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Power socket - Negative Earth


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Hi all

I am thinking about installing a twin power socket and usb to my Negative earth TR4 and could do with some advice on the wiring.

The power socket is pictured and I would like to hard wire it. The male plug contains an 8w fuse and I assume it would be sensible to have a similar fuse in line.

There is a radio installed between the switchgear and the gearbox tunnel (This has a usb socket but I have no idea whether this is used to charge a phone or to play mp3s from a usb stick!)

My intention was to connect into the power supply and earth for the radio. Is this the best way forward? I do not have a multi fuse box under the bonnet (just the original unit)

Andy

IMG_0447.JPG

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Hi Andy,

one would assume that the connector plug is a straight forward 12V connection.

However rather than simply cutting it off  -  open it up to make sure there is are electronics inside to drop the volts to 5V. 

SatNavs etc have the same plug but reduce the volts to 5V and are terminated in a micro USB plug.

If you are happy it is a simple 12V plug then ascertain which wire goes to the plug centre pin - this should be positive (+Ve).   Either switched or permanent live - your choice.

Connect this to a decent 12V supply via an inline fuse.  Connect the other wire in the plug to earth

The USB socket on the radio is to plug your stick into to play music. I'm sure it is not a charger in any way. 

 

Roger

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6 minutes ago, RogerH said:

Hi Andy,

one would assume that the connector plug is a straight forward 12V connection.

However rather than simply cutting it off  -  open it up to make sure there is are electronics inside to drop the volts to 5V. 

SatNavs etc have the same plug but reduce the volts to 5V and are terminated in a micro USB plug.

If you are happy it is a simple 12V plug then ascertain which wire goes to the plug centre pin - this should be positive (+Ve).   Either switched or permanent live - your choice.

Connect this to a decent 12V supply via an inline fuse.  Connect the other wire in the plug to earth

The USB socket on the radio is to plug your stick into to play music. I'm sure it is not a charger in any way. 

 

Roger

Thanks Roger

I have used this in my daily driver for my SatNav and it was fine (My SatNav has a cigar male plug at one end and a micro usb on the body of the SatNav itself).

There are no 'electronics' in the male plug of the unit in the pic, just a fuse. There is a red +ve wire to the plug centre.

 I thought that was probably the case with the radio usb.

Andy

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Andy

Can I throw a spanner in here............don't do it !  The cabin space is already limited and your bit of kit is huge and complicated and very easy to catch with a knee or two (sorry)

Could I recommend a single socket, in line fused, 12v, very easy, snug to the H frame. out of the way. Then think about what you need plugged in. Sat Nav and .........maybe a phone charger, two feeds,  1x USB, 1 x C Type (2019 onwards phone). Plug in a twin socket, 5V step down adapter,  Sat Nav &  phone sorted. Remember phones are all going over to C Type charge leads and you normally plug that into a car charger and then plug THAT into a socket, cut out the middle man. Lots of adapters on the market, if your phone is still the older USB lead then simply buy a twin USB adapter. Need a conventional 12 v socket because somebody still has an 'old tech' charger, pull out the adapter, and you still have a 12v socket................just an alternative with modern tech. I've done overnight navigations, Potty, Nav, two phones. They rarely all need to be plugged in at the same time. Maybe a different way to go ?

NB EXAMPLE ONLY, WIRED TO MATCH LOAD AS REQUIRED. CHECK ADAPTER MEETS YOUR NEEDS

  

Socket 2.jpg

Socket.jpg

 

Edited by North London Mike
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Ocheye,

one of these is much more compact (the pic is merely an illustration, many different versions available)

image.png.2352db1e513b7dc29f32697b476a2726.png

 

Sure, it only gives you USB ports, but a voltmeter as well!     And I'll bet you can find a lead with USBs on both ends to run your satnav.

John

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Andy

I have used the same unit in my 20 year old Boxster for many years when I need to power a sat nav + perhaps power a phone. Attaches using velcro under the dash so removed when not needed.

In my 3A I have the following under the glove box (must be more room than in a 4 as never been knocked). Twin USB outlets on the left and a single standard outlet on the right.

Just checked the wiring though and no inline fuse :(. What size is recommended?

Miles

Version 2.jpg

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27 minutes ago, MilesA said:

Just checked the wiring though and no inline fuse :(. What size is recommended?

 

It depends on what you are going to power. If it is just a phone and/or sat-nav then 10A is more than adequate and you might even go lower.  If you are going to use the power socket for something like an electric jack for instance, then 25A is more appropriate provided the wire size is sufficient. 

Edited by RobH
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2 hours ago, john.r.davies said:

Sure, it only gives you USB ports, but a voltmeter as well!     And I'll bet you can find a lead with USBs on both ends to run your satnav.

John

Unfortunately my SatNav can only plug into a cigarette lighter socket. My phone, however, uses usb

Andy

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Thanks North London Mike. I'm afraid I only understood part of what you posted.

