Comment: Fossil-fuel thinking12 October 2023

How much fuel is enough? In the real world, most of us fill up completely every time we visit a forecourt. And data from the Battery Electric Truck Trial (BETT) presented at the Cenex-LCV show reveal that triallists using EVs did the same thing. Almost all charges were to 100%, and 80% of the time the 19t rigids had a state of charge greater than 50%. In other words, trial data suggests that users didn’t need the 282kWh batteries (providing up to 175mi range) fitted. More from that trial next month.

What we have here is a case of fossil-fuel thinking, which poses problems for running EVs. Even assuming that you can get out all of the electricity that you put in, not only are EV batteries very expensive to purchase, they are heavy, too, which imposes its own ongoing cost, at a rate of about 7kg/kWh, based on the rate of IVECO’s eBS 37 bus and LCV battery pack at the show. On an EV, fitting battery capacity that isn’t used is not like brimming the tank on a short run. It’s more like fitting a second entire engine.

Let’s rephrase the initial question: what’s the minimum amount of fuel that a vehicle needs to carry? Ideally, only enough to get to the destination, plus a little extra to cover contingencies. Ideally, a BEV would flit from one charging point to the next, carrying as little weight as possible to maximise efficiency, and then stopping to charge, just long enough to get to the next stop. That duty cycle has a name, opportunity charging, and an application: urban bus routes. Many such systems have been built in Europe (and Birmingham airport).

Such a duty cycle also fits with European drivers’ hours legislation, which requires drivers to stop periodically anyway. Why not do some charging at the same time, asks Phil Moon at DAF, who helped pilot a DAF LF Electric in the third annual EV Rally around the UK and Ireland in July. The team attempted to do that using public infrastructure, and mostly succeeded.

In the real world, it’s lack of infrastructure driving range anxiety: better fill up now, because you don’t know where you’ll be able to next time. But is that really true? Surely at least some percentage of every depot’s daily runs are predictable, back-to-base or below 175mi. That was certainly proven for operators in the BETT project. Have ICE fleet operators ever actually tried to answer that question?

Will Dalrymple

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