12v wiring advice (1 Viewer)

[PJGWiltshire]

I am looking to install a double USB charging socket. The most convenient position is immediately next to the TV station, which in my van is a pop up type from behind a fixed seat. The TV is wired directly into the 12v wiring system and fused as part of the 'Media ' circuit in the main fuse box. The fuse on the Media circuit is 20A.
Having read up on the USB socket ( a double which supplies a 1A and 2.1A outlet) mention has been made that it should be installed with a 10a fuse.

This is where I get confused. My thoughts are simply to splice into the TVs + and - wires and then let the 20A fuse protect the USB charger as it will now be on the media 12v circuit. Will there be issues around the fuse size? My intention is for the USB charger to charge iPhone on the 1A side and the iPad on the 2.1A side.

Hope someone can help

 

[scotjimland]

Fuses are fitted to protect the cable from overload.. so the 20A fuse is fine.

When you splice in, fit an in-line 5amp fuse to protect the new circuit.

 

[PJGWiltshire]

Fuses are fitted to protect the cable from overload.. so the 20A fuse is fine.

When you spice in, fit an in-line 5amp fuse to protect the new circuit.

Many thanks,

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[pappajohn]

Wot Jim said....but 10a sounds a bit high for a USB socket drawing a max of 3.1 amps.
I think i would start with a 5amp, if that blows then a 7.5amp, if that blows theres something wrong.

 

[PJGWiltshire]

Wot Jim said....but 10a sounds a bit high for a USB socket drawing a max of 3.1 amps.
I think i would start with a 5amp, if that blows then a 7.5amp, if that blows theres something wrong.

Will do thanks

 

[Sheddy]

I have had two twin USB outlets both running with an inline 5 amp fuse with no problems for a year or so, I also fitted a switch to each which stops them being powered and the led on when not in use.
Cheers
Ed

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[PJGWiltshire]

I have had two twin USB outlets both running with an inline 5 amp fuse with no problems for a year or so, I also fitted a switch to each which stops them being powered and the led on when not in use.
Cheers
Ed

Good idea thanks

 

[PeteH]

I have had two twin USB outlets both running with an inline 5 amp fuse with no problems for a year or so, I also fitted a switch to each which stops them being powered and the led on when not in use.
Cheers
Ed

Mine has a nice blue LED, which is real handy for navigating to the "loo" at 2am!

 

[Gellyneck]

Mine has a nice blue LED, which is real handy for navigating to the "loo" at 2am!

Why have you got USB sockets fitted in your loo?

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[PeteH]

Why have you got USB sockets fitted in your loo?

Obviously so I can charge the phone whilst texting?.

 

[Pausim]

Wot Jim said....but 10a sounds a bit high for a USB socket drawing a max of 3.1 amps.
I think i would start with a 5amp, if that blows then a 7.5amp, if that blows theres something wrong.

3.1 amps appears to be the output amps, the 12v input could well be different depending on the efficiency of the unit. Also on many devices you need to allow for an initial surge.

 

[Richard n Ann]

It's the wattage that determines the current draw.
1a at 5v will only be 0.41a at 12v.
P=VxI so Both equate to 5 watts

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[Pausim]

It's the wattage that determines the current draw.
1a at 5v will only be 0.41a at 12v.
P=VxI so Both equate to 5 watts

Theoretically correct but that assumes a 100% conversion rate which is unlikely. I was careful to say only that it would be different, because of course I have no idea what circuitry is in use to make the conversion. I would hazard a guess that it will be highly inefficient. Also the initial surge current is unknown. If the advice that comes with the device says 10 amps it may be to allow for this.

 

[Richard n Ann]

Usually a 'buck' switched mode circuit. Highly efficient. The linear voltage regulators are the inefficient ones and need a heatsink, not used nowadays.

https://en.m.wikipedia.org/wiki/Buck_converter

 

[Pausim]

Usually a 'buck' switched mode circuit. Highly efficient. The linear voltage regulators are the inefficient ones and need a heatsink, not used nowadays.

https://en.m.wikipedia.org/wiki/Buck_converter

If that is the case 10A would seem overkill. I had not realised switched mode technology had reached these devices.

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[wizzer59]

Jeeze guys, op stop reading now or else you'll get brain overload

 

[PJGWiltshire]

Indeed, great for everyone input it has been most helpful. I have the USB charger wired up on a 5A fuse, this will be linked to the media wiring circuit which has a 20a fuse. So just need to find a dry spell to wire it all in.

 

[Chrysalis]

I wanted my twin USB charging sockets ( for smart phone and tablet) on each side of the bed so we could both have the devices in easy reach at night ( like we do at home). Our bed is over the "garage" so the panels on the two bedside tables are easily accessible from the garage side. There was already a 12 v socket in the garage fed from the 20A accessory fused outlet in the 12 v fuse box so I diverted this to a new 4-up 12v car type fuse box and wired one of these to the original 12v socket and two others to the two new double USB sockets. The fuses are easily changed in the box, but I have started with 5A ones as I have 11A wiring. The wiring is all concealed in matching trunking in the garage. The scary bit was drilling the 53mm dia holes in the bedside cabinets to install the sockets! I also have the blue LEDs but when not in use these are covered by flaps on the sockets. When in use a small piece of black insulation tape covers them.

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[wizzer59]

Indeed, great for everyone input it has been most helpful. I have the USB charger wired up on a 5A fuse, this will be linked to the media wiring circuit which has a 20a fuse. So just need to find a dry spell to wire it all in.

Why! is it outside? Or do you have a Swift?

 

[PJGWiltshire]

Why! is it outside? Or do you have a Swift?

No got rid of Swift now have a Carthago. The area to wire into is in an outside storage box now the rain has moved on I can get things out and get on with it

 

[Stewart J]

Fitted same twin USB via a switch and a 3 amp fuse which two months on charging an I pad and either a phone or my wife's Samsung tablet at same time often for long periods overnight etc without fuse blowing.

It's the wattage that determines the current draw.
1a at 5v will only be 0.41a at 12v.
P=VxI so Both equate to 5 watts

So Richard is quite correct and I would suggest fitting a 3amp but certainly not more than a 5amp.

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[The Wino]

Anyone know what make the sockets in chausson flash 10's are looking at fitting usb's but want them to match

 

[two]

Remember that if you take your power from the ‘media’ circuit, you will only be able to charge devices whilst the media function is switched on. You may find another terminal in the vicinity that is permanently live (controlled by the main switch rather than the media one).

Whatever fuse you put into your extension will be to protect the additional wire from being overloaded. In theory, you won’t need a fuse if you use the same thickness of wire but it may be considered good practice to do so. The problem with having more than one fuse in a circuit is that you will not know which one has blown if the circuit goes dead and may not know where it is if it’s somewhere inline and not contained within a common distribution box.

 

[Wagoneer]

Expect the OP already knows this, but when the TV is retracted (on a Carthago) a microswitch turns off the 12v power to the TV.
So, will need to spur off prior to the microswitch located at the base of the TV enclosure.

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[PJGWiltshire]

Expect the OP already knows this, but when the TV is retracted (on a Carthago) a microswitch turns off the 12v power to the TV.
So, will need to spur off prior to the microswitch located at the base of the TV enclosure.

I am going all the way back to the main feed where the tv supply is joined to the media circuit. I then will cut into the media supply and fuse from there to the USB charger