As of early September, the Battery Electric Truck Trial (BETT) vehicles, used by nine different Midlands and northern England-based public sector operators, had travelled 260,000km over 19,000 journeys. All, DAF LF Electrics, were fitted with the largest 282kWh battery pack (250kWh) for 280km nominal range; payloads varied from 7.3-9.3t. Operators were supplied with a total of 14 chargers, either a 22kW AC fast charger for overnight charging or a 150kW DC rapid charger for shorter periods.
Surveys and anecdotes from one operator suggest that the vehicles, all 19-tonne DAFs with Gray & Adams lightweight bodies and Dhollandia tail-lifts, generally performed well, and particularly to the satisfaction of drivers, despite negative initial preconceptions.
If anything, they may have been over-specified for their duty cycles, the study found. 80% of the time they were plugged in, the state of charge was greater than 50%. That suggests to the researchers that there was more than enough range for the chosen duty. Also, users typically charged the vehicle to full.
Of the 21,000 hours of the trial, there were 8,600 operating hours, 5,200 fast-charging hours and 1,800 rapid-charging hours.
Journeys were classified into urban, rural and motorway travel. Urban journeys had the greatest level of regeneration from braking, but were found to be the least efficient. On the other hand, motorways had the least amount of regeneration, but suffered the most from fighting air resistance. Rural journeys had the highest efficiencies, of about 1.2km/kWh. The overall fleet average was 1.08km/kWh, but that headline figure covers lots of complexity and variation in payload, weather and ancillary loads.
Eight transported refrigerated loads using a Carrier fridge. Fridge trucks were found to be slightly less efficient overall. The most important factor in the difference in efficiency between fridges and ambient trucks was the greater weight of the vehicles, typically 2t unladen, compared to ambient trucks. Meanwhile, motorway journeys were found to be the least affected by the increased weights because of the continuous nature of the travel. When the trucks were more than half full (above 14.8t gvw), motorway travel on average was slightly more efficient than rural travel at just over 1.1km/kWh, whereas urban was much worse (under 0.8km/kWh).
A surprise found in the data in the winter months was the power drain due to the cab heater: in early 2023, as the temperature dropped below 10°C on average, drain exceeded fridge baseload and fridge consumption together, accounting for more than 5% of total energy consumption.
Vehicle ranges varied, up to a maximum of 30,000-40,000km over the trial. Some vehicles had very low mileage for operational reasons.
CHARGING
DAF’s EV and sustainability manager Adam Bennett stated private charging infrastructure at customer sites will be needed to be cost-competitive with ICE.
The trial revealed a number of lessons about setting up charging infrastructure. First, all of the decision-makers should get involved positioning charging from the start. The purchaser might choose a corner on the site without understanding all of the implications of that position on operations. Site restrictions and one-way systems might complicate access. And there were occasions where the spot chosen was a long way from the connection or the power supply.
Bennett suggests that operators consider ways to be at least partly self-sufficient in terms of electricity; that could mean commercialising access to charging stations at downtimes, or consider installing photovoltaic solar panels to help reduce draw from the grid, and hence the electricity bill.
Operators also need to consider what happens after the chargers are installed. How do you maintain the infrastructure? What is the software platform, how can service providers have remote access? Is the site provided with a spare charger, in case of breakage or fault? What about a service level agreement for maintenance?
Lack of provision in the maintenance SLA posed a big headache for Prohire, provider of trucks for NHS Supply Chain, reported Michelle Miles, head of its sustainable division Progreen. When a couple of its 150kW rapid chargers stopped working, and couldn’t be repaired remotely, it requested an urgent support call. But the SLA with the contractor didn’t class that fault as urgent, so a fortnight passed before a mobile technician was available to fix them.
Reflecting on that situation, she says: “If you get the infrastructure right, you can fuel them. But if you don’t choose right, it’s hard to maintain buy-in when things go wrong – people give up.”
On the other hand, vehicle uptime was good, she said, as expected – there are fewer things to go wrong on an EV, as the EV drivetrain usually does away with the engine and gearbox which contain so many moving parts. (In fact, DAF has designed the EV models so auxiliaries and powertrain controls are housed in an electric drive module the same size, shape and location as the engine, for ease of fitment on the line in Leyland, Lancashire, reports Chris Griffiths, Leyland Trucks’ chief engineer.)
The DAF trucks themselves were generally reliable. Any delays that occurred during servicing were not due to lack of training, but the lack of technicians; sometimes the operator had to wait for a qualified technician. “Infrastructure is not just the charger, but also the dealer network,” she observed.
In a nutshell, she said it was a successful trial, even if not everything was perfect. “We found that we had amazing collaboration benefits in working with suppliers. We can’t do it
on our own.”
PROGRAMME DETAILS
Cenex was responsible for organising the trial, gathered data from telematics boxes fitted on the trucks, as well as performing interviews with participants. It analysed the data and produced periodic and will produce final reports, covering factors such as financial total cost of ownership and total lifecycle carbon emissions. In addition to five quarterly reports, four ‘deep dive’ reports have already been published, analysing drive cycles, driver behaviour, charging efficiency and ancillaries and payload. All are available via www.tinyurl.com/36bt4dvb.
The trial was funded by government, through Innovate UK, plus the Department for Transport. In particular government spent, through the Small Business Research Initiative, £10m to procure the vehicles and chargers.
BETT will be followed by two much bigger trials of BEVs and hydrogen fuel cell vehicles, over a longer trial period (five years) and involving more than 10 times as many vehicles (200-400, according to Isabella Panovic, programme manager of Zerft) and many OEMS. She says that one trial has already started, but details had not been released at the time of writing.