Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Convert 12V Outlet to Unswitched ("Always On")

Jughead135

Member
Feb 19, 2020
201
90
Georgia
I'd like to convert the 12V outlet in my 2020 MSLR+ to unswitched (I want it always to have power, regardless of the car "awake" or not).

Does anyone have a hardware and/or software solution for this? Is there a relay I can bypass? (see the TL;DR below for the relevance of that question)

I would ideally like to avoid tapping/pulling wires/drilling holes. The first solution below seemed made-to-order... but apparently only works on pre-2016 cars.

Same question, BTW, for USB power, if that's possible....

=========================================

The TL;DR stuff below is what I've found so far. Prior work is in subdued text (first two bullets); regular text is where (I think) I've found what applies to me, and I'm looking for any help to narrow it down further:


So, that's my research so far. Can anyone confirm "how" the 12V outlet is switched in current cars? Is there a relay I can just bypass? Any other quick-and-dirty solutions that don't involve drilling holes in my brand new car?

If I can't get anywhere with this, I assume the next least-invasive way to do it is to find an unswitched 12V source in the center panel (behind both kick panels, I believe?), tap into that, run a wire to the back of the center console, and swap the existing +12V (switched) wire on the outlet for this new +12V (unswitched) wire (and hope it's got an appropriately-sized fuse on it??). I can't believe this hasn't been done already, though--I just need someone smarter than me to point me in the right direction.... Please! :D
 
  • Informative
Reactions: rickyjb

Akikiki

A'-Lo-HA ! y'all
Nov 26, 2012
6,436
4,526
Kaneohe, HI
Do not credit me. I just saved this info from another post here - from a galaxy far far away...
Converting console power
Converting console power to always on

BTW, it's a simple matter to keep the 12v outlet in the console live all the time if desired. It's just a simple relay in fuse box #2 (the one on the passenger side under the removable cowling cover - see owner’s manual). Simply make up a jumper consisting of short piece of 14AWG or better wire with a couple of male 1/4" spade terminals.

Pull the front most passenger side relay out and insert the jumper into the now exposed 1/4" female receptacles, and you're done, the 12v outlet is now on all the time. You can quickly change it back anytime by removing the jumper and reinstalling the relay.
Converting console power.jpg
 

Jughead135

Member
Feb 19, 2020
201
90
Georgia
Do not credit me. I just saved this info from another post here - from a galaxy far far away...

That’s the first post I cited above, by @Ingineer . It’s a different fuse panel than I have in my car. I’ve been unable to identify a similar relay in mine—that’s what I need to figure out. IS there such a relay in my car? And, if so, WHERE is it?
 

TravelFree

Member
Mar 23, 2020
727
672
Jacksonville, Florida
If I can't get anywhere with this, I assume the next least-invasive way to do it is to find an unswitched 12V source in the center panel (behind both kick panels, I believe?), tap into that, run a wire to the back of the center console, and swap the existing +12V (switched) wire on the outlet for this new +12V (unswitched) wire (and hope it's got an appropriately-sized fuse on it??). I can't believe this hasn't been done already, though--I just need someone smarter than me to point me in the right direction.... Please! :D

Some info on my own research into this that may help you:
1. I have read that getting to the back of the 12v receptacle in the 2020 MS is very difficult; lots of disassembly.
2. Any 12V source you wish to tape into may not be high enough current capacity for a general purpose 12 volt device.
3. An approach I have been considering is adding a second 12V receptacle that taps into the 12V motor power on the rear trunk lift which is live when the car is off. It may only over power it's fuse when powering the accessory and you try to open the trunk at the same time. But finding this wire is in the harness under the side cover on the passenger side of the Trunk. Supposed to be the fat red wire you tap into.
4. I found one owner added a 12v tap on the battery + connector with an inline fuse, feeding the wire through the firewall near the battery. There is a rubber cover on an existing hole he used. This was going to be my approach if I ever add one. It seemed to be the easiest by running the wire under the carpet to the back seat where I needed it and mount a receptacle with an L bracket off the center console.
I have not verified any of the above but is the extent of my research to date. My plan is to supply 12 v to a small chiller for food and snacks on a road trip. In other cars, this worked fine on a switched outlet so I may just continue to use the existing receptacle.
 

