12 volt outlet in trunk?

[Craw2theJ]

Is there a way to make the 12 volt outlet in the trunk so it has constant power even with engine off? Any help is greatly appreciated

[M_Bimmer]

Your 12VDC electrical sockets, are powered off of the Terminal 30B power rail, and is relayed controlled by the BDC.

Terminal 30B provides the voltage supply for control units and components that in normal operation are required when the driver is present. For example, terminal 30B will be activated with a status change for a door contact or unlocking, locking or securing the vehicle.

The Body Domain Controller (BDC) is the master control unit for the terminal control. The LIN power distribution box is implemented with an intelligent actuation of different relays and terminals for the rear and front power distribution box. The LIN power distribution box is installed in the rear power distribution box as pluggable separate component.

The BDC control unit activated the LIN power distribution box through the LIN bus. The LIN power distribution box switches on the terminal 30B relay. Terminal 30B is connected with the excitation coil. Terminal 30B relay is applied. This switches terminal 30 to the terminal 30B power distribution box in the front left power distribution box.

The status of the relay is returned to the BDC control unit via LIN bus.

THE FOLLOWING IS NOT RECOMMENDED, but will answer your question.

The trunk socket, X98, is shared with sockets X104 and X105, on Fuse F273.

Your ONLY option would be to follow the red wire on socket X98 over to the wire junction in the trunk (shown below), and remove the wire from the wire bundle node, X1434. Then take the X98 red wire, and connect it directly to the positive terminal on the battery in the trunk.

[Craw2theJ]

Originally Posted by M_Bimmer

Your 12VDC electrical sockets, are powered off of the Terminal 30B power rail, and is relayed controlled by the BDC.

Terminal 30B provides the voltage supply for control units and components that in normal operation are required when the driver is present. For example, terminal 30B will be activated with a status change for a door contact or unlocking, locking or securing the vehicle.

The Body Domain Controller (BDC) is the master control unit for the terminal control. The LIN power distribution box is implemented with an intelligent actuation of different relays and terminals for the rear and front power distribution box. The LIN power distribution box is installed in the rear power distribution box as pluggable separate component.

The BDC control unit activated the LIN power distribution box through the LIN bus. The LIN power distribution box switches on the terminal 30B relay. Terminal 30B is connected with the excitation coil. Terminal 30B relay is applied. This switches terminal 30 to the terminal 30B power distribution box in the front left power distribution box.

The status of the relay is returned to the BDC control unit via LIN bus.

THE FOLLOWING IS NOT RECOMMENDED, but will answer your question.

The trunk socket, X98, is shared with sockets X104 and X105, on Fuse F273.

Your ONLY option would be to follow the red wire on socket X98 over to the wire junction in the trunk (shown below), and remove the wire from the wire bundle node, X1434. Then take the X98 red wire, and connect it directly to the positive terminal on the battery in the trunk.

Thank you for the response and amazing explanation. Do you happen to know if any of the 12 volt outlets have constant power? I had an e38 and the front outlet for the cigarette lighter always had power....which I know is much older technology than the g12.

[M_Bimmer]

Besides the trunk socket (X98) already discussed, which is tied to the two sockets on the rear end of the front center console, for the back seat passengers (X104 & X105), the only other one is in the front ashtray, center console (X17), which is run of a 20A Fuse F50, which is controlled by the Z44_1 Terminal 30B relay, which your USB is ties too as well.

