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Rambling Wreck
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Discussion Starter · #1 ·
Has anyone installed an extra 12-volt socket in the trunk of their sedan, coupe, or convertible?
If you have, where did you install it? I'm brainstorming locations for my own installation, but I'd like to see where others have located their sockets and find out how well these locations work in practice.

Here's a good thread showing where Ron Stygar installed a socket in his MZ3 and MZ4 Coupes: http://www.bimmerfest.com/forums/showthread.php?t=25528

Thanks in advance for your replies!
 

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is a Texan
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What do you plan to use it for? Do you have the NAV/Disc Changer area on the drivers side of the trunk? If so, maybe inside the fold down door there or just on the rear facing side of it (much like in the link posted).

Feeling a bit crazy you could always put it up near the badges on the actual trunk lid that show what the car is equipped with (BMW Assist, Phone Prewired, etd).
 

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Rambling Wreck
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Discussion Starter · #3 ·
What do you plan to use it for? Do you have the NAV/Disc Changer area on the drivers side of the trunk?
That's one of the places I'm considering. The socket will be used to power a portable air compressor (for emergency tire inflation only) and for occasional charging of the battery. I'm looking at mounting locations that are reasonably solid and won't be in the way when loading or unloading the trunk.
Feeling a bit crazy you could always put it up near the badges on the actual trunk lid that show what the car is equipped with (BMW Assist, Phone Prewired, etd).
Thanks for the suggestion, but I'd rather keep the wire run as short as possible. Two 12-gauge wires probably wouldn't play well with the small-gauge wires in the bundle that goes from the body to the trunk lid.
 

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is a Texan
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^ Valid point, didn't think of the details before I said it.

Forgive me being nieve, but you plan to put a socket in the trunk, powered by the car battery, only to then plug a charger into it to charge said car battery (or do you mean another battery)?

Seems like the wall of the aforementioned NAV/misc hump would be a sturdy place since it was designed to handle the naturally occuring week rigidity of it being a hump in the first place.
 

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I wired the harness to my battery that comes with the Battery Tender Plus battery charger. I routed it under the tray and out small opening in the back panel in my trunk....just 15 or 18" inches away from the battery. I popped out one of those little square plastic pieces in the back panel..at least they're there on my 330ci and 323i. So that I now have a easy hook up for charging my battery-which can be left hooked up indefinitely with this smart battery tender, and have access to read voltage, with a DVM, or hook up other adapters for 12 volt output.

Take a look at the harnesses provided with this type of charger...ebay is a good place to view it...it will provide you the ability to hook it up to your two battery terminals - under the tightening nuts is where I hooked them up, and give you the connector you need to hook up to the best battery charger made, IMO, and provide you with a cheap, tiny, two prong connector with 12 volt output...you can order extra harnesses from them in order to wire all of your vehcles this way.

You can get the charger and harnesses for $39 to $49 last time I looked. They even sell water proof versions for boats, outdoor mounting etc. they advertise them on the speed channel all the time..two guys garage, etc.
 

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Rambling Wreck
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Discussion Starter · #6 ·
Forgive me being nieve, but you plan to put a socket in the trunk, powered by the car battery, only to then plug a charger into it to charge said car battery (or do you mean another battery)?
The socket will be powered from the battery, and I also would like to plug my Battery Tender into it for charging of the car's battery.

Right now, in order to hook up the Battery Tender in the trunk, I remove the battery cover and attach the Battery Tender clamps to the terminals. The socket would make charging via the trunk a little more convenient in addition to providing a second outlet for running the air compressor.

People who use those 12-volt coolers/refrigerators also would find a trunk-mounted socket handy.

QAfred, thanks for responding. I'll check out the harnesses and that back panel you mentioned. Are you referring to the wide black plastic sill that runs between the tail light bulb holders?
 

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Supporting Member
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Never put on in any of my BMW's but put them in a van and pickup truck with a cab for TV, radio, air compressor, air mattress inflator while camping. I used wire harness protectors I got out of junkyards to keep the wires from getting damaged. I imagine it would be even easier with the battery being in the trunk.
 

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We want the Lion!
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Have not installed it yet, but I bought a Marinco "marine grade" 12V receptacle and male adapter from Parts Express. The plan was to use the bottom slot in the CD changer rack. Also bought a Cobra 700watt invertor and a remote switch plate to add a 110V receptacle next to it.

 

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Rambling Wreck
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Discussion Starter · #9 ·
Have not installed it yet, but I bought a Marinco "marine grade" 12V receptacle and male adapter from Parts Express. The plan was to use the bottom slot in the CD changer rack. Also bought a Cobra 700watt invertor and a remote switch plate to add a 110V receptacle next to it.

I found that receptacle last night. It looks identical to the receptacle in the Blue Sea Systems catalog.

I'm partial to the "factory" look of the BMW outlet mount, but it's bigger and bulkier.
 

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I've installed rear-access 12V plugs in other vehicles, but not in any of my BMWs, yet. It would be handy for a powered cooler/heater as Burdell mentions.

Be very careful in making sure the max loads on the new wiring are in spec, as you don't want to introduce anything flaky to the electrical system on the BMW. And, fire. Did I mention fire?

I also believe there are 2 different amperage alternators available for the E46. Might look into the higher output version, and if your electrical system is designed to handle that.
 

