[Saunders17283]

So I am starting to gather information for a subwoofer/amp upgrade in my MY20 M850xi GC G16.

In the trunk, there is a very elaborate battery setup and I'm wondering if anybody knows if I can use this to tap in for 12V for an added amp.

In the picture, there is a green arrow which points to a 2gauge that I'm fairly confident goes over to the RAM/Booster. Next to it, there are (3) additional blank "ports". Does anybody know the part number for a termination I could use on my 2guage wire to use one of these (3) empty "ports"? See pic. Thanks!

[bloozemanAZ]

Not sure if it helps as it doesn't answer the question regarding the part number needed to plug-into one of the 3 empty slots. That said I'm pretty sure the existing 2guage occupying the used slot is not going straight to the RAM or Booster. Rather they are fed from the power distribution box within the trunk and it looks like that wire is the positive power to it. I spent quite a bit of time trying to Google an OEM or replacement part for that cable but came up dry. If we can find one that may be your best bet along with whatever modification needed on the other end to hook up an additional amp for your subwoofer project.

[Saunders17283]

Originally Posted by bloozemanAZ

Not sure if it helps as it doesn't answer the question regarding the part number needed to plug-into one of the 3 empty slots. That said I'm pretty sure the existing 2guage occupying the used slot is not going straight to the RAM or Booster. Rather they are fed from the power distribution box within the trunk and it looks like that wire is the positive power to it. I spent quite a bit of time trying to Google an OEM or replacement part for that cable but came up dry. If we can find one that may be your best bet along with whatever modification needed on the other end to hook up an additional amp for your subwoofer project.

Holy crap!! That's really useful info! In your third picture, it looks like this shows that power distro fully populated with (4) of (4) slots filled.

Also, on a somewhat unrelated note, new info to me is that I had previously thought we had dual battery setups. One in the front and one in the trunk. Third pic seems to suggest to me that the ONLY battery is in the trunk. It shows a feed from the trunk battery going to the starter/alternator and another feed going to the "jump start" battery post. This would seem to indicate there is no battery under the hood. Correct?

[FBMWWINS]

Apparently these cars do have 2 batteries - the standard AGM battery and an additional lithium ion battery, which is located in the engine compartment near the windshield on the passenger side. The technical documents (see screenshot below) also speak of the two distinct batteries when describing replacement/charging procedures.

[bloozemanAZ]

Originally Posted by FBMWWINS

Apparently these cars do have 2 batteries - the standard AGM battery and an additional lithium ion battery, which is located in the engine compartment near the windshield on the passenger side. The technical documents (see screenshot below) also speak of the two distinct batteries when describing replacement/charging procedures.

Yes, there are indeed two batteries and others have posted in regards in the need to purchase a charger that specifically handles both.

[bloozemanAZ]

Originally Posted by Saunders17283

Holy crap!! That's really useful info! In your third picture, it looks like this shows that power distro fully populated with (4) of (4) slots filled.

Also, on a somewhat unrelated note, new info to me is that I had previously thought we had dual battery setups. One in the front and one in the trunk. Third pic seems to suggest to me that the ONLY battery is in the trunk. It shows a feed from the trunk battery going to the starter/alternator and another feed going to the "jump start" battery post. This would seem to indicate there is no battery under the hood. Correct?

As FBMWWINS pointed out, there are indeed two batteries and each plays its role in the complicated 8-series (along with any other series with all the bells and whistles). I should have added that the images, etc. came from the Technical Training documents posted in a sticky thread. I downloaded them months ago and keep them for handy reference.