12V to female USB - safe to wire up?

[joeysnowey]

Hi all, re my R320 ....

I want a USB socket or probably 2 of them. One for my dash mounted iPhone holder so it charges automatically, and one for Anker bluetooth to aux in audio adapter I bought based on recommendations of users on the forum. The 12v socket in the cockpit is a pain because you have to have the lid open to have anything plugged into it. There is another behind the centre arm rest console, but that is likely to get kicked by rear passengers, so I want to do what I did in other cars in the past, namely to pull out the ashtray unit, get to the wires behind the 12v socket, and solder in a red and black lead to a female USB socket somewhere convenient maybe in the glovebox or maybe actually surface mounted under the footwell or somewhere else handy. My main question before proceeding is whether this will mess with the car's diagnostics, voltage detectors etc etc? Anyone have any tips for wiring up an extra USB socket or two?
thanks

 

[DelDrew]

I have done this in my 2007 clk and had no problems. Mine runs a Bluetooth audio unit that plugs into the aux 3.5 jack in the glovebox, a hard wired iPhone powered cradle and a dashcam. I have an inline fuse and power switch between the 12v supply and the USB socket. All works fine for me


Sent from my iPhone using Tapatalk Pro

 

[garycat]

I've done similar, I used crimp bullet connectors to tap into the wires going to the 12v socket and ran a lead to a trailing female 12v socket which I fixed above the glovebox so it was out of the way. That has a twin USB adaptor plugged into it that powers my phone charge and dashcam.

All works fine with no errors or burning smells.

 

[BTB 500]

I want to do what I did in other cars in the past, namely to pull out the ashtray unit, get to the wires behind the 12v socket, and solder in a red and black lead to a female USB socket

I guess you mean some kind of adapter that converts the 12V+ input to 5V, rather than a plain USB socket?!

 

[brucemillar]

Just buy a Piggy Back blade fuse adapter then use any switched live fuse you choose and solder a USB expander box onto the piggy back lead. I did this with my Dash Cam using a switched live in the under bonnet fuse box. There is nice big grommet behind that to let the main loom into the car, just above the accelerator pedal (on most cars)

 

[Dec]

One of the USB's in the link, and it from the back of the cigar lighter as you suggest, it wont cause any problems.

See… 12vc usb socket - Google Search


Dec

 

[chrisk2010]

Just buy a Piggy Back blade fuse adapter then use any switched live fuse you choose and solder a USB expander box onto the piggy back lead. I did this with my Dash Cam using a switched live in the under bonnet fuse box. There is nice big grommet behind that to let the main loom into the car, just above the accelerator pedal (on most cars)

Thanks Bruce and OP for posting. I was looking at exactly that last night for a dash cam and was going to ask the question today if anyone had done it

Something like this https://www.amazon.co.uk/dp/B01K4SK642/?tag=amazon0e9db-21 or https://www.amazon.co.uk/dp/B00XHYSQAC/?tag=amazon0e9db-21 i realise it's 1.5amp on that one but others are around.

 

[garycat]

Incidentally I tried one of these - https://www.amazon.co.uk/dp/B00GXXFBC0/?tag=amazon0e9db-21

But it interfered badly with by DAB reception so changed to a female 12v accessory socket and fixed a good quality twin USB adaptor into it. This one I think - https://www.amazon.co.uk/dp/B00Q2GFP4M/?tag=amazon0e9db-21

 

[brucemillar]

On my W203 I opened the front engine bay fuse box and looked for the main loom entry point. I then poked a long thin rod (it is garden plant stick) down the loom, got inside the car with a torch and there it was above the accelerator pedal. Taped the camera wire onto end of he stick (inside the car) and pulled it back up from the fusebox end. Total time about 5 minutes and a stiff neck. You can use crimps too attach to the piggy back fuse, but I prefer solder and heat shrink. Over the years I have become anal about crimps failing.

 

[richard]

Make sure you use a fuse between the 15A cigarette lighter feed and those thin wires. For the adapter above 5 Amp looks about right. 5V@3Amps is 1.25 Amps at 12V if the adapter was 100% efficient which it is not.

Richard

 

[joeysnowey]

Fantastic replies thanks everyone. Various approaches suggested there. Not sure I fancy digging into the fuse box, although those piggy back things look brilliant! Depends which is easier to get at on the R320, the fuse box or the back of the 12v lighter socket in centre console. Will have a fiddle but thanks again for such useful replies.
I haven't got a dash cam but really want one when I can afford it, so many terrible drivers where I live, and I mean TERRIBLE! (Yes, I am suggesting there are areas of the country with better and worse drivers. Perhaps an extension of average IQ, I don't know ). I have lived all over the country including Ireland, and never have I seen people who indicate right at every roundabout unless they are turning left. In other words "my right indicator means I am NOT going LEFT" - WTF?!

 

[joeysnowey]

PS - I think I will probably wire straight off the back of the 12v socket, using one of these https://www.amazon.co.uk/dp/B00GXXFBC0/?tag=amazon0e9db-21

if I do that, is it a good idea to install an inline 3amp blade fuse on the red lead?

 

[richard]

PS - I think I will probably wire straight off the back of the 12v socket, using one of these https://www.amazon.co.uk/dp/B00GXXFBC0/?tag=amazon0e9db-21

if I do that, is it a good idea to install an inline 3amp blade fuse on the red lead?

Yes. The fuse protects the wiring after the fuse etc which won't take 15Amps which is what the socket is fused at (and thus will melt / catch fire if the wrong conditions occur).

R

 

[joeysnowey]

Thanks Richard, so in that case probably best to use a bit of heavy 20A+ cable to the fuse, then can drop it down after fuse. sound sensible?! Can you tell I am no sparky?

 

[m80]

I would use a slightly higher rated fuse to avoid nuisance popping, say 5 or 6 amp.
I would also tune the FM in to a weak station and connect the device to a 12v supply in the cabin to test for any RF interference. Some of the lesser quality electronic devices produce radio interference and once 'permanently' installed is more of a nuisance.

 

[joeysnowey]

Handy to know thanks