First let’s take look at why we should not “drag” or “roll” a high voltage vehicle. Later we will provide some options for loading and transporting. Electric and Hybrids are powered by electric motors. In the case of a fully electric vehicle the electric motor provides all of the power for the drivetrain and in hybrids the drivetrain is powered by a combination of an electric motor and an internal combustion engine. In either case when the vehicles wheels are turning but the motor(s) are not being used to power the drivetrain (during coasting & breaking), the electric motor becomes a generator of electricity. The power generated during coasting or braking is often call regenerative breaking and is sent back to the battery to recharge it.
This design works well for extending the range of the vehicle but can create some issues when the vehicle is shut down and being rolled because the power generated has no where to go. If the vehicle is in a non-operational state, the energy generated in the motor will result in overheating of the unit and will likely result in damage to the motor and possibly fire!
So how far and fast can we drag a hybrid or electric vehicle? The manufacturers recommendations should always be followed and can be accessed at no cost by simply calling the Energy Security Agency. Here are the basic guidelines that will apply to most high voltage vehicles.
- Do not roll on drive wheels over 1 mph
- Do not roll on drive wheels for long distances (only as far a absolutely necessary to transport properly)
- If the vehicle has been rolled on the drive wheels for long distances or high speeds check for heat and fire before transporting
- High voltage shutdown procedures will NOT make the vehicle safe to roll
So what is the solution? High voltage vehicles should be moved on dollies, flatbeds/rollbacks or in another way that does not roll the vehicles drive wheels. Be sure your dispatch knows if the vehicle is a hybrid or electric so you can respond with the appropriate towing apparatus.
In other tech tips we will look at “tow mode” in Tesla vehicles and more – Sign up for our newsletter to be notified!
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