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The demonstration showed that there was no change in the operational status of the i-MiEV when Lock-Out/Tag-Out is done in the wrong order. The vehicle remained fully operational even with the 12-volt battery completely disconnected. The vehicle’s interior READY light remained on, the hazard flashers continued to flash and the headlights burned bright. When placed in gear, the vehicle was able to be driven.
In this case, a second source of 12-volt electricity, routed from the high-voltage battery through the DC-to-DC converter, continued to provide enough 12-volt power to operate the vehicle.
The lesson learned with this research was that the seven-step sequence for powering down an EV is very important. In situations where rescuers gain access to the 12-volt battery before the ignition is turned off, they should wait until the inside rescuer turns the ignition off. If the ignition is turned off first followed by taking away the 12-volt power, everything will power down as expected. If the ignition is still in the ON position when the battery is worked with, nothing will happen.
This information also justifies why responders should become familiar with the two alternate methods of powering down an EV when the ignition cannot be accessed due to crash damage or vehicle location/position. Many manufacturers recommend working with their vehicles’ manual disconnect device or will even state that responders could pull electrical fuses in a certain circuit panel box on the vehicle. These options are available within the specific manufacturer’s emergency response guide for its electric vehicle. All available guides for all existing hybrids as well as electric vehicles are available free of charge.
The National Fire Protection Association (NFPA) has conveniently assembled all these guides on its electric vehicle training website. Visit www.evsafetytraining.org to review and download any documents that are of interest at no charge. They are great for training purposes and will stimulate discussion among your rescue personnel as you discuss EV emergency procedures. n
TASK: Given an electric plug-in vehicle to review and inspect, the rescue team shall practice vehicle and electrical system shutdown procedures following the recommended sequence provided.