[Bimmerroad]

I unplugged by battery to do some work under the hood, had to service the turbochargers, water pump and a few other parts.

I had to put the car on neutral to move a bit, when attempting to reconnect the terminals.

I attached positive first, when attempting to reconnect the negative it sparked and melted the terminal first (just a bit).

Some of the electrical connectors are unhooked as I am still working on it, I was careful enough to cover them with plastic sleeves to avoid damage and contamination.

I cannot come up with any theory why hooking up the battery with disconnected electrical connectors would cause a short circuit.

I double checked the wires and there were no damages to any connectors, battery cables etc, they look new and it is 2012, it cannot be because of age.


Any theories out there?

I am afraid to hook it up again and cause damages, anyway of safely doing it?

[Profssor]

Keeping the positive battery cable disconnected and the negative battery cable connected, measure the resistance from the positive battery cable to ground. It sounds to me like you have a short, which likely means that you disturbed a connection or damaged a component during your repair. Start taking things back apart (as little as possible) and look for your mistake.

Joe

[Bimmerroad]

Originally Posted by Profssor

Keeping the positive battery cable disconnected and the negative battery cable connected, measure the resistance from the positive battery cable to ground. It sounds to me like you have a short, which likely means that you disturbed a connection or damaged a component during your repair. Start taking things back apart (as little as possible) and look for your mistake.

Joe

Thank you Joe

[Bimmerroad]

Fortunately and unfortunately, it was a very idiotic thing I did.

Unfortunately because I wasted time on it and

Fortunately because I found out it was my mistake.

I had removed the alternator and the cable was neglected, fell between the engine bay touching metal. It was hard to see it, just noticed after I started placing the parts in place. The short was so violent that had to be something serious like this, no malfunctioning wires connectors could hardly cause such short, any small component would had caused a less conspicuous short.

Lack of attention to all details... hope helps others to keep reminding themselves to be very detail oriented when working on their vehicles.