Ditto above...only trickle charge or jump from the dedicated positive & negative points in the engine bay designed for this purpose. If you connect directly to the battery post while it is still installed...you bypass the IBS (intelligent battery sensor). If the IBS picks up “undetermined” changes to the battery’s power...it can incorrectly interpret those changes as an issue...and you could then start to get warnings from the check control system. So to avoid this...jump or charge from the engine bay terminals only. If you don’t know exactly where the
negative & positive jump terminals are located...they should be pointed out in the owners manual. Not everything in the engine bay that you think is grounded...is grounded...so to avoid not truly connecting to ground...use the dedicated negative jump terminal. Sometimes the negative jump terminal is a dedicated hex bolt and sometimes it’s just a small metal pin. My 2013 6 series has a simple metal pin...my 2014 X5 has a hex bolt.
Info from the BMW TIS: