My wife and I have recently added a tow bar to our Hyundai Kona electric car and successfully completed a test run with our newly-acquired camper trailer.
We drove from our home in Canberra to Narooma on the NSW south coast, stayed two nights and returned to Canberra.
Before recounting the details of that trip, first I’d like to explain how I concluded that this would probably not end in disaster, in spite of Scott Morrison’s warning: “I’ll tell you what – it (an EV) is not going to tow your trailer … It’s not going to get you out to your favourite camping spot … Bill Shorten wants to end the weekend”.
Last year, an article in The Driven described using a tow bar intended for a petrol Hyundai Kona on the electric version of the Kona. The petrol Kona has a tow rating of 1300kg braked or 650kg un-braked, with a tow ball load limit of 130kg.
The article discussed practical and legal concerns about towing with the electric Kona in light of Hyundai’s instruction book simply saying “not recommended” without providing a tow rating or elaborating on the topic. One suggested reason for Hyundai declining to provide a tow rating was that car’s range estimates could be inaccurate.
A follow–up article in The Driven described an extended trip with a light weight trailer and two kayaks behind that Kona. This was followed by an example of a Tesla Model 3 towing 6 canoes and other gear for scouts.
I was inspired to consider buying a camper trailer or small caravan of some sort to use with our electric Kona. This would be a step beyond the examples above so I did further research before diving in.
In particular, I noted a comment under the first article suggesting that another possible reason for the Hyundai’s “not recommended” comment could be that the tow ball weight of a trailer might cause the rear Permissible Axle Weight (PAW) to be exceeded even if overall load limits were not.
Hyundai Kona Electric Published Specifications:
Kerb Weight: lightest 1685kg / heaviest 1743kg
Gross Vehicle Mass (GVM): 2180kg
Permissible Axle Weight (PAW): Front 1100kg / Rear 1120kg Towing limits: not specified.
Combining the front and rear PAWs, 1100kg and 1120kg, yields 2220kg, a number not much greater than the GVM (gross vehicle mass) of 2180kg. In contrast, the sum of PAWs of the petrol Kona exceeds its GVM by a greater margin. This suggested that there is more latitude to distribute mass unusually in the petrol version. The comment started to make some sense.
The petrol Kona is likely to be nose-heavy, in common with many petrol vehicles. It would have a heavy engine and gear box at the front with a relatively light-weight empty shell behind.
One could keep adding quite a lot of mass from unusual combinations of people, luggage and/or a tow ball load onto the rear and the weight distribution would probably be only improved before one eventually overloaded the vehicle.
In contrast, the electric Kona has a lighter electric motor up front and a heavy battery across the whole floor area between the front and rear wheels, presumably shifting the centre of gravity rearward.
This is consistent with the idea that there might be less scope for adding unusual rearward weight before the rear axle would be over-loaded.
So, could there be a grain of truth in the idea that electric cars are not suited to towing? In spite of their excellent torque, perhaps the balanced weight characteristic that often gives them excellent handling also puts limits on their ability to take a tow ball load?
While the electric Kona permissible axle weights were published, I did not know the actual axle loads of the empty car, so I had mine weighed:
Measured Weights Kona electric Highlander:
Front Axle – 976kg
Rear Axle – 844kg
Total mass – 1820kg*
(*This happens to be 77kg more than Hyundai’s heaviest specified kerb weight and I now wonder if perhaps the person who did the weighing stayed in the driver’s seat. If so, they would have added about half their weight to each axle.)
Now I could do some back-of-envelope estimates of axle loads. When my wife and I would travel with a trailer there would be just two of us in the front of the car and no rear passengers.
We had narrowed down the style of camper trailer we would like and I had surveyed advertised tare masses, GVMs and tow ball weights. Certainly there were some options with specifications well within the tow ratings of the petrol Kona.
My wife and I in the front seats would have a combined mass of about 140kg. We could apportion 70kg to the front axles and 70kg to rear because the front seats are about equidistant between the front and rear wheels.
Luggage strapped into the back seat and in the luggage area behind the back seat would be about equally just ahead and just behind or over the rear wheels, so I could count that entirely towards the rear axle load.
This could be a conservative assumption because I could deliberately place heavier items just behind the front seats and use the rear luggage space for bulky but lighter items. I also have a ‘Frunk’ (or froot) on order to move my collection of charge cords to a luggage area under the bonnet.
At this stage we had Jayco’s lightest currently–made camper trailer under consideration. It has a 65kg Tow Ball Weight (TBW) and an 870kg tare weight, well under the rated limits of the petrol Kona. Added weight from kitchen and other equipment would be almost directly over the trailer axle in this design so one could add realistically to the trailer’s tare weight while staying well below the petrol Kona’s total mass limit and not changing the TBW by much.
The tow bar itself would add about 13kg according to the installer. The overhang of the tow bar behind the rear axle is very short on the Kona so the tow ball load should appear straightforwardly on the rear axle with only minor leverage effects on the front wheels. So, what axle loads did I estimate?
Front Axle: The sum of 976kg, the empty mass, plus 70kg, half of the mass of the people in the front seats, produces1046kg, which is 54kg short of the 1100kg front PAW.
