Let's cause a malfunction and see what happens in a controlled environment.
Electric cars are gradually becoming popular, but most people, even EV enthusiasts and drivers, might not know much about the safety in an event of a short circuit or other electrical problems concerning the high-voltage system.
As always, an outstanding presentation was released by Professor John D. Kelly from the Weber State University (WSU), which in a controlled environment demonstrated several examples of malfunctions, including short circuits or loss of isolation in a Chevrolet Bolt EV.
In the case of a short circuit of just a single positive or negative terminal to the vehicle chassis, nothing much happens, as the vehicle remains operational, there is no danger yet, however, it triggers trouble codes in the vehicle computer. Short circuit of both terminals (directly or via the vehicle chassis) would, of course, blow some battery fuses and shut down the entire car immediately.
The different type of problem is a partial loss of isolation, which might happen, for example, because conductive liquids leak inside the battery or other parts of the high-voltage system.
Video Description via WeberAuto on YouTube:
How safe from electrical shock are you in an electric vehicle?
Have you ever wondered how safe from electrical shock are you in an electric vehicle? Watch as I create direct high voltage shorts to the vehicle chassis, shorts through conductive liquids, and how the vehicle detects these short circuits. A 2017 Chevrolet Bolt EV is used as an example vehicle.
Introduction at 0:07
Safety Warning at 0:25
High Voltage (HV) Insulation/Isolation example at 0:40
On-Car high voltage power distribution at 2:50
Live HV measurements (Car Powered Off) at 4:55
Live HV measurements (Car Powered On) at 6:15
MUST SEE: Shorting the 381V battery positive cable to vehicle chassis at 7:36
Which Diagnostic Trouble Codes (DTC)s were set at 9:57
MUST SEE: Shorting the 381V battery negative cable to vehicle chassis at 11:18
What can happen in an automobile accident at 13:25
MUST SEE: How loss of isolation can occur through conductive liquids at 13:50
How the car performs active isolation testing and passive isolation testing at 14:41
Normal passive scan tool data values for loss of isolation detection at 16:10
See the results of an 11 Million ohm connection to vehicle chassis at 18:30
See the results of a 4.65 Million ohm connection to vehicle chassis at 20:50
See the results of a 1.16 Million ohm connection to vehicle chassis at 22:20
See the results of a 551 thousand ohm connection to vehicle chassis at 23:00
See the results of a 222 thousand ohm connection to vehicle chassis at 23:35
MUST SEE: The 318-265 k ohm threshold to trigger a loss of isolation DTC at 23:40
MUST SEE: GM On-Star notification of battery problem at 24:50
See the results of a 110 thousand ohm connection to vehicle chassis at 25:15
MUST SEE: See the results of a 0 (zero) ohm connection to vehicle chassis at 25:51
See my voltage drop measurement table at 26:54
MUST SEE: See the results of a conductive liquid connection to vehicle chassis at 27:35
How to determine the location of a loss of isolation problem at 30:00
Clearing Secured High Voltage DTCs with a GM GDS2 scan tool at 32:08
Hybrid/EV battery pack active isolation test at 33:00
Hybrid/EV battery pack heater passive isolation test at 34:35
The Megohmeter and the factory specifications for isolation resistance at 37:28
Example of using the Fluke 1587 Insulation Tester (Megohmeter) at 40:30
Video summary at 44:05
Weber State University (WSU) - Department of Automotive Technology - Ardell Brown Technology Wing - Transmission Lab.
This episode covers what happens with the high voltage system looses isolation with the vehicle chassis of an electric vehicle (EV), plug-in electric vehicle (PHEV), or hybrid electric vehicle (HEV). A 2017 Chevrolet Bolt EV is used as an example vehicle in this video.
We offer both online training and hands-on training classes on Hybrid and Electric Vehicles to the general public. Visit http://www.weber.edu/evtraining for more information.
WSU is a leader in Hybrid and Electric Vehicle education. This topic is taught as part of our 4-year bachelor's degree program. For information joining the Weber Automotive program, visit: http://www.weber.edu/automotive
This video was created and edited by Professor John D. Kelly at WSU. For a full biography, see http://www.weber.edu/automotive/J_Kel...
Donate to the Department of Automotive Technology at Weber State University here: http://advancement.weber.edu/givetowsu