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Fabrication 101 Everyone has to start somewhere and for some, theOFN might be that somewhere.

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Old 02-04-2016, 01:30 PM
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2Xtreme 2Xtreme is offline
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Help me design a 12v circuit....

Quick electrical question for you:

I purchased a 12V outlet (2.1A) to use for charging my cell phone and powering other accessories.
It's basically a typical cigarette lighter outlet, with a removable insert with a USB outlet in it. So it can be used for either a typical plug-in accessory, or something that requires a USB charger.

I'm not sure if I should set up the circuit (wire gauge and fuse size) for the 2.1A as listed on the outlet, or for the size of potentially used accessory amperage- say a GPS unit, small compressor, etc.

I did some research and thought I had it figured out, but now I am not so sure.
It seems the more I read, the less I know….

Any insight is greatly appreciated?

Thanks in advance,

2X
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Old 02-04-2016, 04:31 PM
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Red face

Your not going to power much at only 2amps!!

Will this meet all your demands ??'

Anything that draws over 2amps does have the potential to heat up your socket and open your circuit protection

No compressor No huge spot lights!!

Figure out just what you need this to do then we can figure out what you need to do it safe and correct

If you need to run higher draw equipment you need a socket designed to handle the load.
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Old 02-04-2016, 04:45 PM
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Agree. If you are going to use a 2amp socket, then you should wire and fuse it for 2amps. That will be plenty to charge your cellphone, but it is not going to work for bigger items. Assuming you stick to the 2amp limit, I would use 16awg wire (GXL or similar) with a 2A fuse.
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Old 02-04-2016, 04:56 PM
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Why not wire it as if it was going to be a Cigarette Lighter say 10 or 12-Ga, and a 15 amp circuit breaker and then plug your charger in and not sweat the 2 amp draw, but you can used it for whatever else should the need be....

E
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Old 02-04-2016, 06:08 PM
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2X it just occured to me that a typical USB outlet is rated to 2.1A. When you say your plug is rated to 2.1A are you refering to the USB plug or the DC cig-lighter type socket itself? I think most DC cig-lighter sockets are rated for 10amps or more. If so, then I would agree with E that you should wire & fuse the socket for as many amps as it's rated for.

As far as the wire gauge goes, 12awg @15amps will have a <4% loss over 10ft of wire. That is generally considered acceptable, so if you are under 10ft I'd say 12awg is more than adequate.

I like GXL wire for this application and I tend to buy mine from these guys: http://stores.ebay.com/ACDCELECTRICPARTS
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Old 02-05-2016, 12:32 AM
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I agree with E and Bandit. If it is a standard 12v cig lighter then wire it with a 10 or 15 amp fuse and wiring. The USB will still only pull 2 amps but then you can run other things as well.

Jaysin
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Old 02-05-2016, 04:06 AM
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Red face

I was just going by the 2 amp socket in this day and age anything is possible.

If it is a normal power port who knows .

In the 2015 Truck there is a dedicated low output socket so labeled.

Who knows.

After watching things get linked to the wrong voltage and wired wrong I tend to be cautious .
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Old 02-05-2016, 11:07 AM
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Well, the main reason for installing the plug is to charge my cell phone, as there is no stereo in the Jeep and typically no signal where I go wheeling. So between the 2 the battery drains FAST.

But I figured if I was going to put an outlet it, why not make it useful for more than JUST charging the phone.

Below is the exact unit I purchased. Hopefully it shows up well enough for you guys, I had to piece it together in MS Paint... lol

[IMG][/IMG]
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Old 02-05-2016, 11:21 AM
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I would run 12V x 15amps to that all day long. The socket is a water-tight marine design. Here's one sold by itself and it advertises a 15amp rating.

http://www.ebay.com/itm/12V-Marine-M...25.m3641.l6368
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Old 02-05-2016, 11:29 AM
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Quote:
Originally Posted by TheBandit View Post
I would run 12V x 15amps to that all day long. The socket is a water-tight marine design. Here's one sold by itself and it advertises a 15amp rating.

http://www.ebay.com/itm/12V-Marine-M...25.m3641.l6368
Well Bandit, I take your word as gospel. So that is what I will do.

The outlet will be located on the dash just on the opposite side of the firewall form the battery. Less than 5 ft run, probably less that 3 feet.

So I will go with 12 ga wire and a 15 amp fuse.
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Old 02-05-2016, 06:51 PM
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Open up the fuse holder and see what rating the fuse in there is.
Wire it in with wire large enough to support that current level.
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Old 02-09-2016, 11:46 AM
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There is a cooler version that has both outlets, dedicated USB and 12V receptacle for CB's etc.

Only GXL wire as Bandit suggested. Once you learn to buy wire in bulk you will quickly realize you have been wasting your money buying a tiny roll from the autoparts store. That tiny roll that cost 4X as much as the GXL is probably PVC jacket or worse and will be a great source of fire if you ever have an issue. Sorry for the rant.
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Old 02-09-2016, 06:52 PM
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The 2.1 amps is what that little rinky dink USB 12volt plug can supply to your phone or whatever USB you plug into it. If you plug two USB things into it it will cut the amps in half and charge each one slower. It will likely not feed each 2.1amps at the same time. Most tiny USB adapters simply do not have the internals to feed that kind of current. You can get larger 12v plug in ones that do but they are larger to deal with the current and heat issues.

Since USB voltage is lower than 12 volts even a tiny wire would feed it (the tiny USB adapter only). But as mentioned above not much else like a spot light or compressor.

That said even a full on starter battery cable feeding it would NOT make that little USB plug in make more than 2.1 amps.

As mentioned above match the wire to the fuse in the holder and you will be fine. When in doubt a little larger can't hurt if the fuse is replaced with the same and proper size.
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