In short, your G12 has no 12VDC socket that doesn't have a relayed battery source. The only way to have direct battery connection is to wire it yourself, which you could just buy a socket from Amazon, like this:

https://www.amazon.com/YCIND-Termina...zcF9hdGY&psc=1

[Craw2theJ]

Thank you so much for the information regarding my questions on the 12 volt outlets in my g12. What I'm trying to accomplish is setting up a way to use the bmw advanced electrical system conditioner to keep the battery charged and doesn't over charge. I had a 2001 e38 that I just plugged the charger straight into the cigarette lighter in the center console and it'd be great if I could use the same charger. What I'm trying to avoid is having to access the battery every time I want to hook it up. I have a fairly thick trunk liner like a weather tech but thicker and then the regular carpet liner and it's not that easy the access the battery. I apologize for bothering you but you seem to have more knowledge than anyone else I know about this issue. The link for the fused female end cigarette lighter with the ring terminal connectors on the other side I can hook up to the battery and have the 12 volt plug accessible somewhere in the trunk? Do you know of any other way I can accomplish my goal of charging the battery that would be the easiest way to set things up?

Thank you in advance for your time and any help you can offer.

[Raimo5]

G11/12 is very different from E38 with its separate electrical buses and relaying system. One of the key components of this system is IBS (Intelligent Battery Sensor) that monitors all incoming and outgoing power from battery(s). It is crucial that this sensor is not bypassed as car is unable to implement proper power management and charging strategy if you do so. You will also end up with errors. That is why the only place where you connect your charger, IF, the battery is connected to vehicle, is terminal posts under the bonnet. That way, all power taken out or put in to the system is clocked by IBS. If battery is disconnected from vehicle's electrical system, then charge it as you will, but you must register battery replacement after that.

This thread has been going under assumption that you want to mount a consumer that is hot wired to battery. If you want to charge the battery, then you must forget about hotwiring something or cigarette lighter sockets. The easiest, most accessible, and only approved way to charge battery on the vehicle is via engine bay terminals.

[M_Bimmer]

Originally Posted by Craw2theJ

Thank you so much for the information regarding my questions on the 12 volt outlets in my g12. What I'm trying to accomplish is setting up a way to use the bmw advanced electrical system conditioner to keep the battery charged and doesn't over charge. I had a 2001 e38 that I just plugged the charger straight into the cigarette lighter in the center console and it'd be great if I could use the same charger. What I'm trying to avoid is having to access the battery every time I want to hook it up. I have a fairly thick trunk liner like a weather tech but thicker and then the regular carpet liner and it's not that easy the access the battery. I apologize for bothering you but you seem to have more knowledge than anyone else I know about this issue. The link for the fused female end cigarette lighter with the ring terminal connectors on the other side I can hook up to the battery and have the 12 volt plug accessible somewhere in the trunk? Do you know of any other way I can accomplish my goal of charging the battery that would be the easiest way to set things up?

Thank you in advance for your time and any help you can offer.

As Raimo5 has stated, you do NOT want to bypass the IBS (intelligent battery sensor).....

If you are like me, my G12, nor are my F85, G07 or 911 for that matter, are not my daily drivers, and they sit in my garage for weeks, if not for months at a time.

I use the battery tender listed below on all my non-daily drivers, which is the same manufacturer of the older BMW branded model (1st link below). BMW has a newer version, which I've provided a 3rd link below (there are several versions offered by BMW). You can use the BMW part number provided in the link and buy it from any BMW dealership, or go to Costco and buy the "Battery Tender" brand for $49 (2nd link below).

Pop the hood and use the terminal posts in the engine compartment, which are the same posts used to jump your vehicle. This is the ONLY place I recommend to use for your battery tender. These posts are "wired" directly to your battery and your starter.

https://www.amazon.com/Battery-Tende...SABEgL1rvD_BwE

https://www.costco.com/battery-tende...100679769.html

https://parts.bramanmotorsbmw.com/oe...SABEgJ80fD_BwE

[Markr]

The BMW charger is made by CTEK (similar to MXS 5.0) and comes with both the crocodile type connector, and a cable you can connect directly to the pos and neg posts under the bonnet (hood), which means that charging or trickle charging is as simple as plugging in the connector.

I purchased another hardwire connector for the other car, and another for the ride on lawnmower, so charging is really simple for all.

[painintheglass]

Battery is right there- you could wire a cig socket right to it, have the wire come out the side of the floor cover. Take you 20 minutes.