Is your next tow vehicle electric?

The battery-electric vehicle is not just the way of the future, it’s already here. But what about the EV as a tow vehicle -- are any of the various forms of electric vehicle a realistic alternative to the internal combustion vehicle?

What is an electric vehicle?

There are a few shades of EV, from the mild hybrid to fuel cell EV.

Hybrids have both an electric motor and an internal combustion engine. They can run a short distance lightly laden on battery power alone but once the battery pack runs low or with a heavy load they need the internal combustion engine to act as a generator and recharge the battery pack.

When under load or if quick acceleration is required, the hybrid’s electric motor is usually insufficient and so the petrol/diesel motor chimes in to provide the necessary motivation.

A PHEV is a plug-in hybrid electric vehicle, meaning its (usually bigger) battery pack can be recharged not only by the on board engine but by plugging into the grid. A PHEV can run about 50km on a charge, although the IC engine still starts up and provides the necessary power for heavy acceleration/load conditions.

A mild hybrid has limited electric driving capacity and it’s primarily used to chip away at CO2 emissions and fuel consumption of typically larger, luxury vehicles.

A battery electric vehicle (BEV) has an electric motor or motors and a battery pack. Once its battery pack has depleted, the BEV has to be ‘re-fuelled’ with electricity from an external source.

A Fuel Cell Electric Vehicle, like a BEV, has an electric motor but the way it's powered is different. The FCEV’s fuel cell allows a chemical reaction between hydrogen and air to create electricity to run the electric motor. The FCEV holds a tank of hydrogen onboard, that requires refilling much like an IC vehicle does.

What’s good about EVs for towing?

Because electric motors are so efficient (90 per cent of available energy to drive the wheels versus about 30 per cent for IC vehicles) and can belt out maximum torque at zero revs, they are the ideal towing motor.

Electric motors are capable of pumping out huge torque, too: 1074Nm in the case of the Tesla Model X P100D.

Battery packs are heavy, adding weight to the EV, which is an advantage for towing stability.

Also, recreational tow vehicles are not always towing. So when using an EV as a solo runabout while the van is set-up at camp or when at home, you get all the fuel (or energy)-saving benefits.

The not so good

The big problem with BEVs is how to keep the ‘fuel’ (electricity) up to the motor when towing.

As we discovered when we tow-tested the Tesla Model X,  BEV towing range is quite limited -- it was 300km on our easy test, but throw in a headwind or mountainous terrain and it’d be quickly reduced further. There’s no doubt range anxiety is only magnified when towing with a BEV.

Then there's recharge time. While fast-charging at a DC-to-DC charger can see battery packs re-charged to around 80 per cent capacity in as little as 20 minutes, a full charge can take a lot longer — especially if you’re stuck somewhere remote with a low battery percentage and need to use a 10amp wall socket -- it can take more than a day to regain a full charge.

The main problem with FCEVs (beyond the fact there are none in volume production yet that can tow) is infrastructure -- hydrogen refilling stations are almost non-existent in Australia. Yet FCEVs shouldn’t be dismissed-- the FCEV’s quick refuelling ability may well see them being the long-range towing go-to in years to come.

That leaves hybrids as the only viable solution today, but even then there are constraints. With the weight of a heavy caravan behind, the hybrid will be relying almost exclusively on the IC engine to accelerate and maintain highway speed, so there will be no fuel savings or emissions reduction there.

What’s available now?

If you want EV technology in a tow vehicle, you’ll have to pay for it. They are all top-shelf luxury SUVs.

Of the BEVs, the Tesla Model X with 2250kg is the most capable. The Audi e-tron and Mercedes-Benz EQC both have a 1800kg towing capacity - but neither arrives here until next year.

Hybrids are better: there’s the Porsche Cayenne E-hybrid (3500kg towing capacity) and the Range Rover PHEV and Range Rover Sport PHEV, both with 3000kg capacity.

Toyota's new RAV4 Hybrid can tow up to 1500kg, so will only be suitable for relatively lightweight towing jobs.

What about the future?

Technology is developing quickly. While electric motor propulsion probably won’t change much, energy storage and capture is likely to look very different. That is, faster and easier capture and better storage out of lighter battery packs. That’ll make for better towing EVs.

Development of hybrid drive caravans — where the van has its own electric motor to help propel the rig — could also be a game changer for EV towing. Further to that, a van’s ability to contain large battery packs and large solar panels could see it becoming what a jerry can is for today’s IC tow vehicle.