TravelFree

Member
Mar 23, 2020
727
672
Jacksonville, Florida
Update to my 12v outlet project:
I completed adding a trunk single outlet using the 12v switched wire that feeds the audio amplifier. I added a fuse to the line for 15 amps. Sorry, I didn't take pictures of this behind the scenes wires selected but in my Tesla it is a heavy red gray wire feeding the audio amp connector.

I added a dual 12v receptacle to the rear seat center console by tapping into the wire feeding the existing 12v console outlet. I fused this for 7.5 amps because it will only be used for my chiller cooler which is rated for 4.6 amps.

After many attempts to tap the main 12v battery in the frunk, I decided it was too difficult to feed the wires through the firewall. None of the feed through holes shown on many You Tube videos worked for my MS2020 version car.

I decided to use switched 12v because I don't trust myself to unplug a device when leaving the car and I don't want this to drain the battery. For those wishing to access low current 12v always on, there is an easy way by tapping into the OBDII connection, However this also feeds the glove box light all on a 5 amp very hard to get to fuse. So whatever you use on this method would have to be a very low powered accessory. You can buy an easy adapter from Amazon that plugs into the connection and is probably the simplest solution but it is low current only.

https://www.amazon.com/gp/product/B002BHX1X8/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

IMG_1816.jpg IMG_1817.jpg IMG_1820.jpg IMG_1822.jpg
 
Last edited:

Akikiki

A'-Lo-HA ! y'all
Nov 26, 2012
6,436
4,526
Kaneohe, HI
Just so you folks know, in another thread here under Model S, I have a posting that explains how and the source for accessing always on/persistent 12V in the trunk. It explains how I tapped with a large gauge wire feeding a 4 post/fuse box and mounting the box. Now I have 4 easy to access/connect 12V power sources. I used one for my rear mounted main and side window mounted Blackvue 2CH dashcam.

If I find the thread/post, I will add it here. I used info from the instructions (as I recall, page 17) when I installed the Lighted Rear Applique which I think is still available at tesla-lights.net (Which by the way, is a fun and great product.)
 

Kurtbe

Turning a 2017 S into a 3*** Hotel
Jun 19, 2019
59
19
Ghent/Belgium
Hi Akikiki, I looked for the thread you talk about, but could not find it. If you could point me there...
I am looking for the 12V socket to be "always on" in my 2017 Model S. Or another permanent 12 V supply of at least 10Amps. If anyone has a solution, I'd love to hear it!
Thanks beforehand, Kurt
 

Akikiki

A'-Lo-HA ! y'all
Nov 26, 2012
6,436
4,526
Kaneohe, HI
The Tesla-lights.net installation instructions had a section on about page 17 to tap into power from the liftgate for persistent power in the trunk.

This is old, but I think it still works. Collected it from a thread years ago on TMC
Converting console power to always on

BTW, it's a simple matter to keep the 12v outlet in the console live all
the time if desired. It's just a simple relay in fuse box #2 (the one on
the passenger side under the removable cowling cover - see owner’s
manual). Simply make up a jumper consisting of short piece of 14AWG
or better wire with a couple of male 1/4" spade terminals.

Pull the front most passenger side relay out and insert the jumper into
the now exposed 1/4" female receptacles, and you're done, the 12v
outlet is now on all the time. You can quickly change it back anytime
by removing the jumper and reinstalling the relay.

Frunk fuse 12V jumper.jpg

Frunk fuse 12v jumper 2.jpg

Liftgate controller 2.PNG
Liftgate Controller 1.jpg
 

Attachments

  • Spare 12V Power Circuit - 09 16.pdf
    1.1 MB · Views: 26
  • Informative
Reactions: Curb71

Kurtbe

Turning a 2017 S into a 3*** Hotel
Jun 19, 2019
59
19
Ghent/Belgium
The Tesla-lights.net installation instructions had a section on about page 17 to tap into power from

Thank you for the reply Akikiki. Corona months later I picked this up again. Unfortunately your solution does not work for my car. The bypass of the relay you post is no longer valid for +2016 cars.
So far I found a solution via the ODB2 connector. I changed the fuse from 5 to 10 Amps. The cables should hold that. I should be able to test run one of these days.
 

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top