Bad Mistake...

[zman]

I made a bad mistake last night.

My wife had an emergency to meet her friend who had an accident. But, she found out her car battery was dead because accidently we left the light on. So, I had to do a jump from my BMW. Because it was a rush and dark, I didn't pay attention that I accidently cross the cable.

My car started OK, but her car didn't start. So, I went to check and found out about it.
I took the cable off right away. I notice that the cable became very hot. In fact the rubber that covers the cable clips started to melt.

I let it cooled for a minute and corrected the cable, and tried again.
Her car started and I found out that it had a blown fuse because of it.

My car seemed to run fine, No warning message or anything.

I am curious if I damaged anything.

 

[boomerbimmer]

If you had a blown fuse then you probably didn't damage anything. That is what the fuses are for. They are made to blow at low amps to keep something important from burning up.

 

[Drake]

My BMW only has the positive terminal present under the hood for boosting. I can just pick a part of the frame for the negative terminal. This makes it (pardon me) idiot proof... or it is supposed to.

If your cabling was ok and her's was backwards there would be a chance to damage her battery (the dead one) but likely not yours.

 

[Kirby]

The odds of damage to your car are pretty low, since the other car's battery was dead. You essentially created a 24 volt (actually less because of the dead battery) battery to battery short circuit - that's why you got the heat and melting of the jumpers. Your alternator/voltage regulator saw a heavy load at 12 volts and was trying to charge a reverse polarity battery. A bad thing but the voltage regulator should have protected your alternator.

The really bad thing is that her car essentially saw reverse polarity. Any polarity sensitive stuff in her car coulda blown. That's why you blew that fuse. Most of the sensitive stuff these days is protected (radio, computer, etc.) because they know this can happen. Hopefully there was no other damage. If you have the time, you might want to do a quick wiring inspection under the hood and dash just to check for any melted insulation.

Good Luck....