Simple and clear LED question. LEDs pop and break

[llatosz]

Attached is a picture of my set-up. It is very simple and if for a car (12V)

The LED kit comes with 3 options: Hard wire install, cigarette lighter install, and 9 + 9 V battery demo.

The peculiar thing is when I connect the hard wire install plug (shown at the top of the picture) to a 6-parallel switch, it made a loud 'pop' noise and then no longer works with the other options. Before breaking the lights, both of the other options (shown below the 6-parallel switch) worked just fine. The equivalent 18 V battery didn't even destroy the lights, so why did the simple switch connected to the cigarette lighter at 12 V destroy the lights?

 

[scottdave]

First, are the 9 volt batteries in series (creating 18 volts) or parallel (9 volts)? What is that circle dial with the rainbow colors? I am just trying to figure out what was going on. Perhaps the one plugin thing had a resistor built in? The 9volt batteries will have internal resistance. Hooking straight up to a 12volt car battery without any resistance, would blow LED's, unless there is some resistors in that box. So right before they blew, did they glow (or flash) at all before frying, or just blow?

 

[llatosz]

There are resistors built into the led strips, one resistor for each LED. The circle dial is just a color controller and has one input and two outputs (it can output one or two LED strips).

I cut open the covers on the 9V batteries, and they are in fact connected positive to negative in series, making 18 volts.

They fried without the slightest flash.

 

[llatosz]

Another thought I had was it could be due to current build-up since I did not connect the negative wire to ground. But since the cigarette lighter plug has two wires coming out, it implies that the negative terminal on each of the 6 switches are connected to ground through the cigarette lighter, so that cannot be a possibility