Wire 12v USB socket into lighting circuit?

[Wandalust]

Hi,

Looking for some advice please. I have an 2011 Autotrail Apache 634U with an overcab bed.

I'd like to add a USB charging socket above the cargo net in the over cab bed area so I can charge my phone at night and keep it handy.

I've just bought one of these that I hope will do the job - Amazon product ASIN B07H979GBP
The wardobe is next to the overcab and has a light that comes on when you open the door. Am I ok to splice the USB socket into the wires to the light, on the side before it goes to the light switch?

Thanks in advance

 

[deleted-member02]

I've spliced into the 10amp lighting circuit.
All bulbs changed to LED, so plenty of capacity available.
The 2 x USB sockets can draw 6amps max, all lights less than 3amps in total. Hasn't been a problem in four years

 

[pappajohn]

I can't see what amperage the USB socket is but probably 2.1amps.
Bear in mind that's 2.1a at 5v so the actual current draw should only be around 1 amp at 12v.
The volt display will be milliamps.
Lighting circuits are USUALLY on a 10amp fuse (120watts) so providing the total lights is no more than around 100watts it will be fine.

 

[Wandalust]

I can't see what amperage the USB socket is but probably 2.1amps.
Bear in mind that's 2.1a at 5v so the actual current draw should only be around 1 amp at 12v.
The volt display will be milliamps.
Lighting circuits are USUALLY on a 10amp fuse (120watts) so providing the total lights is no more than around 100watts it will be fine.

Many thanks pappajohn. I'll give it a go then

 

[Wandalust]

I've spliced into the 10amp lighting circuit.
All bulbs changed to LED, so plenty of capacity available.
The 2 x USB sockets can draw 6amps max, all lights less than 3amps in total. Hasn't been a problem in four years

Fantastic Hopefully I should be fine then - it's certainly the easiest/neatest way to do it!

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[bigalw35]

I can't see what amperage the USB socket is but probably 2.1amps.
Bear in mind that's 2.1a at 5v so the actual current draw should only be around 1 amp at 12v.
The volt display will be milliamps.
Lighting circuits are USUALLY on a 10amp fuse (120watts) so providing the total lights is no more than around 100watts it will be fine.

Sorry to be a pain in the butt, voltage is voltage, one of the values current is rated in is amps, milliamperes and microamps, sometimes wattage, but deffo volts will always be volts

 

[Stealaway]

Make sure the cable is large enough for the fuse - Do not use standard speaker cable.

 

[pappajohn]

Sorry to be a pain in the butt, voltage is voltage, one of the values current is rated in is amps, milliamperes and microamps, sometimes wattage, but deffo volts will always be volts

Yes they will, but amps vary with volts.
As volts rise in value amps drop therefore 2.1amps at 5v usb output will be around 1amp at 12v battery input.
The only constant are watts.

1a @12v = 12watts
2.4a@5v = 12watts

 

[Hagstrom]

This is interesting as I've been trying the do the same myself. I assumed that having replaced five halogens on the circuit with LEDs there would be sufficient capacity freed up to power my USB socket which will have a load of 650milliamps.

 

[bigalw35]

fairly easy, divide the milliamps by 1000:- 650/1000=0.65 amps (just over 1/2 an amp, in TOTAL), "most" halogen lamps are about 10 watt, so each halogen consumes almost 1 amp and generates a lot of heat to go with it, not only draing the battery but also the life of the lighting fitting

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[bigalw35]

Yes they will, but amps vary with volts.
As volts rise in value amps drop therefore 2.1amps at 5v usb output will be around 1amp at 12v battery input.
The only constant are watts.

1a @12v = 12watts
2.4a@5v = 12watts

absolutely !!! the but that display will ALWAYS be VOLTS

 

[bigalw35]

I've installed the 240 volt version of this meter in our Hymer, works perfectly, mainly for when we're on hook up, so as not to trip to site box (i'm an retired electrician so I know the calculus, but easier to look at a meter) tripping site boxes can be a pain in Europe at night, anyway it's easy to wire in, from Amazon, this one is £13.79, if you go on Amazon and select this meter you'll see the wiring arrangement

MICTUNING Digital Multimeter, DC 6.5-100V 0-100A LCD Amperage Power Energy Meter DC Volt Amp Testing Gauge Monitor LCD Blue Backlight Digital Display with 100A/75mV External Shunt

by MICTUNING

240 volt version, as in our Hymer, also fro Amazon £10.99
KKmoon 20A Digital Voltage Meter Energy Meter LCD 5KW Power Factor Energy Frequency Meters Voltmeter Ammeter Current Amps Watt Meter Tester Detector Indicator