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12 v auxiliary power tap AND adventures taking apart the center console

Sometimes you need a 12V power feed for a piece of after market equipment. Getting one was quite an adventure. In the end, it didnt have to be so difficult, but hindsight is always 20-20.

First I asked Washington D.C. service. They were very non-comittal, citing advice from their lawyers (weak excuse). I wanted a switched 12v source, that would turn off when the car turns off. Turns out, the 12v cigarette lighter plug in the Model S does switch off when the car powers down. That's good. So I figured I would get 12V from the back of the cigarette lighter plug, as I needed it near the center console anyway.

NOT SO FAST! I set about taking apart the trim on the center console. The carpet on the bottom is simply pried out, attached by a novel kind of velcro. There are 2 bolts that secure the plastic remaining to ... something. I loosened both bolts but it wasnt clear what was now free to move. You can snap off the leather trip that lines the center console. There is a "cap" on each side that simply pulls off by pulling up. Easy. The sides also are on clips; snap of by pulling to each side (outwards). That does give you access to part of the guts of the center console. But not near the lighter. THere's a plastic piece on the center console that is immediately above the rear end of the carpeted area; it faces the front of the car. I figured that would give me access to the lighter. The top rim snaps off, after you remove the leather trim from the sides of the main part of the center console (the part with the cup holders in it). They, too, snap out to each side; it is easiest if the seats are in the farthest forward positions. After removing the sides of the main part of the center console, the top edge of the piece of plastic I referred to above (immediately above the rear end of the carpeted area) snaps out with clips. I figured the bottom would snap off with clips too, but try as I might, no luck. Turns out there are two screws that secure the bottom of that piece of plastic from the back.

So, remove the rear passenger vents (simple clip release on one side; the whole thing comes out). You are left with a plastic duct that comes up from the floor to feed the vent you just removed. The screws you need to loosen are behind that duct. There is NO WAY to get that duct out! I think it must have been grown from embryonic duct cells in place in California. There are 4 plastic retainers that secure the duct to the sides of the center console. Removing those does ... nothing. You can not slip the duct out, so it is really difficult to get to the screws that are behind it. Eventually I was able to bend the duct slightly (pliable plastic) and slip my torx screwdriver behind it to loosen the two screws, and VOILA, the plastic piece on the front of main part of the center console falls off.

Did that allow me to get to the wires feeding the cigarette lighter? NO! I could reach the wires with my fingers, but I could not get access to them to tap into them.

Plan B:

Go to the fuse box. You remove the "service" panel which is the plastic cowling at the back of the frunk, abutting the windshield. Snap it up from the windshield edge, then pull it back towards the windshield. You need access here anyway if you ever want to check fuses, or check brake fluid. There are two accessible fuse boxes (and one that is not so accessible). The key for the fuses is in the Owners Quick Guide. I chose the fuse that is for the "12v power socket." This is a 15A fuse.

You have to remove the back of the fuse box. To do this, remove the fuse box with 2 10mm bolts; turn it upside down. There are 4 clips that hold on the back (bottom) of the fuse box. Release them with a small flat screwdriver inserted from the TOP side of the fuse box. I wish there was a way to "disconnect the negative terminal of the battery" like you do on all ICE cars when doing any electrical service. You can turn the car off from the touch screen, but it automatically turns itself on again at random intervals (annoying); even with it turned off you have not de-powered the whole car. So just BE CAREFUL. (If someone knows how to truly power down the whole car for service, please tell me!). The fuse in question is FED with a large white wire, and the output of the fuse is a smaller white/black wire. It is fuse F35 (see diagram on page 27 of your manual) You want to tap into the smaller white/black wire that you can see attaches to the fuse in question. Remove the fuse first. Carefully strip 1/8" of insulation, attach your wire, and tape it carefully. When done, make sure the end of the wire you just attached is not contacting anything important, then replace the fuse. Now you should be able to measure 12V (or maybe 13V) between that wire and ground when the car is on, and 0 (or a few mV) when the car is off.

For the ground, I simply attached a fitting to the bolt that secures the lift for the frunk.

What an adventure!

Let me know if you have any additional tips! (but my work is done...)

Great write up, but a little difficult to follow which bits of the center console you referred to. Don't suppose you took any pictures?

And after you tapped the fuse box, how did you get the wire back into the cabin?

Thanks for documenting your valiant effort to jailbreak 12V power. Glad you didn't blow anything up! The perfect storm is when you get an inadvertent short. 15 amps will melt the jacket on one wire and can take down neighboring circuits. (A defect caused such a failure in my MB SL and it cost Mercedes $15K to fix the chain reaction damage.)

The definitive guide would be a video post. This sounds nontrivial, and strictly for hardcore DIY buffs.

I havent put it all back together again (in the passenger compartment) so I will take pictures tomorrow.
Good question about how to get the wire to the cabin:

In the frunk:
Remove all 4 plastic trim pieces that surround the frunk. The first to be removed is closest to the windshield; it is removed to expose the master cylinder etc. Remove this by pulling up on the edge closest to the windshield to remove the clips; then rotate the whole rear most edge of the plastic piece upwards and slip it out from under the rubber gasket that seals the frunk (this is the same service panel that is referred to in my first post). Next to go are the two plastic panels over the fenders: unscrew the single round rubber knob, one on each side (these knobs are attached to studs underneath; just unscrew the knob). Then snap out the plastic cover over the right fender and over the left fender. Once these 3 pieces have been removed, if you need to (to get behind the nose cone, to get to the steel bumper, etc) you can remove the front piece of black plastic cover ... this is the one with the chrome piece in the middle that surrounds the frunk latch.

