Torque Shop: EV owners should study the manual for towing car
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The wheels that are connected to the transmission should not be on the ground when the vehicle is towed.
PHOTO: UNSPLASH
Shreejit Changaroth
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When it comes to towing a vehicle, whether it is an internal combustion engine car or an electric vehicle (EV), is there a universal way?
How a vehicle can be towed depends on which wheel axle is driven – whether it is a front-wheel drive, rear-wheel drive or four-wheel drive.
Towing a front-wheel-drive car is quite straightforward. As long as the front wheels are secured to the tow beam and lifted off the ground, with the parking brake released, the vehicle can be towed away.
It is the reverse with a rear-wheel-drive car, in which the rear wheels are lifted instead.
Even with the parking brake released and the selector in Neutral, allowing the driven wheel to be running on the ground should be avoided, other than to move it for a short distance, such as when the car is stranded in an unsafe location or is obstructing traffic. Automatic transmissions will get damaged if the wheels are turning. However, there are no such concerns with towing a rear-wheel-drive car with the front-end lifted if it has a manual gearbox.
A four-wheel-drive vehicle cannot be towed in the conventional manner. Applying similar logic as above, the transmission should not be driven by the wheels. In fact, lifting either axle to tow would be impossible as the wheels that are on the ground would not roll if the other two wheels are locked onto the tow beam. Hence, to move an all-wheel-drive vehicle urgently, the only option is to pull it using a tow rope with all wheels on the ground.
The safest method to tow a four-wheel-drive vehicle is with a flat-bed truck or four-wheel dolly. In either case, all four wheels do not touch the ground when the vehicle is towed.
The same rules apply for EVs. Although most EVs do not normally have multi-speed transmissions, allowing the driven wheels to roll while being towed can cause reverse power flow akin to energy recuperation, which in theory means generating a few hundred volts of electricity.
On most current generation EVs, there is a free-roll function specifically for towing. This would be in addition to releasing the electronic parking brake and switching from Drive to Neutral. The procedure to disable the e-brake and selecting Neutral may vary depending on how the manufacturer has designed the steps.
As an EV owner or driver, study the manual to note any advisory on towing. It would be best not to rely on the tow truck operator’s suggestions, and you should stipulate the rules to observe during towing.
The safest type of recovery vehicle to engage is, of course, a flat-bed truck.
In the highly unlikely event that the low and high voltage systems are dead at the same time, it may not be possible to release the car from the Park mode. When this happens, a new 12-volt battery would be needed to recover the vehicle.