If I only have a single 'cigar lighter' type socket, I would then need to use my double in order to power my SatNav and phone at the same time. I have a double usb converter in my daily driver and it is a pain because I can't run my SatNav at the same time as charging the phone which is how I came by the combination unit that I have pictured. My iPhone uses usb and I won't be upgrading for some time as it is only one year old.

Andy

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3 hours ago, john.r.davies said:

Ocheye,

one of these is much more compact (the pic is merely an illustration, many different versions available)

   And I'll bet you can find a lead with USBs on both ends to run your satnav.

John

Apparently not, John. It is a Garmin and they have told me I can't convert to usb

Andy

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Some of the Garmin charge cables function as an antenna for the traffic data. Using a non-approved cable simply disables the traffic data, however the traffic data may obtained in this way may be rendered irrelevant if you use the Garmin app on your phone which gives more complete data.

If you can plug your Garmin into your PC and it charges you can use a standard cable plugged into a car usb charger.

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Hi Ocheye

Like others I'm surprised that you can't convert your Garmin to USB (just how old is it :huh:)

So, thats why I chose to retain my 12v socket, good for a fall back. Your Garmin will have an internal battery, good for 60+ mins and your phone should be good to go all day. So, again, you seldom have to charge both, maybe on a 2nd day, but unless camping or on a night rally, you'll have charged your phone overnight. I carried a double adapter for a couple of years to solve just your problem, until I realised I hadn't really needed it. So a temp fix, when you upgrade your Nav to USB you won't need it. Remember whatever you engineer into your car now will far out live your current tech, future proof it now........

Socket 3.jpg

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I have the same Garmin GPS

 I use it in 3 of my cars, and only have the original charger in one of them. I use a generic mini USB charger in the other two cars. Never had a problem.

I also charge it at home from a 13A skt with built in USB outlet.

Bob

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USB is a Universal Serial Bus.

It has four wires two of which are the serial bus, and the other two provide +5Volt supply and ground. USB sockets may be rated for 1 Amp or 2.1Amp.

The serial bus is relevant when plugging it into a computer, otherwise it is a charging cable. There is no magic involved.

If you want +12 Volts, most people will go for the Cigarette lighter format of connector. There are other smaller and more useful options, but will require normally changing the plugs on the device to suit.

The cigarette lighter connector was never designed as a power supply outlet and has been hijacked to be so due to lack of any other "standard" outlet. In my view, it is totally unsuited to the task for which it has been hijacked.

TT

Edited by tthomson
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There may be no magic involved in USB but there are quirks. A few manufacturers (luckily only a few) make non-standard connections which means that normal USB cables will not work with their equipment. I have encountered a couple of those though not recently. I believe one had put a resistor between the serial connections in the cable. The kit sensed that and would not work without it so you had to have their own cable.  

The other had done a similar trick with the charger unit so you couldn't charge the kit from anything else, even though the USB connection looked standard.  Sneaky.

Edited by RobH
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It just worried me when they say "The provided vehicle power cable must be used in the vehicle in order for the device to operate and charge the battery simultaneously. 

The device cannot be charged by a USB cable in the vehicle. 

When connected to a computer or vehicle via USB cable, your device may present a message stating "The attached cable cannot currently charge your device."  This behavior is normal.  While the device does receive enough power from the computer or vehicle to remain powered on and to operate, it does not receive enough power for the battery level to increase".

Andy

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"The device cannot be charged by a USB cable in the vehicle."

Is this in the instructions, or a warning that comes up on the device?     What do you do, if your journey takes longer than the limited battery life of the device?   Stop, and find a wall socket to recharge it?   I know, because I let the cable become disconnected, that my TomTom has a life of about two hours.     I've never heard of a satnav that didn't recharge from the vehicle. it would be a inferior device that didn't, and one I wouldn't buy.

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Just checked, & my satnav is a Nuvi 52 & it will charge, & run from a standard USB lead plugged into any USB outlet.

Bob.

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My nuvi 2515 is the same, runs from any USB connection. My dashcam, a Proofcam PC106, won't - it needs to run from its own cable, which has the cigar lighter type plug. I bought a pass-through cigar lighter adaptor, which also has 2 USB outlets.

Pete

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7 hours ago, RobH said:

There may be no magic involved in USB but there are quirks. A few manufacturers (luckily only a few) make non-standard connections which means that normal USB cables will not work with their equipment. I have encountered a couple of those though not recently. I believe one had put a resistor between the serial connections in the cable. The kit sensed that and would not work without it so you had to have their own cable.  

The other had done a similar trick with the charger unit so you couldn't charge the kit from anything else, even though the USB connection looked standard.  Sneaky.

Hi Rob,

You are correct in that some manufacturers abuse the Universal element of USB and create USB look-alike cables that are non-standard. I do my best to avoid them.

TT

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