Caravan & Trailer On The Tow Hitch — How It Affects EV Range

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What happens to the overall range of an electric car when you tow a caravan or a trailer? The association of Danish EV owners (FDEL) decided to find out, and with the authors’ permission, here follows a translated version of the findings:

In this test, the electric car association examines how different types of trailers affect energy consumption and range. Read on to find out how to cover your needs.

Many are used to having a tow hitch on fossil fuel cars. Thus it is only natural to be in demand on electric cars. Martin Messer Thomsen from the Electric Car Association’s test group has tested the energy consumption and range with different types of trailers on a cold December day in 2020.

We have chosen a caravan weighing 1,000 kg, a closed hauling trailer weighing 360 kg, and an open trailer weighing 270 kg. For the tow job we used the Tesla Model 3 LR (Long Range) without heat pump and with winter tires. Model 3 is the cheapest electric car on the Danish market that can tow 1,000 kg. If you want to tow more than 1,000 kg, you need an Audi e-tron, Mercedes EQC, or Tesla Model X, which are all more expensive. In 2021, the cheaper Volkswagen ID.4 will be on the market. It will be able to tow 1,000 kg and 1,200 kg respectively depending on the choice of battery size.

Weather Conditions During The Test:

• Wind speed 3–5 m/s
• Wind direction: south
• Temperature 5–7 degrees centigrade
• Tests were performed around Christmas, December, 2020.

Similar temperatures and wind speeds can be experienced in both the Easter and autumn holidays, where many use a caravan.

The Tesla Model 3 is available in 2 battery sizes, both of which can be supplied with a tow hitch. The performance version is not available with this feature.

The tow hitch must be fitted at the factory and cannot be retrofitted.

The test took place on a route on the motorway from the Supercharger in Køge, southwest of Copenhagen, to the Supercharger in Nørre Alslev on the island of Falster — a distance of 76 km (47 miles) — making it possible to do a roundtrip accounting for wind in both directions.

Tesla Model 3: Energy Consumption & Range With Trailer

1. Calculated from 70 kWh usable capacity (of the battery size)
2. The caravan weighed 1,000 kg including cargo
3. Trailer had no load, but may load 390 kg with a total weight of 750 kg
4. Trailer had no load, but may load 480 kg with a total weight of 750 kg
5. Driving on motorway without a trailer at 110 km/h (68 mph).

Wind & Shape Of Trailer Is Crucial

As can be seen from the table, the wind is of great importance when towing a trailer. This applies to both electric cars and fossil cars. Model 3 is in itself very aerodynamic, but the aerodynamics are canceled out when the wind is carried directly into the trailing large surface area.

Despite the fact that there was only a light wind of 3 to 5 m/s on the test day, it still resulted in a difference in the potential range for each direction of 35 km (22 miles) with the caravan: 175 km (109 miles) in headwind and 210 km (130 miles) in tailwind. With wind strength and direction being of so much influence, it can be difficult to predict consumption. Therefore, you should be cautious about the range potential and not plan to run the battery all the way down near 0% in the attempt to reach the next charging station. The actual range with the caravan is thus estimated to be 130–150 km (81–93 miles). Is that acceptable?

Many people will probably refrain from driving longer trips with such a large caravan, but it will definitely be feasible to take it on shorter trips, for example around the relatively small country of Denmark. It is possible to drive from, for example, Copenhagen to Blåvand (326 km, 202 miles) on Jutland’s west coast with 2 charge stops in Slagelse and Middelfart, respectively.

The closed hauling trailer has a smaller front area than the caravan to take the pressure of wind and it weighs less. This results in a slightly longer range of between 180 and 210 km (112 to 130 miles). A haul from, for example, Aalborg to Odense (255 km, 158 miles) would require a single charge stop midway in Hedensted.

The flat, open trailer provides only a small reduction in range in both headwinds and tailwinds. Here, a realistic range would be 250 to 275 km (155 to 171 miles), if you can keep the load down and flush under a cover. A trip from Herning to Ringsted (249 km, 155 miles) would be possible without charging.

Do you have experience driving an electric car with a trailer? Do you recognize these numbers?

Charging With Trailer Or Caravan

Charging stations are generally not designed to charge an electric car towing a trailer or caravan. This is how it went down at the Superchargers we tried:

All photos and video by FDEL.