Red, you asked, so here’s how to make it!  :-)

First off you need to get the parts:

First, crack open the USB charger. The plastic outer shell is too big for us!

Basically, take a small screwdriver and pry at the seams where the side connector are. Don’t worry if you break the plastic, you won’t need it!

Next trim off the wires where to attach to the connector on the plastic sides. You want to keep as much of the wire as you can.

Once you’ve clipped those, you’re left with the spring and the wire inside of it. Clip off the spring as close to where it starts curving. You want a little stump of spring for later. Snip off the cap that’s connected to the wire that’s inside the spring as well.

Now you should have the charger with three wires and the stump of the spring.

Strip and twist together the two wires that went to the side connectors. Be careful because these are thin wires and you don’t want to break them. It would be possible to fix but let’s not make more problems to solve. These wires are the negative, or ground, of the charger.

Strip the wire that was inside the spring and twist it around the stump. This is the positive terminal.

I’m not 100% sure that both connections are used, but I didn’t take a chance so I’m leaving everything connected to power as before.

At this point take your soldering iron and solder the twisted wires. It’s easier to tin the wires now and get the solder to flow on them when they’re not attached to the SAE pigtail. Try to use only the heat required to get the solder flowing, you’re really close to some surface mount stuff and like before, you don’t want to create more problems. One lucky thing is that the lead-based solder has a lower melting point than the lead-free solder used on the board — you’re less likely to disturb the existing stuff.

Now we’re to the SAE connector. I just cut mine in half — that way I can make another one of these if I want. Strip the ends and connect like the diagram below shows.

At this point you should be able to test it. The blue LED next to the USB ports should come on when you plug it into your bike.

This is optional, but I like it. Take a bit of clear tubing and cut a strip to go in front of the blue LED.

This acts like a light pipe to get the light to the front. We’ll soon cover it so unless you do something like this the LED’s light will not be seen again.  :’-(

Take some masking tape or something and wrap it around the USB socket and holding the clear plastic in place. Without the tape the epoxy would fill up the USB socket a bit and make it hard to plug things in. The tape will keep the epoxy at bay.

The next problem we’d run into is that the solder joint and the tiny wires are rather fragile. Get some of the epoxy stick and cut off a small chunk. Knead it until the two colors are mixed and form it around the solder joint and wire from the SAE connector. The epoxy I linked to above is not conductive so you can get it all over the board as well. Hell, cover up the whole thing including the USB socket as well!

The plastic tube relays the light to the front.  :-D

The epoxy I linked to above has been verified to be non-conductive (30GΩ is basically an insulator). If you use something else, test it first with a multi-meter. I’m guessing that most of them are, but I didn’t want to lead you astray.

The epoxy sets pretty quickly. In less than 10 minutes you should have, essentially, a rock with a cable coming out one end and USB sockets on the other.