On 5th June, researchers from Cambridge instrumented an electric tractor unit, recently purchased by one of our industry partners, Welch’s Transport. We attached our ‘SRF Logger’ hardware – a high-resolution, in-service data logging system, developed by the Centre for Sustainable Road Freight (SRF) over the past 10 years. The SRF Logger is being fitted to all of the EVs and diesel or gas comparator vehicles in Project JOLT – the Joint Operators Logistics Trial. The data is being used for a variety of data analyses towards the project’s aim of unlocking the potential of electric road freight in the UK.
A few days after installing the hardware, we were reviewing the data accumulated in the database and were surprised to see what the vehicle had been doing over the previous weekend (7,8 June). We expected to see routine logistics journeys: ‘A to B’ on the highway, with breaks for charging at Welch’s depot, along with charging data automatically sent separately to our database by their depot-based fast charger. Instead, we saw the data shown in the charts below… The electric vehicle went drag racing at Santa Pod Raceway! See this video of the event.
We didn’t have our logger on the (2nd placed) diesel vehicle – because we didn’t know about the race beforehand. It was a well-kept secret! But if we had logged the diesel, we would have seen that the EV generated significantly higher torque than the diesel off the starting line, with correspondingly higher acceleration and speed… The top speeds of both vehicles were automatically limited to 90 km/h (like all heavy commercial vehicles in the UK). For the EV, this occurred after about 20s of acceleration, at 11:21:17 (see figure below). We wouldn’t have seen any difference in the two top speeds once the diesel also reached 90 km/h. The EV has much higher torque and power at low speeds, so the diesel didn’t have a chance, despite the EVs higher unloaded weight!
The SRF Logger was a winner too. It showed the benefit of high-resolution monitoring of heavy vehicles in-service – and that you can observe unexpected things if you are measuring at the right time with the right tools. From other data collected, we can also see that the driver floored the accelerator pedal for 26 secs, starting at 11:20:56; the electric vehicle automatically changed gears after 6.5 secs; the motor reached a top speed of 1900 rpm at 90% of maximum motor torque; and for a bonus, the ambient air pressure and temperature at the nearest weather station were 1003.0 hPa and 14.8 degC!
Thanks to Chris Welch and Jamie Sands at Welch’s Transport for all their support for Project JOLT and for allowing us to share this data. Thanks also to the team at Cambridge University who made this data collection possible. Profs Xiaoxiang Na and John Miles; Ridwan Farouki and James Howe; Chen Liu and Harry Durham.
