialised hardware, taking the Model 3 on test runs around Perth, and cross referencing information with vehicle behaviour what emerged was a veritable torrent of data. From tyre pressure to battery temperature, from charge port LEDs to mirror position, the Tesla initially gave forth so much data that it overran the beefy internal memory on our hardware. However, after continued experimentation and refinement we have now been able to bring in over 300 parameters from the Tesla.

In particular we receive a lot of nuanced data around charging information, including some lifetime statistics. This information is particularly pertinent for Carbon Footprint accounting where it is important to understand whether the vehicle has managed to pay off its embodied carbon versus a comparable fossil fuelled model.

We are also able to get some great safety information, including information about passengers in specific seats, their seatbelt status, indicators, vehicle-detected road speed limits, and even whether the vehicle has detected that its been in an accident.

A Beautiful Conversation

Aside from specialising in extracting information from vehicle CAN’s, our other strength is providing an incredibly flexible toolbox for working with that data. Here are a few examples of business rules that could be built on the Tesla data we’ve just brought in:

Charging Cable Problems?

Create a workflow that listens for a charging cable that is present, but not secured. Afterwards wait for ten minutes before creating an alert. This prevents issues where a vehicle was thought to be charging all night when in reality the connector was loose.

Roadside Safety

Who needs to know when hazard lights are on? Send an SMS to a dispatch manager as soon as it happens. If there are false alarms, add a timer, or check against the speed limit of the road to determine if someone is on the side of a highway.

Range Alert

There’s no need to have someone glued to the Fleetmap looking at ranges, create proactive alerts when range drops below a key operational threshold. With a connection to a navigation API you can compare this against the distance to home-base and let the driver know they need to start heading back for a top-up.

Tyre Maintenance

Extend the life of your tyres and improve the efficiency of your vehicles by staying on top of tyre pressure. Monitor tyre pressure readings while parked and create scheduled reports for the maintenance manager to ensure that tyres stay in optimal condition.

There are dozens more possibilities with the data we already have, and easily that number again when the data is integrated with your ERP, CRM, or job scheduling software. Tesla is unique in the volume and quantity of data we receive, but all manufacturers hide a treasure trove of information within the vehicle CAN bus. If you’re only tracking location, you are leaving an ocean of data on the table. Reach out to us today and see what your vehicles have to say.

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