Driven: Tevva range-extender prototype (2016) truck review

Tevva hybrid


Over the years, we have had many attempts to look at green or alternative power solutions for the automotive industry, all with varying degrees of success. 

The commercial vehicle sector has been no different. At one end of the spectrum are the likes of the ill-fated brand Modec, with its radical approach to designing an all-electric truck from the chassis up, and at the other the large volume European truck manufacturers and independents offering myriad hybrid alternatives, none of which appear to have hit the spot.

For an electric commercial vehicle to achieve mainstream success it would have to completely satisfy key areas, including range issues, cost and battery life; and from talking to truck engineers and senior executives, it seems there is no silver bullet. 

Governments have probably the biggest role to play as, with one change in the law, they can create or destroy a particular solution – just look at the history of LPG fuel in this country.

With this in mind, Commercial Fleet was invited to road-test an interesting solution in the alternative fuel market.

To a casual observer, Tevva may seem to have come up with just another hybrid – powered by an electric motor with an internal combustion engine helping to extend the range. 

The basic structure of Tevva’s vehicle supports that casual observation – in a chassis built by China’s JAC, a 120kW (the equivalent of about 161hp) electric motor, a 66kW lithium-ion phosphate battery pack and a 1.6-litre Ford diesel extender replace a conventional diesel engine and gearbox. Diesel was chosen because most commercial vehicle operators are more familiar with it. The battery-only range is 100 miles and a 38-litre fuel tank adds about 370 miles via the diesel engine.

The truck’s suspension has the standard arrangement of leaf springs all round, but the brakes are assisted by a regenerative braking system.

Tevva claims that CO2 emissions are 80% less than those produced by a standard diesel 7.5-tonne truck, with NOx emissions more than 50% less than those generated by a Euro 6 model. 

However, to describe the truck as ‘just another hybrid’ would do it and the team at Tevva a complete disservice. 

Almost anyone can bolt a set of batteries to a diesel engine and create a hybrid. But this vehicle gets more interesting once it is matched to its patented ‘predictive range extender management system’ (PREMS).

The system analyses the route (including road type, altitude and location), battery state and local air quality, which is used to predict the vehicle’s energy consumption and optimise the use of the range extender, maximising battery usage and reducing fuel consumption and vehicle emissions.

When travelling to or between urban centres, typically on high-speed routes, the engine maintains the battery charge. When the vehicle enters an urban centre, where emissions are a concern, the system ensures the diesel engine is only used where absolutely necessary, or not at all. 

Tevva says the batteries can be completely recharged from a three-phase 32-amp mains supply in under three hours.

The chassis has a GVW of 7,500kg, so complete with the box body, the kerbweight including driver and a full 38-litre tank of fuel it weighs in at 4,727kg, allowing for a payload of about 2,700kg.

Climbing into the cab is easy, as it sits low on the chassis. Once you are sitting on the mechanically suspended driver’s seat you wouldn’t know you were in an electric truck until you try to start it. The start process involves switching the keys to the conventional starter motor engage position, but this time the key is then brought back a notch… and nothing happens – there is no sound. 

On the left-hand side of the dashboard are three coloured lights: red for reverse, yellow for neutral and green for forward. Selecting green engages the drive system and we are ready to move off. Once the conventional short handbrake lever was released and I had pressed down on the accelerator pedal (there are only two pedals) the truck moved off – silently.

I have driven quite a few electric/hybrid trucks, so the sensation of moving and silence isn’t new, but for those unaccustomed to it, it can be quite unnerving. 

Despite the fact that this is a prototype truck, whose cab resembles more of a test facility than a working environment, it still has a dual passenger seat, standard instrument panel and good all-round visibility due to its low cab height.

Once we get out on the road, I don’t think anything can prepare a truck driver for the difference in acceleration between an electric-based truck and a conventional diesel. The power/torque developed at the wheels is immense and comes without the normally associated engine noise. 

However, when the range extender kicks in, you know about it. It sounds as though somebody has climbed into
the back of the truck, plugged in a vacuum cleaner and decided to give the load area an early, and very thorough, spring clean.

Tevva business project manager, Richard Lidstone-Scott, emphasised that the demonstrator is a prototype and added that production models will feature more sound-deadening measures. 

Actually driving the truck is a doddle – it’s basically an automatic and if going forward is easy, as is stopping. The regenerative braking system helps deceleration without touching the service brakes (and the consequential saving on pads/shoes). 

The prototype truck uses the rev counter to indicate power input vs output – the needle is in the 12 o’clock position when in balance, moving to the left when the regenerative brakes are used and right as power is used.

The ride in the cab was a little bouncy at times, but our test truck didn’t have a payload in the back, so was similar to what you would experience in a conventional truck. 

However,  one would have thought the placing of two heavy battery packs along either side of the frame should have given a slightly better ride experience. 

Perhaps if the batteries were placed a little further back this would improve. 

With a projected likely price tag of from £40,000 to £60,000, a truck like this does not come cheap. Against this hefty initial outlay however has to be weighed total cost of ownership savings of up to 27% over five to six years compared with a standard diesel 7.5-tonner, Tevva contends. 

That does not take into account any congestion charge savings and government grants towards the truck’s acquisition that might be on offer at the time of purchase. The Department for Transport and the Department of Energy and Climate Change have helped fund the prototype project.

“If we sell the vehicle as a Tevva using a JAC platform then we’ll probably be able to get it approved and into production in three to four years’ time,” Lidstone-Scott says. 

“A retrofit package suitable for other trucks will hopefully be available on a commercial basis within the next two to three years.”

Tevva’s equipment is also on trial with UPS in a Mercedes-Benz Vario in the London area. It could potentially be slotted into trucks grossing at up to 18 tonnes.

CO2 emissions and fuel consumption data correct at time of writing. The latest figures are available in the Fleet News fuel cost calculator and the company car tax calculator.