New range possibilities for electric trucking
Run on Less event suggests new way of thinking about e-trucks
Organisers of the Run on Less project, which has been collecting data from electric truck fleet operators going about day-to-day business, have revealed some early findings. And they illustrate just how much electrification could alter the status quo of the trucking industry.
Early headlines from the project included one of the Tesla Semi trucks operated by beverages heavyweight Pepsico covering 794 miles in a single day — the first example of real-world range data for the Tesla — but ultimately falling short of CEO Elon Musk’s bold claim that it could travel 500 miles on a single charge.
A full report from NACFE is expected in October after the full range of data from the run is collated. But, speaking this week, Mike Roeth of the North American Council for Freight Efficiency (NACFE) and Ari Kahn of the RMI thinktank spoke of their surprise at their findings across several areas.
The trucks in the run have surpassed expectations about charging speed in some cases, according to Kahn. Chargers of 750kw were used on the largest Class 8 trucks, but vehicles cannot always sustain the fast levels of charge allowed by their charger.
“In the early days of electric cars, the charge profile, the amount of fast charging a vehicle could take was pretty underwhelming,” Kahn explains. “They could sustain that speed and power level for just a little bit and then drop off.”
But looking at the data, he is “surprised looking at these trucks seeing how much fast charging they can take and for a reasonable time”.
“It shows us how quickly they can go from a 10-20pc state of charge to 70-80pc and get that truck rolling again,” says Roeth.
Furthermore, the run appears to be showing that charging up to the 70pc-80pc range, rather than needing to go higher, is sufficient for many of the trucks' freight patterns. At state of charge (SOC) levels above 80pc, charging typically slows down and periods spent charging only to gain the top 20pc-30pc SOC cease to be time-efficient. Charging to full capacity also risks long-term degradation to the battery .
Sustained charging speeds, as well as the viability of departing for legs of a journey on 70pc-80pc SOC, make it feasible for a truck to charge twice in a day within existing truck downtime — as four fleet operators in participating in the run have done, according to NACFE’s Roeth.
“If that truck can get out for a second run during the driver’s hours of service, it may not need to get up to 90 or 100pc,” Roeth says.
Range ≠ single charge
This leads the NACFE man to encourage the industry not necessarily to equate range with how far a truck can go on a single charge, although he admits that this “is a mindset that can get in pretty quick”. Mid-shift charging, with the speeds demonstrated in the run, is now so feasible and scalable, Roeth says, that the industry should separate its idea of range from its idea of battery capacity.
Indeed, Roeth points to the benefits of “opportunity charging” — when a truck can incrementally top up its state of charge level during journeys without stoppages which delay the route. The real metric of range, he says, is how far a truck can drive within a driver’s shift.
“If the driver takes an average break – 45 minutes is what they tend to do – it can turn that 30pc into a 70pc and get another 100 miles,” he says.
This is facilitated by the charge speeds demonstrated in the run, which makes short bursts of charging sufficient and efficient for completing return-to-base journeys. “Maybe that longer return-to-base is something that is probable, not just possible,” Roeth says.
New charging behaviours
NACFE also says its data confirms that overnight Level 2 charging is efficient and scalable for urban delivery depots. “Small depots are ready to go now,” says Roeth, pointing to UPS, Purolator, and Frito-Lay locations participating in the run. NACFE finds that Level 2 overnight charging is also viable for relatively large depots with up to 100 mid-size trucks.
The patterns observed during the run also suggest an optimal range for freight journeys which balance distance and the possibility of multi-charging, which allows drivers to return to the depot, charge the vehicle, and “jump into another truck and they are back hauling freight really quickly”, Roeth says.
“There is a sweet spot in this medium regional haul return-to-base – which might be within that 300 mile/shift number,” he says, concluding that large depots such as Pepsico’s in Sacramento, CA are “more possible than we thought”.
However, the early data, while encouraging, shows fewer conclusive findings about long-haul journeys. “I do not think we know enough yet to be that optimistic about the longer, disparate routes,” Roeth says.
Roeth also addresses the lack of precise data about the payload of the trucks involved. Its non-inclusion caught observers’ attention at the beginning of the run. The feats of range achieved by the Tesla Semi trucks under observation will therefore be strongly caveated until NACFE’s October report.
“It is hugely disappointing that we are not able to track payload on these trucks for every mile,” Roeth says, adding that “we cannot show the payload live for lots of reasons”.
Despite the lack of precise payload information, NACFE can confirm that the three Tesla trucks in the challenge are continually dropping off cargo and picking up other goods — leading to variable payloads which are difficult to track. However, “it is not ‘out heavy, back empty’,” Roeth assures, “they are pretty heavy most of the time.”