[Jmlubbe5]

So i recently bought a 2012 335i N55, single owner full BMW history. When i got the car i had to replace the battery since it still had its original battery from 2012. I opted not to do it at the dealer so the battery place put power on the front jump posts and swapped in a battery with the exact specs so it didnt need to be registered (or so they claim) i drove like that for about a month until i got bimmerlink i then registered the batt myself last weekend. I also loaded MHD stage 1 on the car while hooking up the battery to a charger 12a directly to the battery, the following day it went in for a catless downpipe and charge pipe. Fast forward a couple of days i got a message saying: Battery discharged please start engine i then drove the car for a bit and saw the state of charge was around 38% took it to BMW the next day. They claimed it was the alternator and it was only working intermittently. I decided to drive the car for a bit still and take it back to the batt place, they tested the battery said all was good and that on idle there was no current from the alternator. However the battery started charging again as i drove it on a further drive but the message kept coming back now and then. Today on my way home the car died completely, after jump starting it i saw it was charging on idle at about 13v but then the jump points started glowing red in the engine bay..... any ideas? Im new to bmw i have never owned one but this doesnt seem like alternator to me?
Car has 125000kms on the odo. Thanks guys!

[Billfitz]

Whoever told you it didn't have to be registered you should never deal with again. Luckily you probably did it in time. The charger posts getting that hot indicates a serious current draw problem. Make sure every connection to the posts, the battery, the alternator, starter and ground strap is tight. The ground strap may need replacing, they corrode over time.

[Shirazkhan]

1st problem is the battery guys who said it dont need to be registerd,if they believe that then everything they did after that is questionable.But as above do as he says.

[Jmlubbe5]

Originally Posted by Billfitz

Whoever told you it didn't have to be registered you should never deal with again. Luckily you probably did it in time. The charger posts getting that hot indicates a serious current draw problem. Make sure every connection to the posts, the battery, the alternator, starter and ground strap is tight. The ground strap may need replacing, they corrode over time.

Thanks man, turned out to be the alternator cable connected under the positive point at the front, it came loose or perished over time causing a short/arc they cleaned it and tightened it and all is well. Crazy that such a small thing can cause such a big issue.