Yes, the car will be killed when you flip the switch but the wire will be hot all the time. The relay prevents that.
Guess I dont see the issue with itt being " hot" when the car is turned off. The battery is " hot" too when the car is turned off.
??
Not a huge deal, until you think everything is off and put a wrench on the alternator to remove it and create a bunch of sparks when it hit's the frame. I've done that a few times pulling the motor prior to fixing it with the relay. I also think about the case of a wreck, and something pinches the wire from to the alternator to the battery. I want everything off from the batteries forward when the switch if off.
