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Discussion Starter · #1 ·
Hi,

I'm looking to hook up a USB socket to my motorcycle under the seat with a permanent USB dongle plugged in (for a car park gate). The idea is to tap into the Licence light ignition switched wire with something like a Posi-tap connector and into a Normally Open relay.

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Hopefully, the device will only be powered when the bike is on so I won't have to worry about it draining the battery.

If anything is obviously wrong feel free to yell out as it's my first time doing something like this.

Thanks
 

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Diagram looks OK. Pick up the supply from the brown wire in the rear light. Feed through a relay and the USB can get its supply from the battery (through a fuse). It will only be live when the ignition is on. I run all my accessories - heated grips, DRLs, GPS and USB - through a fusebox with a setup like this.
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Discussion Starter · #3 · (Edited)
So I was doing some reading and was thinking if i could just leech power from the fuse box with a fuse socket wire tap and avoid having to deal with a relay and splicing a live wire.

Haven't checked but i'm assuming at least one of the fuse box sockets will be ignition switched and not constant.

Thoughts?
 

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Discussion Starter · #4 ·
End result:
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Fuse socket wire tap (the 10A for the fan which is ignition switched) crimped to the SAE terminal (grounded directly to the battery), connected to USB charger device. Had to butcher the fuse box and zip tie it closed and the wiring isn't great but it works :)

The SAE lead has an in-line fuse, wondering if something happens do both fuses get popped or just one?
 

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Path of least resistance. As long as the in-line fuse is smaller than the one the circuit is attached to in the fuse box... just the in-line.
If both fuses were the same size, why bother using the in-line to begin with? The whole idea of an in-line fuse is to give protection to a device, while isolating the device from the complete circuit it's pulling power from.
 

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Discussion Starter · #6 ·
Path of least resistance. As long as the in-line fuse is smaller than the one the circuit is attached to in the fuse box... just the in-line.
If both fuses were the same size, why bother using the in-line to begin with? The whole idea of an in-line fuse is to give protection to a device, while isolating the device from the complete circuit it's pulling power from.
The lead and inline fuse came with the usb device haha.

Both are 10 amp fuses. Should i get a 5 amp fuse for the in-line instead?
 

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🔴 I'm not as qualified to answer that as well as others on this Forum...I'll defer to someone more electrically inclined to answer with any authority. 🔴
I have no doubt the USB unit you purchased is capable of handling 10-amps, and that's good... it should be a well-made unit.
With my limited knowledge, I would drop to a 7.5- or 5-amp for the in-line fuse serving your USB outlet.
I've installed and have used heated grips that draw less than 4-amps, so I can't see a need for a 10-amp unless you plan to double up with several heavy-user components at once.
You'll be able to decide your needs better than anyone else... Charging a phone? or wearing a full array of heated gear that 'may' push the limits of a smaller fuse?
 

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Discussion Starter · #8 ·
The device is listed as: Output: 5V/3.1A Max. (shared, Dual USB)

Might ask the electronics store guy if it would be a good idea to change out the two 10A fuses for 5A ones.

I only plan on putting a USB dongle on it for a car park gate but not sure what the actual draw of the device will be.
 

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If all you want is to add a USB dongle under the seat, you may be over-engineering things. Like a lot of people, I use a BatteryTender smart charger over the winter for battery maintance. It comes with a 7.5A fused SAE quick disconnect cable that can also be purchased separately. SAE (society for automotive engineers) is a standard connector and you can get a USB outlet that plugs into it. BatteryTender makes one and there are numerous aftermarket ones on Amazon or eBay. This route is easy (just screw the cable on to your battery and run the end to a convenient location. It's got an inline mini-blade fuse and you can unplug the USB adapter whenever you want to use the cable for other things like maintenance charging your battery over the winter or plugging in an emergency micro tire inflator for fixing a flat. Here's what it looks like on my bike. Good luck.

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Because of the stupid placing of the battery on the CB300R I added extension cables to a heavy duty fuse holder. This provided a convenient point to connect to whet otherwise would have been the battery. All my 12V supplies can be picked up from this ( alarm, battery tender pigtail and supply to my fusebox with all accessories). All earth (ground to US types) wired go from a common earth point to the negative on the HD fuseholder.
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