Remove the frunk floor carpet. Remove the 4 rubber/plastic knobs (2 on each side) that are immediately to the right and left of the deepest extension of the frunk (they look like large knobs). Peel back the carpet from the right and left sides of the long boxy extension (the boxy extension is the box shaped extension of the frunk that goes from the main part of the frunk back towards the passenger compartment). Then you will see a bunch of 10mm bolts (perhaps 8 or 10); remove those and the plastic box shaped extension of the frunk can be removed.

Now you have a pretty good view of the guts of the car in front of the windshield. On the passenger side you will see a 12v battery. You will see the shock towers on both right and left side. etc.

You will note a 3/4" diameter rubber hose exiting the firewall right in the middle, and mysteriously turning downwards to drip onto the main battery area. This is some sort of condensate line for the heating/cooling; it drips water periodically. STrange location for it. I routed wires from the frunk through the rubber gasket that surrounds this 3/4" hose. To do this, first remove the hose end from the zip-tie that holds it against the firewall (do this carefully and you can replace it back into the zip tie without removing the zip tie .... this is significant because it is a special zip tie that is secured to the firewall). Then I took a small pair of needle nose pliers and put a bunch of lube grease on the jaws. Then I was able to push these lubricated jaws through the rubber gasket, between inner diameter of the gasket and the 3/4" hose. Once I established a passage, I pushed through my wired on the needlenose pliers.

If you have taken apart the side front panels of the center console as I described in my initial post, you will see the origin of this 3/4" hose in the passenger compartment. Look around this hose for whatever you push through from the frunk. Good luck!

You asked if I took any pictures: I dont see how to attach pictures in this thread?!

Thanks again for the details. For pictures, you should upload the pictures to fickr, imageshack.us or your favorite hosting site, then copy the 'share' code that starts with <a href=... or <img src=...

If the code already includes a "width=" item, change the number to be 600 to make it fit here; also delete the height="..." bit so that the picture retains its aspect ratio. If it doesn't, find the bit of the code that starts with <img src=... and find the > sign. Add width="600" just before it.

You should be good to go.

Stephen1
Planning on adding a rear inverter for 110 plug/USB power this weekend. Really appreciate your detailed descriptions but your pics would be priceless as an aid. Any chance you can email them to me at nkohlimd@hotmail.com. Much appreciated.

I too need to follow these steps, which you've done an amazing job of describing.

Can you please email me photos as well...moemistry@gmail.com

Thanks!!

Please send me pics too. I want to add an inverter (a big one) and not sure where to begin. bryan@mendotaelectric.com

I plan on installing a three LED light strip in the rear of my center console insert. The map lights do not shine any light into the console. I will tap into the "cigerette" lighter/accessory socket for switched 12v power, if I need to I will add a switch but I am fairly sure that the lighter plug turns off when the car "turns off". If there is any interest in this project I will do a seperate post/write-up.

@AirForce462 - I have the same plan in the works, but still awaiting the console. When I get it and do the project I'll write it up in our modifications section. The lighter connection is a good way to go as it goes dead when the car is "off".

@nkohlimd writes: "Planning on adding a rear inverter for 110 plug/USB power this weekend."

I don't understand. The Model S includes two powered USB ports, so there's no need for an inverter to power USB devices. Granted they are not switched on and off with the car, but a USB car charger like this one could give you two additional USB power ports that will turn off when the car turns off. Using an inverter would be a big waste if all you need is USB to charge a phone or tablet.

If you need AC power for something else like a laptop computer, just plug the inverter into the 12V socket. But if it needs more than 180 watts (15A * 12V) you will blow the 15A fuse. Note that a big laptop power supply, such as the "170W" model needed for a Lenovo ThinkPad W530 or similar, would overload that outlet when used with an inverter.

@Stephen1: How much power does your "after market device" need? I wouldn't try to draw more than 180W from the 12V system in the Model S no matter how you homebrew a hookup, unless it is used only briefly. Otherwise, the DC-to-DC converter in the Model S may not be able to pump enough energy into the 12V battery to keep it charged. If you drain your 12V battery too much, the car will simply shut down, even if there's plenty of charge left in the main battery pack. Everything in the main cabin (seat heaters, displays, computers, lights, radio, USB ports), plus the critical 400V DC switching relays, gets power from the 12V system, not the main battery. That 12V battery can only get recharged from the 400V system at a somewhat limited rate, due to the design of the DC-to-DC converter, according to various posts I've seen. Maybe someone knows where to find the specifics about that.

If all you need is an extra DC outlet, why not use a DC splitter like this one?

The last "this one" was supposed to be a hotlink to

http://www.amazon.com/adapter-cigarette-lighter-splitter-MRS152UV/dp/B00...

but I must have messed up somehow.

Nice!

I had a radar detector hardwired and they found the cigarette lighter wire under the passenger side of the center raceway. That trim comes off easy i believe and then they tapped it behind the cubby - which needs to be removed for tapping. Installer said it was easy. Now having your own dedicated 'always on' line, that's another story.

I really think Tesla should provide 12V outlets in the front and back. One set that is always on and another set active when the car is on. People are increasingly going to need access to power and I think everyone is far better off if Tesla would provide the power outlets than force their customers to take apart panels looking for power sources.

It should not be that difficult to get power for a dash cam or radar/laser detector sensor, in the front or the back.


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