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November 7, 2019

Lessons Learned While Dolly Towing an EV

By: Rob Lowe

Featured Picture

After 50 km (30 mi.) Check Straps

Retaining straps Our first long trip while towing an EV on a Tow Dolly was interesting. Loading the dolly becomes easier as we familiarize ourselves with the process of forming a ‘basket’ of the webbing used to secure the tires. It is an evolving process that is refined each time we load the car. We’ve learned that the 50 km (30 mile) stop to check and adjust the webbing of the ‘basket’ is critical, since after towing the EV for that relatively short distance, the straps are looser and must be re-tightened. While it may seem to be an inconvenience to have to stop to check, it is far better to do so than to risk having the car loose on the tow dolly. In addition to finding the straps looser, we have had one instance where one strap came off the tire completely and was laying beside the tire on the dolly. Over time we have also refined our method of attaching the straps to the dolly to make them easier to install after the car is loaded and allow the straps to be tightened to secure the car to the dolly. We’ve learned through use, how to install the safety retention chain to the car’s suspension and the dolly frame, so that a loose strap does not result in the car coming off the dolly. A proper inspection at each rest stop is essential, although as we become familiar with the loading and strap tie down procedure, it becomes routine. We’ve also learned that the wiring connection from the EV to the tow dolly need not be very long with about 30 cm (12”) of slack in the wiring sufficient for all turning that the car does while being towed on the dolly.

 

Add Rear Lighting to Towed Vehicle

EV Lighting While Dolly TowingWe highly recommend the addition of rear lighting on the EV which is connected to the tow dolly’s lighting wiring that in turn receives its power supply from the RV. With this additional lighting, the bright lighting on the tow dolly combined with the LED lighting on the side and rear of the RV, turns that are signalled result in those following us, giving the required space to allow us to change lanes or merge safely.  

 

Braking is Different

Braking is somewhat different when towing with a tow dolly versus flat towing using an independent tow vehicle braking system. The tow dolly has a surge braking system that needs to sense a difference in speed between the towing RV and the dolly using that surging speed of the dolly relative to the RV to brake the EV. This is slower by nature than a typical electrically or air operated tow vehicle braking system. We’ve never felt as if we did not have any tow vehicle braking, it is delayed in applying the brakes when we apply the brakes in the coach and wait for the surge brake to react to the slowing RV.

 

Avoid Adding Axle Grease

The EV tows well on a tow dolly. We did notice that one side’s axle was warm after towing with grease strips spread around the radius of a tire. When we bought the slightly used dolly, the previous owner had greased the axles using the built-in grease fitting. We had only towed a relatively short distance with the EV on the Tow Dolly, however before our trip and after reading the Master Tow instructions, I decided to re-grease the bearings. After seeing the grease on the tire, and noticing the raised axle temperature, I had the tow dolly inspected by a dealer. The technician replaced the rear seal on the axle (although he admitted that it did not seem to be leaking) as well as the two grease fitting rubber caps. His experience with this brand of tow dolly was that people were excessively greasing the axles (following the Master Tow’s (maker) instructions) and creating the problem we experienced. His suggestions was to forgo adding lubricating grease unless and until there was evidence of grease leakage. In other words, more damage was potentially occurring from over-lubrication than from not lubricating the axle bearing. We will follow this advice going forward.

 

Load Dolly with it Straight

Another item that we noticed is that loading the dolly should be done after the dolly is pulled straight ahead by the RV and loading on a relatively level road surface. This is important since the EV battery hangs below the floor of the EV and the tow dolly loading ramps can contact the bottom of the battery if not level and straight behind the RV. Once the car is on the dolly and strapped into place there is 5 cm (2 inches) of space between the battery bottom and the loading ramps, which is sufficient to reduce any contact between the two while towing the EV down the road.

These lessons are all part of the learning process that comes with using a tow dolly to tow a vehicle after decades of flat towing many vehicles. Every change in vehicle required some adjustment to the new towing system and vehicle. Changing to an alternative method of towing heightens the changes and extends the adjustment process.

 

EV Brake Rotors May Corrode

One slight change in the towing procedure, then driving the EV was that after towing on a day of extended rainfall, then driving the EV, the EV hydraulic brake rotors ‘corrode’ (become rust covered) slightly. Afterwards, if the EV braking requires those brakes to be applied, in addition to the regenerative brakes, there is some noise associated with harder braking the first time as the ‘rusty’ rotors contact the brake caliper pads. Under typical EV braking, the hydraulic brakes rarely get much use. The EV uses the regenerative brakes for the vast majority of its braking. This is a short term, once or twice occurrence and only after towing in heavy rain.

 

Remember that Length is Longer When Dolly Towing

The other adaptation to towing using a tow dolly when compared to flat towing a vehicle is the extended distance that the vehicle on the tow dolly is behind the RV. This comes into play primarily when negotiating a tight turn, since the coach negotiates the turn and then it takes longer in distance and time for the towed vehicle to clear the turn and the curb nearby. What this means is that the RV must drive farther in the forward, straight-ahead direction, before turning to complete the turn. It is easy to see in the rear camera and side mirror and it takes only a few turns to adjust to the additional length when driving to accommodate the tow dolly and car.

Tow Dolly with EV on behind RV

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