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So I almost blew up my car this afternoon.....

Rjackson32

NAXJA Forum User
Location
Westchester
I am in the process of selling my car. Someone called me and wanted to come see the car and was about 10 minutes away from my house. I told him to come over and check it out and then realized that the battery had died. I went to jump it but it was past the point of being jumped. Since NAPA was closed I took the battery out of my 99 M3 so that the guy would be able to testdrive the car when he arrived. The battery was a bit bigger, about 2 or 3 inches and I had to work to get it in. Also the terminals were slightly larger. I was rushing and didn't get the negative terminal on all the way. I thought it would be sufficient....

As soon as I touched the positive cable to the terminal it sparked (it wasn't a crazy amount of sparking, nothing I haven't seen before) and so I went forth with putting the positive wire onto the terminal. A few seconds after my fuse box started sparking...smoking...caught on fire. I ripped the positive wire off the terminal, grabbed the top off the fuse box and noticed that the green wire coming out of the fuse box was on fire. I grabbed the fire and put it out.

After collecting myself I tried it again. This time securing the negative wire onto the terminal. Then slowly touching the positive wire to the terminal. As soon as I did this my horn started blaring (as it was doing while I was putting the fire out originally) and the fuse box started sparking again.

I postponed the testdrive..obviously..but he is coming back to see the car tomorrow at 5. I need to get this fixed. I don't want to loose the sale. What kind of damage do you think I did?

130.jpg
 
are you 100% sure the battery from the BMW has the positive terminal on the same side? I thought it was reverse of the Jeep. It sounds as though the battery was hooked up as positive grounded.
 
maybe you pinched a fusible link persuading the battery in and when you hooked it up *poof*
 
bcmaxx said:
maybe you pinched a fusible link persuading the battery in and when you hooked it up *poof*

I thought of that too, but it wouldn't cause more than the one wire to "poof"-- if the fuse box was "poofing" as well, it seems like everything was shorted to ground...... :dunno:
 
sounds like you put the beemer battery in backwards. the terminals not fitting correctly kinda tipped me off. make sure the battery is installed correctly then look for blown fuses.
 
....i put the f-ing battery in backwards...well fuck me sideways. That is definitely possible. To clarify, the only thing that was on fire was that green wire. There was only smoke coming out from under the fuse box. Thanks guys.
 
Rjackson32 said:
....i put the f-ing battery in backwards...well fuck me sideways. That is definitely possible. To clarify, the only thing that was on fire was that green wire. There was only smoke coming out from under the fuse box. Thanks guys.

i did that once.....it was intersting to say the least
 
If it makes you feel any better I destroyed the drivers side door on my old van. By while lubin up a lock cylinder and thinking wow that would be cool to just burn off the excess on the out side of the door. My door made a bit more than a poof though.
(It was one of my first cars, give me a break)
 
hooked up the battery backwards. are those fusable links? if they pull like a rubber band they are and they are blown. replace the wires that burnt, replace as much of the wire as possible, use the same gauge, if it is fusable links use teh correct size to replace. make sure you do good connections I.E. solder or even high quality crimps, dont just twist the wire together and wrap in tape. cover the connections with shrink tubing. inspect all the wires in the loom to make sure that none of those burnt, I suspect more then just the couple wires in the pics becasue of the horn blaring but Im not familiar with the harness you have.
next time something catches on fire please dont just hook it back up without inspecting/repairing anything that could be damaged.

nominated, several things are nominated!
 
did you say you put the negative terminal/cable on first?
 
That's what I was thinking...rule of thumb is...neg cable disconnected first, connected last.

Doing it the other way around could create a power surge in the electrical system. Because here in the states, we go by the 'Benjamin Franklin' current where electrons 'flow' from positive to negative...but in reality, electrons flow from from negative to positive. Electrons are negative charged particles...what do you think makes negative, negative?

think of it as water pressure...you have two water hoses...one with high pressure water (neg cable)...and one with no pressure (pos cable). If you connect the neg cable first to an empty tank...that tank (could) fill up with high pressure water by the time you connect the pos cable...and you might get splashed and wet. If you had connected the pos cable first and then neg cable second...all that high pressure water would flow into the empty tank with no splashing.

Of course, hooking up a battery backwards will do it as well...
 
BMW is backwards....at least my 85 bmw 325e was. Black was hot, red was ground. stupid, but that's what it was.

I never would have been able to remember except for the red wire ran from the battery terminal directly to a big ground lug on the body about 1' away, and the black wire came into the battery compartment in a channel (ran up to the front of the car and into the engine bay - the battery was in the trunk).
 
well currently one battery has both black and the other both red. since they run parallel its easy to mix them up if someone isint carefull. I do that randomly thru the rig, that way if someone tries to mess with it they have to stop and study it or burn a wire or 2.
 
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