Smoking electrics

[dave]

HELP!!!!!!!!!!!!!!!!!! my mint e30 sport which i keep garaged and wrapped up during the winter i fear may be dead. I have just re-connected the battery after giving it a re-charge and, firstly the +terminal started to arc when connected and then.............a huge ammount of smoke started to emmit from under the bonnet followed by a foul burning smell. the battery has now been disconnected and i am currently sobbing at this keyboard. Can someone please save my sport?

[gareth320]

I thought I had problems with my motor...................
I know this may sound dumb but did u connect the battery the right way round? If so the the next thing to do is find out where the smoke came from. Somthing obviously melted. Find the melted looking wire. Whatever this wire supplies may have a dead short on it. If you have a multimeter use the continuity check ( beeps for dead short) to check everything. Check all systems that remain live with ign off first.
Happy hunting.

[A1BMW325iSport]

where was the smoke coming from, upload photos if you can,
do you have any aftermarket gear fitted audio/alarm wise?

[dave]

smoke appeared to be coming from under the offside sill, this was maybe due to the bonnet being shut? i have checked the fuse box and all appears to be ok, however before i saw the smoke all the electrics went tits up. The window switch worked backwards the stereo did'nt work but the lights and fan worked ok, i am totally baffled cos i have owned the car for 6 years and garaged it every winter!

[kevin316i]

Any chance a rodent might have gotten into the garage and chewed some wiring in the car that caused some shorting? This could be a red herring, but no harm to have a good look over (and under) the car to see if there are any traces of rodents having been present (droppings, chewed bits of insulation, etc.). Rats can get in through the smallest of gaps.

[Danstable]

I'm probably the least electrically minded person on here, but if your windows worked the opposite way then like already suggested, maybe the terminals were connected up the wrong way round? I guess an electric motor takes reversed polarity (?) better than an intricate piece of electronics....which would probably start belching smoke?!

Just my ten pence worth. Actually, maybe its more like one pence, on second thoughts, was that really worth anything......maybe I owe you money!

EDIT: Just seen the last post, rodents shouldn't be the cause if your car's equiped with a cat....hahahahahahahahahaha!!!!!!!!!!!!!!!!

[Andy_magic]

It does sound like a reversed battery terminal issue.

Lights and motors won't care which way round the battery is, ECU's and alternators will though.

What might have happened is you've smoked the alternator.

[gareth320]

The smoke may appear from under the sill so check round there. If your battery is in the boot (as mine is) power is fed forward to the engine bay etc. If you reversed the poles on the battery you may have connected the +ve to the main earth. This is a major dead short-just think what the cranking amps on a battery is! Thats more than enough to melt wiring, and maybe "confuse"( knacker) other electrical systems. Looks like its inspection lamp time. Sorry.