I have a 1999 BMW 323i. Pretty sure it is an E46. Could be wrong though. This is my first time playing around with a BMW. I just replaced the battery with a new battery, just replaced the alternator with a reman alternator. Started right up, but it was dropping RPMs when it was idling. Almost sounded like the alternator was working too hard but I made sure I got the right alternator with the right amps and everything. Drove it around for like an hour parked it. Came back out about 4-6 hours later. She started up, drove it for like 3 minutes and everything shut down on me while driving on an extension going 45 mph. Went to jump start the battery with brand new copper jumper cables and they started smoking and almost caught on fire. When I put the key in, no electronics turn on, it doesn’t crank at all. I know for a fact that the starter should be fine. It’s not new but it cranked fine and made no weird noises when it did turn over. There was no battery light turning on when I was driving it but every once in a while in the middle of the speedometer a light with a triangle and exclamation point in the middle would come on for a few seconds then turn off. The battery terminals look brand new. No corrosion. I just don’t get it. I can’t try jump starting it because I used two pairs of cables and both of them heat up to the point of smoking. I’m not sure what’s going on here. I knew BMWs have electric issues but I’m dumbfounded on what I should be looking for? Bad grounds? Bad connections? I’m confused man. Lmk