I've got to jump in on this one. I can't understand what electrical engineering principle could possibly impact the requirement to connect the positive or the negative first, with respect to inrush surges as the connection is made. It's a single circuit. Current flow and resulting voltage sags/surges take a complete circuit, and will happen whether Pos or Neg is hooked up first. The surge is completely a function of the voltage offered (the battery) vs the load being connected-to (the car's electrical system). Hooking up one side or the other first makes no difference, no current flows until the final connection is made. The normal reason for connecting the positive first is that is less likely that you will touch a hot (+) wire to ground by accident, since the grounds aren't hooked up yet. Using jumper cables as an example, if you were to connect the neg circuit first, and then connect one end of the pos, and accidently drop the other one on the car body, you'd get a short and lots of sparks. If you connect the positive side first, later accidentally dropping the neg to part of the car would have no effect other than completing the circuit. Dave Swingle --- In dmcnews@xxxx, srubano@xxxx wrote: > > By connecting the positive cable first THEN the negative cable, you > eliminate/minimize any surge that is sent into the electrical system > of BOTH cars. I have seen countless amount of times people installing > new batteries into their car and connecting the ground first then the > positive lead and then wonder why all of their bulbs all burnt out at > the same time in their dash board or why their computer fried. > > Steve >