Rear Axle: The sum of 844kg, the empty mass, plus 70kg, the other half of the mass of the people in front seat, plus 13kg for the tow bar plus the 65kg tow ball weight plus a 50kg guesstimate for luggage produces 1042kg, which is 78kg less than the 1120kg rear PAW.
This estimated front axle load (1046kg) is almost exactly the same as the estimated rear load (1042kg) and their combination (2088kg) is 92kg under the GVM (2180kg).
I concluded that two people, a camper trailer of this sort and a reasonable luggage allowance would not exceed any limits so long as there are no passengers in the rear seats. Neither individual axle ratings nor the GVM would be exceeded.
The front/back weight balance would be close to 50:50, which is generally regarded as ‘a good thing’ for vehicle dynamics. Nonetheless, taking care to pack heavier items more forward in the rear of the car might be beneficial.
However, one could overload the electric Kona in some not-unrealistic scenarios such combining a trailer with rear passengers and heavy luggage. It seems that pulling the petrol Kona’s rated trailer load with the electric Kona could be done safely if care were taken but it would be less ‘idiot-proof’.
I suspect that Hyundai preferred to not provide a rating that they would need to either surround with caveats or make very low in order to cover plausible scenarios.
Having concluded that we were unlikely to have problems in our particular scenario, we were lucky to find a second-hand 2010 Jayco Flite camper trailer with a 55kg TBW and 769kg tare weight according to its compliance plate.
This is a bit lighter than any of the current camper trailers that I could find in this style with an internal kitchen and seating. I actually measured about 72kg TBW as loaded ready for travel including a full gas bottle, cooking equipment and accessories such as bed end flies and an awning.
A trailer of this mass must be braked according to both Hyundai’s unbraked limit for the petrol Kona (650kg) and the default that applies in the absence of a manufacturer’s specified limit (750kg).
Our trailer has electric brakes so we needed an electric brake controller in the car. I chose a controller that detects deceleration of the tow vehicle and automatically applies a proportional signal to the trailer brakes. When using regenerative braking on a downhill to maintain a constant speed, the trailer brakes are not applied since there is no deceleration.
This has the benefit of allowing the car to maximise its recovery of energy into the battery. It will still waste some kinetic energy by applying the trailer brakes when the car is actually slowing. That can be adjusted down on the controller but obviously we do want leave enough braking for safety. The controller also has a button to apply the trailer brakes manually, which one might want to do if the trailer were to start swaying.
Our trial run from our home in Canberra via Bateman’s Bay to Narooma on the NSW south coast and back was 225km in each direction with a change of elevation of 650m. The King’s Highway from Canberra to the coast at Bateman’s Bay is hilly. It has steep sections with grades exceeding 15% and a total ascent and descent along its length of 1583 m and 2465 m, respectively.
The trailer felt very stable. The electric Kona easily pulled the trailer on the steepest sections of Clyde Mountain with ample power and torque and no adverse effect on steering. I noticed a bit of jerking on uneven surfaces but otherwise the trailer had little effect on the car’s performance or comfort for normal driving.
Unsurprisingly, the trailer does have an effect on efficiency, just as it would behind any tow vehicle. I gave myself a self-imposed speed limit of 90kph for better efficiency but otherwise I did not drive much differently from how I would take that road without the trailer. We left home with a full charge and arrived at Narooma with 29% state of charge.
We commenced our return trip with a full charge but stopped for a quick 14% top-up at the Bateman’s Bay NRMA 50kW charger while we got a coffee because we had a substantial gain of altitude ahead of us.
We arrived home with 33% charge remaining so it turns out we could have just driven back without the top up. For the trip to the coast, the car reported 20.2kwh/100km and for the up-hill return trip it said 24.4kWh/100km. So, 22.3kWh/100km overall, about a third knocked off the range, from over 400km to just under 300km.
We stayed in Narooma for two nights. Caravan parks with powered sites generally have one 15A outlet per site. We plugged the camper into the 15A supply and charged the car from the camper’s external 10A outlet. We have an EVSE charge cord that can be adjusted to lower current limits.
At first we set it to 6A while we used higher powered devices such as a kettle, a toaster, a microwave or a portable single ‘ring’ induction cooktop and set it back to 10A when we were using only lighter loads such as the camper’s fridge and lights.
Later we left the car taking 10A and neither the site’s 16A circuit breaker nor the van’s 16A breaker tripped while charging the car and running any of the higher powered devices one at a time along with the fridge and assorted small loads. After the first night we were recharged to about 75%.
After some local driving on the second day without the trailer and the second night of charging, we were fully charged for our return trip to Canberra.
We could have cheated for 50% faster charging by plugging the car into a neighbouring site’s 15A outlet but we did not want to do that. If anyone were to ask, we wanted to be able to show that we were taking no more than the 15A supply we had paid for with the site. It is early days for EVs in caravan parks and we did not want to create a poor impression.
Extended trips staying a few nights at each of a series of caravan parks up to 250km apart would be easily achievable without needing any charging options besides powered camp sites. Longer daily distances would be easily achieved by planning for toilet, coffee and meal breaks to coincide with DC fast charger locations.
In spite of the prime minister’s warning, our first EV camping weekend was not ruined!