If you want the original Kawa parts:

VERSYS® 650 LT ABS DC Power Outlet | Kawasaki Motors Corp., U.S.A.

Charge your portable devices on the go with a 12-volt DC Power Outlet<ul><li>Installs directly into one of two available knock-out ports on the Versys® dash panel</li><li>Dealer installation recommended </li></ul><div>Versys® 650/Versys® 650LT require Relay Kit (99994-0556) or (99994-1677)...

www.kawasaki.com

and also this

VERSYS® 650 LT ABS Relay Kit | Kawasaki Motors Corp., U.S.A.

Purchase as a required component to mount DC Power Outlet, Gear Position Indicator, Grip Heaters, LED Light Bar or other electrical accessories<ul><li>Only one Relay Kit required per Versys® motorcycle.</li><li>Complete plug-and-play heated grip kit replaces stock grips and throttle.</li></ul><br>

www.kawasaki.com

Or have a look online for a USB kit. I know SW Motech makes a nice USB kit that connects to the battery, Or have a look at Aliexpress offerings.

 

warning: don't connect to battery directly.
most will be vampires draining it (seen one sucking 25mA without anything plugged in yet...)

 

If at all you go direct to the battery have a killer switch to save your battery drain. There are many options in the market and very cheap and easy to install.

 

or you do what the bike is already designed to take, which is add a relay and plug at accessory bullet connectors...

 

Original USB outlet are to expensive, you can have USB outlet for 1/5 price of original, and even more cheaper

For example,
I have this USB outlet from aliexpress:

7.09US $ 39% OFF|36W QC 3.0 Touch Switch Waterproof Universal Motorcycle Car Truck Boat Dual USB Charger Socket For Phone Tablet Camera GPS DVR|Cigarette Lighter| - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

You need to buy relay which @Kevinj add in link in second post. Without relay your accessories like heated grips, fog light, USB outlet will not work. You need only 1 relay for all of that.
Also avoid to connect accessories directly to battery, it will drain your battery.

Also here is video to see how to do that job:

 

The easiest and cheapest is probably just to pigtail a connector onto the battery. I have a short 1ft cable that screws onto the battery terminal and an SAE connector on the other end. I can then plug any number of accessories into the SAE connector, such as a battery tender or a USB power plug.

While riding I plug in the USB power plug and then run the cable into my tank bag to power my phone or other devices.

No cutting, no drilling. The pigtails come with a built in fuse. As dddd said, the USB device will suck power all the time, so it has to be on a switched circuit, or if you use a pigtail like I do, make sure to disconnect the USB adapter when the engine is off.

If you want power on the dashboard for sure, you can get longer pigtails, but at that point it would be easier just to use the factory wiring. The relay is super easy to plug into the existing socket behind the instrument cluster. Pull out the plug in the hole in the dashboard, and install the USB outlet. Sometimes there is a problem with whatever is plugged into the outlet interfering with the handlebars.

 

Buy the Kawi relay. Then install any number of inexpensive USB outlets...

Kawasaki Part Number is 99994-0195.

Then find any USB outlet you wish; make sure it fits the location you want and install; it's an easy job.

 

What "AmbientMoto" said...! (Instructions ARE in the OWNERS MANUAL.)

Bought MINE (three over the years) from Cycle Gear for way less than $20 apiece.

 

Thanks guys. You have saved me a headache and some cash to.

 

FYI , the optional wiring in the MK-3 actually has a keyed power source in the front of the bike, if you are that cheap, you can use the coil circuit which is fused at 5 amp. The wiring for the relay only enables the additional wiring for the fog lights or heated grips. Why you would not spend a minimum of $6 for a relay is beyond me. Also if it is strictly for a USB outlet, you could use the city light circuit.

 

 

If you have the aux relay (maybe you have the stock aux lights?) then you can get a 12v socket usb on amazon and connect it to the original wiring (either you make an harness with barrel-style connectors or you simply cut the original connectors and make your own). AUX circuit is limited to 5A total (just FYI).

I would buy the usb from Blue Sea Systems (quality stuff), you can find it on Amazon.

If you don't have the original AUX relay, I would suggest getting it, it's $25 and solves a lot of issues, otherwise you need to buy your own and wire it (not difficult but why bother?)

 

I will install the relay as I intend to add my Denali lights also.

 

Buy the USB port for the 2015 Vulcan S 650. That one works for the Versys 650 but they sell if a lot cheaper. It will come with an extra bracket that you don't need. You will also need the relay. Vulcan® S DC Power Outlet | Kawasaki Motors Corp., U.S.A. VERSYS® 650 LT Relay Kit | Kawasaki Motors Corp., U.S.A.

 

hey i know this one! i bought a less than 20 buck usb port at cycle gear and a relay at the dealer ...easy peasy ..no big deal ..bullet connectors

 

I agree it makes most sense to buy the relay, doesn't need to be the original one. What I will add is that if you are using hand guard like barkbusters (or intend to in the future) The hand guards interfere with whatever you have plugged into the socket. I have damaged numerous chargers and cables and now intend to mount the charger inside the cover (somewhere near the relay) and only have the usb cable coming out to my phone.
I am still trying to figure out a way to keep the usb c-type connector protected when not in use