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Discussion Starter #1
I'm installing two Motopower waterproof USB power ports on my bike. Both ports are rated at 3.1 amps, and are going to be used to power a GPS and a cell phone attached to my front accessory rail (I have a Super Tenere). I don't believe that the draw on either my GPS or phone exceed 2 amps. The Motopower ports appear to be wired with 18 GA wiring, though it isn't marked so I'm not sure. I have quick disconnects attached to each port so they can be easily disconnected for replacement or removal. I have a PC-8 mounted under my seat on a switched relay.

I'd like to wire the ports in series, with the two lines coming together immediately after the quick disconnects, in order to simplify the wire runs and so I only have to use one connection in the PC-8 (it's getting kind of crowded under the seat). The maximum amperage per circuit on the PC-8 is 20 amps (15 continuous). I was planning on using 14 gauge stranded wire for the supply line from the PC-8 to the two USB ports. The run from where the two ports would merge and the PC-8 is about 2 feet, maximum.

I'm not an electrical wiz, so:

Is there any reason not to wire it this way?

If they are wired in parallel, what size fuse should be used, based on the information above?

Thanks all!
 

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FORUM GODFATHER.....R.I.P. PAT
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I'm not sure if you are clear as to what series and parallel mean. You need to wire them in parallel. Series is on the left and parallel on the right in the diagram. The battery would represent the positive and negative connections in your PC8. The light bulbs would be your USB ports.

 

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You will be fine. Stranded wire can handle more amps than solid so you have to look at a stranded wire chart:
https://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

For usb charging ports you could even get away with 16ga

Just make sure your wire is properly shielded in a protective case or apply loom where chaffing might occur.

Btw, I love West Marine's tinned copper stranded duplex wire in a heavy sheath...stuff is perfect for wiring on bikes:
https://www.westmarine.com/buy/ancor--duplex-wire-by-the-foot--P009_274_003_002
 

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FORUM GODFATHER.....R.I.P. PAT
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18ga will be plenty and can handle a 10A fuse.
 

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Discussion Starter #5
I'm not sure if you are clear as to what series and parallel mean. You need to wire them in parallel. Series is on the left and parallel on the right in the diagram. The battery would represent the positive and negative connections in your PC8. The light bulbs would be your USB ports.

LOL, actually I do know, but somewhere between my brain and my typing fingers that got switched around. I understand the difference between the two.
 

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Discussion Starter #6
You will be fine. Stranded wire can handle more amps than solid so you have to look at a stranded wire chart:
https://www.westmarine.com/WestAdvisor/Marine-Wire-Size-And-Ampacity

For usb charging ports you could even get away with 16ga

Just make sure your wire is properly shielded in a protective case or apply loom where chaffing might occur.

Btw, I love West Marine's tinned copper stranded duplex wire in a heavy sheath...stuff is perfect for wiring on bikes:
https://www.westmarine.com/buy/ancor--duplex-wire-by-the-foot--P009_274_003_002
Thanks Motor7. I have some 16 GA from a previous project that I'll probably use; otherwise I'd have to go buy 18 GA. I sheath all my wires with PVC tube sleeving, that I get from McMaster Carr. I bookmarked the West Marine site for future reference, so thank you for that info.
 

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You can pick it up on fleabay cheaper, but it would take me a few years and a new bike to too to use 100'.......oh wait
 
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