2nd Chance Camaro - Let the Project Begin

[Vimes]

Ya know I have been going back and fourth on this for weeks if not months. For years I have done it this way but that doesn’t mean it’s correct. Any chance you can help my brain and explain to me why it should be on the ground side. Which I feel is where it should be.

The same reason that GM went to ground switching - inrush current. It's harder on components to have current rush through than it is to have current present. Think of it this way - electricity acts a lot like water in a hose. Voltage is like pressure, and current is like flow. Say you have a 100 ft water hose that's empty, and you turn on the faucet at the wall. When you open the hose sprayer on the other end, it jumps, kicks and spurts until the hose is full. For a short time, you'll even see more pressure on the hose than the water main makes due to the water's velocity as it goes through the hose. When it slams into the end, it pushes pressure back down the hose until everything equalizes. That would be a positive switch. On the other hand, if the hose is already full and you pull the hose sprayer trigger, it sprays smoothly. That would be a negative switch. Inrush current will act much like water rushing to fill an empty hose, and it apparently causes enough problems that GM was willing to spend the money to retool every car they make to use positive switching.



About the only place you'd want a positive switch is on a racing emergency disconnect - the idea being that in an emergency you want power killed completely. The disconnect should isolate both the battery and the alternator from the power circuit because the alternator should be connected directly to the battery and not passing through the disconnect. When the disconnect is opened, the alternator's output wire is no longer connected to the car's electrical system. An emergency battery disconnect is only concerned with not catching fire, not component life.