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Rambling Wreck
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Discussion Starter · #11 ·
The air compressor is rated at 14 amps. The wiring will be sized for considerably more. I'd like to keep the wiring from the battery to the socket as short as possible and put a heavy-duty inline fuse close to the battery terminal.

Does anyone know the amp rating of the BMW sockets? The center console cigarette lighter circuit has a 15-amp fuse, so I'm guessing the socket is similarly rated.
 

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Burdell, Have you noticed differences in coating thicknesses in different manufacturers of like gauge wiring? I've installed some 10ga wires, where some stripped the coating easily, and others had a rather thick coating.

Not very scientific, I know...
 

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ROLL TIDE!
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I put one under my center console for my phone (since my normal cig lighter has my push to start button there now). It was easy and cheap. If I was going to put one in the trunk, I'd drill a hole in the panel that covers the battery and mount it there. Right next to the "power", what better place?
 

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Rambling Wreck
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Discussion Starter · #14 · (Edited)
Burdell, Have you noticed differences in coating thicknesses in different manufacturers of like gauge wiring? I've installed some 10ga wires, where some stripped the coating easily, and others had a rather thick coating.

Not very scientific, I know...
It depends on the spec to which the wire was manufactured. For example, SAE specifications list at least three different insulation thicknesses (thin, medium, thick) of XLPE-insulated wire for underhood use.

If I was going to put one in the trunk, I'd drill a hole in the panel that covers the battery and mount it there. Right next to the "power", what better place?
That's one of the locations I'm considering. :thumbup:
 

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The socket will be powered from the battery, and I also would like to plug my Battery Tender into it for charging of the car's battery.

Right now, in order to hook up the Battery Tender in the trunk, I remove the battery cover and attach the Battery Tender clamps to the terminals. The socket would make charging via the trunk a little more convenient in addition to providing a second outlet for running the air compressor.

People who use those 12-volt coolers/refrigerators also would find a trunk-mounted socket handy.

QAfred, thanks for responding. I'll check out the harnesses and that back panel you mentioned. Are you referring to the wide black plastic sill that runs between the tail light bulb holders?
GP, Yes, I am referring to the plastic sill between light assemblies...there is a little one inch square plastic piece that is removable just an inch away from the battery tray...on my two vehicles anyway..makes for a nice place to have the connector I referred to, from the battery tender plus I spoke of, protrude. This harness is already fused, has terminals on it that will fit under your battery terminal retention nuts and the connector you need on the other end to hook up your charger and have 12 volts power when you need it..will take three minutes to hook up.
Check out the Jacksonville link within this e-bay site...has good views of the harness I speak of
http://motors******.ebay.com/i.html..._osacat=10063&bkBtn=&_trksid=p4506.m270.l1313
 

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Rambling Wreck
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Discussion Starter · #16 · (Edited)
Update:

I bought the socket mount parts listed in Ron Stygar's thread and chose to locate it in the right side trunk liner, above the battery. I did so in order to keep the wire run to a minimum. After measuring thrice, I cut a hole in the trunk liner so as to place the socket just above the tilt sensor for the alarm.

Unfortunately, the PDC unit mounting bracket doesn't just accommodate the PDC unit; it also includes an extension that sits just above the tilt sensor. This extension may be intended to hold the control unit for trailer lights if you have a tow hitch. It sits just low enough to make contact with the back of the socket. Not good if I wanted to avoid a short-circuit or keep the wires from rubbing against metal. It's very easy to remove the PDC unit and bracket, so my husband helped me to cut off this unneeded extension.

I ran 10-gauge wires, with heat-shrink insulated 0.25" quick disconnect terminals, to the socket. The wiring diagram is printed right there on the socket cover - the center pin is +12V, and the shell is ground. I attached the positive wire to the M8 stud on the Battery Safety Terminal, with a weather-resistant inline fuse holder and 15A fuse just a couple of inches from the ring terminal. (The cigarette lighter socket in the center console is also fused at 15A.) The ground wire is attached to the same M8 stud where the negative battery cable attaches to the body. Since the wires are located so near the battery, I covered them in 1/4" split convoluted tubing to protect them against damage when it comes time to replace the battery.

The socket works great for charging the battery with my Battery Tender Junior. It'll also be useful if I have to use my portable air compressor, which I now keep tied down along with a first aid kit on top of the battery tray, right below the socket. :thumbup:
 

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cool!
you can also consider an electric cooler in the trunk for long trips, you won't need ice to keep things cool...as long as you have the 120 amp alternator and don't have a GPS, Radar Detector, IPOD etc. all running too...:tsk: like my friend did, and it was tripping her Exclamation Point warning light / and putting her in limp mode...:eek: gotta love our touchy little bimmers, but so sensitive to power fluctuations.
 

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We want the Lion!
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Looks like the same power port on an X5. A pair of them actually.
 

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Rambling Wreck
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Discussion Starter · #19 ·
Looks like the same power port on an X5. A pair of them actually.
Yup. This socket mount is used in a lot of BMWs. The socket and the two plastic pieces that make up the mount cost around $10 to $12 total.
 

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The Boss of Nobody
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What do you plan to use it for? Do you have the NAV/Disc Changer area on the drivers side of the trunk? If so, maybe inside the fold down door there or just on the rear facing side of it (much like in the link posted)..
This is where I would, but since it's a female receptacle you're going to mount I'd do it at the back of the storage shelf. Not visible at all, and you should be able to pull power off the CD changer wiring harness(assuming you're not using it) while keeping the shelf space.
 
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