Is it possible to control power on 12V outlet?

Sep 6, 2021 | 12:18 AM

todesto

Thread Starter

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Joined: Sep 2007

Posts: 9

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ML320

Is it possible to control power on 12V outlet?

Hi, all
I have 2001 ML320 and there is 12V outlet under glove compartment.
It's supplying voltage all the time and I want to know if it's possible to relay the power so that it supplies power when engine is on and off and turned off.

The reason why I ask is, I have dashcam that I'd like to connect the power to that but it's supplying power all the time so that it actually drained my car battery one time.

Is it possible?

thanks in advance.

Sep 6, 2021 | 04:39 PM

Bezalel

Junior Member

Joined: Oct 2013

Posts: 69

Likes: 11

From: Sedbergh, England

ML320 W163 2000

Quote:

Originally Posted by todesto

I find it very useful to have the 12V power outlet live all the time as I have a mystery electrical short somewhere and so I trickle charge the battery with a 20W 12V solar panel plugged into that socket and it will charge the car up from dead flat just with the solar panel (if you leave it long enough...)
I guess you could unscrew the panel that the 12V socket is in, as you do when changing the cabin pollen filter, and a bit of simple wiring could connect it to a separate switch. I wouldn't know precisely where you would wire into the ignition but it wouldn't be that difficult, I am sure, as it is only about two feet away.
However, the simplest zero cost solution is to unplug the dashcam when you don't want it on... Alternatively, if you measured the current drain from the dashcam, then you could counter it with a solar panel on the roof, or wire the dashcam straight into the electrics elsewhere so it was only on when you turned the car on, keeping the 12V socket free, or plug it into the 12V socket in the centre console ashtray, which is only live when the ignition is on.
I don't know why all modern cars don't have a solar panel on the roof as you could easily fit 100W unobtrusively and then the car could be even cleverer and do all sorts of things while parked up...

Nov 5, 2025 | 08:03 AM

OldManAndHisCar

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Joined: Jun 2021

Posts: 3,110

Likes: 1,346

From: Fleriduh

W212 E63S Wagon - GSL580 - E63 - E350 - C300

Quote:

Originally Posted by Bezalel

I don't know why all modern cars don't have a solar panel on the roof as you could easily fit 100W unobtrusively and then the car could be even cleverer and do all sorts of things while parked up...

I know why, it would raise the price, complexity, TCO and cost to insure. Somehow we have made it eons with out it.....(that said, I do have them on my RV, they are the #1 most failed compenent on that vechild by a large margin)

Nov 5, 2025 | 08:49 AM

streborx

MBWorld Fanatic!

Joined: Oct 2019

Posts: 5,152

Likes: 1,766

From: Colorado

G550

Quote:

Originally Posted by todesto

Your 12v socket is fused somewhere at a fuse block. Locate the fuse, and then check the other fuses to see if there are other circuits that are ignition switch controlled. If you do find that there's a switched set of fuses, you could make a jumper with an inline fuse to connect between the switched 12v source and the 12v socket connection. You might get lucky and find some empty fuse sockets that could make the hack easier. I recently discovered that my Jeep Wrangler's 12v socket fuse can be positioned in either a switched or non-switched location -- something German engineers haven't yet thought of.

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