Charging mobile devices

Years ago I worked in the Burroughs product engineering lab. One of my projects there was studying the effect of switching power to devices. I used an oscilloscope in a single trace mode to see what happens when a mechanical switch turns a device from off to on. The result was that mechanical connection is not a simple transfer of power. There is a whole series sparking that goes on in the first half second of connection. During that first half second the two conductors can transfer minute amounts of metal and wear down the surfaces and the voltage spikes can even weaken or destroy the internal components.

Recently I have noticed when plugging in a charger to recharge a laptop computer, if the room light is dim I can see a spark as the plug is inserted into a wall socket. It happens with all three of my laptops and at both homes I have lived in. Plugging a charger into a wall socket is the same as throwing a mechanical switch. My thinking is if you plug the cord into the mobile device first and then plug the charger into the wall socket; you will keep the wear and tear down on your device and its immediate internal connection.

One more thing, when unplugging a cord from a wall socket, do not just yank on the cord itself. Grip the molded plastic at the end and pull. Modern cords do have strain reliefs, but eventually the copper conductors will try and pull away from the pins that make connection in the wall socket and that can cause overheating when the connection is poor and potential for a flameout.

As always, I could be wrong.