Driving Volvo’s heavy-metal electrics

theAllmajor truck manufacturers are racing to perfect their fossil-free drivelines, and Volvo Trucks is very much at the forefront. The Swedish manufacturer has recently released battery-electric versions of its FH, FM and FMX heavy trucks for operators keen to try their hand at ditching diesel for certain operations. This means Volvo’s entire range is now available to order in battery-electric form, with the new heavy-duty models joining electric versions of FL and FE in Europe, plus the VNR Electric for the North American market.

The three new heavies are aimed at regional distribution and construction markets and offer GCWs of up to 44 tonnes. FH Electric can be spec’d as tractor units in 4x2, 6x2 or 6x4 configuration; or as 4x2, 6x2, 6x4, 8x2 or 8x4 rigids. All axles are air suspended. FH cab options are low sleeper, sleeper, Globetrotter, and Globetrotter XL.

FM and FMX Electric are offered with the same axle configurations, while cab options are low day, day, low sleeper, sleeper, and Globetrotter. Volvo’s initial route to electrification has been to adapt its existing powertrains to work with new electric motors. Its solution for heavy trucks involves mounting electric motors directly onto a modified standard gearbox, which together form what Volvo is calling the Electric Drive Unit (EDU).

The lower-weight FL Electric uses one motor; FE Electric uses two; while FH, FM and FMX Electric use two or three electric motors directly attached to an I-Shift transmission. This latter combination affords the three heavy models a maximum power output of 490 kW (666 bhp) and a whopping 28,000 Nm of torque.

Batteries and service boxes are fitted along the side of the chassis. The battery assembly is built by Volvo and currently uses an array of Li-Ion Samsung cells. Each assembly offers 90 kWh of power and weighs around 500 kg – so buyers need to be careful to spec the right amount of power to meet their needs, as payload and operating range are directly impacted by each other.

Operators can choose to load the three electric heavies with two to six battery packs, with a maximum 540 kWh nominal capacity. As an illustration, an FH Electric 4x2 tractor unit and trailer fitted with six batteries and running at 30 tonnes GCW will have a range of up to 300 km (186 miles) on a full charge.

There are three power take-off (PTO) options: electric (40 kW), electro-mechanical (70 kW), and finally gearbox-mounted (150 kW) for extra-hungry equipment.

Battery-electric trucks essentially offer two ways of charging: AC up to 43 kW, which is good for overnight charging; or much faster DC charging of up to 250 kW. This is useful when driving two shifts, or if the driver needs to charge the vehicle during a break to add additional range.

With a 250 kW DC-charger, Volvo said it is possible to charge up to 80 per cent of the battery capacity in under 90 minutes. The final 20 per cent is slowed to a ‘trickle charge’ to preserve the cells. But in reality, we’re told, drivers are more likely to run the truck between the 20-80 per cent charge range so top-ups are fast, rather than hang around waiting for the trickle charge to complete.

Driving the FM Electric

We were recently given the opportunity to try out two of Volvo’s latest electric heavies, and the first truck we selected was an FM Electric tractor unit. Climbing into the familiar and comfortable FM cab, we were surprised to find the truck already switched on and ready to go. The lack of engine noise is the first thing that hits you with an electric vehicle; but sure enough, a touch of the pedal and we were off.

Even loaded to 33 tonnes, the truck aims to start in the highest possible gear (usually seventh) to save energy through reduced shifting. However, running cont.

through an adapted 12-speed I-Shift, lower gears are available if necessary – for example, when starting off on a steep incline or in situations that require additional torque and control.

Pulling away, we found the FM Electric gave that linear, smooth and powerful acceleration we’ve come to expect with BEVs. The motors deliver loads of low-down torque and making for a very positive drive. Once we’d made it out of the test site and onto the open road, the I-Shift ’box switched straight up to 9th and then 12th as soon as possible. The changes are as noticeable as a normal shift on a conventional ICE driveline; but with far fewer shifts overall, the drive felt super-smooth.

Once we’d acclimatised to the torquey engine, we could settle in for a relaxed tour of the immediate countryside. We didn’t encounter many hills so couldn’t get much of a feel of how the truck performs under heavy load, but performance at junctions, roundabouts etc was very sprightly. After half an hour, we pulled into a fuel station to swap over for our next ride.

FMX Electric

Next up was an FMX Electric rigid. Repeating the same route in reverse, this time we were focused on driving the BEV ‘properly’ – ie, not like a diesel – and this mostly involves a change in braking behaviour. Volvo’s electric trucks have a tweaked engine brake with automatic mode, and the strategy the driver needs to employ is almost backwards to that used on a conventional driveline. Instead of leaving the engine brake off and only flicking the stalk when you need to slow down, we were advised the most energy-efficient way to use it on the electric truck is to leave it in auto mode for the duration of the drive. This way, the driver knows that whenever they lift off the power, the truck slows using the engine brake and captures/ regenerates the maximum amount of energy back into the cells. Effectively this means you can drive the vehicle using just one pedal, with service brakes called on only rarely.

Driving behaviour is one of the biggest factors that influences power drain when operating BEVs. Others are weather conditions, tyres, topography, and load. According to Volvo, drivers have the potential to reduce energy demand by up to 20 per cent if they use the vehicle correctly – so proper driver training and coaching is going to be very important.

Though the technology is still in relative infancy, we continue to be impressed by the drivability of electric trucks. Volvo’s FM and FMX versions give a genuinely positive driving experience that we’re sure will win over sceptical drivers once they actually get behind the wheel and try it out.

The wrinkles, of course, are range and payload. Cell technology is getting better and the next generation of batteries will offer higher energy densities, which means hauliers will need to spec fewer battery packs to meet their required operating range – therefore reducing the truck’s payload penalty.

The concept of regular charging needs to be fully understood by the operator and built into the vehicle’s daily working schedule. Charging during statutory tachograph breaks will become particularly important – and this will require the UK’s network of charging points to be up to the job.

Until then, BEV operators will need to carefully plan work cycles and spec their trucks correctly for return-to-base activities. Thankfully, Volvo – and indeed the other major manufacturers – offer detailed consultations on this ahead of purchase to ensure demands can be adequately met.