Using Lights & Charger

Modern 6 volt / 3 watt hub dynamos can not only power lights on your bike at night, they can provide power to charge your cell phone or a GPS while you ride during the day. For best results, you should turn your lights off while charging so as to have all of the hub's power available for charging, or disconnect your cell phone or GPS from the charger while using the lights.

The headlight is wired to the hub, as is the charger. The charger converts the A.C. (alternating current) from the hub dynamo to D.C. (direct current). D.C. is required to charge a battery. The chargers come in two styles. One style is a small box that can be kept in a handlebar bag or strapped to a tube of your bicycle's frame with rubber "O" rings. See this page for the E-WERK. See this page for the USB-WERK. The other style fits in the top of the steerer tube on bikes having a 1-1/8" threadless steerer tube. See this page for The Plug.


If you have a Schmidt SON dynamo hub with connectors such as you see in the photo above, you'll need the regular 4.8mm female spade connectors at the end of your headlight wires, and "piggyback" connectors at the ends of the wires to the charger. Technically, that's not correct, since you could have piggybacks on the headlight wire and plain 4.8 connectors on the charger wire. But many people already have a headlight with regular 4.8mm connectors, so on this page I'll always refer to the headlight having 4.8mm connectors and the charger having piggyback connectors.

See this page for general wiring instructions.

See this page for specific instructions for using the Co-Axial wire.

If you have a SON SL hub, only some of what I write on this page applies to you. SON SL hub installations require a special fork, don't use the 4.8mm connectors on the axle, and eliminate the need to connect and disconnect wires from the hub when you install or remove the dynamo hub.

On the left is a piggyback connector. On the right is a standard 4.8mm female connector. They both attach to a 4.8mm male connector the same way. The difference is simply that the piggyback connector has a 4.8mm male connector extending from it.

Here the standard 4.8mm connector is attached to the piggyback connector.

Making The Connections

Here's a Schmidt SON28 hub with its two 4.8mm male spade connectors embedded in the axle.

Here, the wires connecting the hub to the charger are shown with piggyback connectors attached.

And here the wires to the headlight have been attached to the piggyback connectors. This is how the parallel connection is made.

And here's another view of the completed parallel connection. The piggyback connectors are at the bottom, closer to the hub shell. The 4.8mm connectors for the headlight wire are just above.

With some versions of the SON the male space connectors are closer to the end of the axle than with other versions. There's no harm in mounting the piggybacks so that the male connectors are on the hubshell side, giving you more clearance between the wires and the dropouts.

When disconnecting the wires you'll generally want to remove the piggybacks from the hub, taking the other connectors along for the ride so to speak, that way you keep the headlight wires connected to the charger wires and don't have to reassemble those connections. The SON has no polarity, so either wire can attach to either spade connector.

Schmidt has put together a kit of spade connectors and shrink tubing for shops installing and servicing lights.

wiring kit

Schmidt box with assortment of spade connectors and shrink tubing, Part # SCH72800, Price: $ 88.00

Before 2017, your wires would run continuously up to the headlight and charger, and when you took your wheel off you would be disconnecting the wires right at the hub axle. And of course you can still do that, and it's the least expensive way to do the wiring. But in 2017 Schmidt introduced "Co-Axial Connectors" which make it easy to make a break in the wiring when using their Co-Axial wire, and therefor easier to connect and disconnect the wires from your hub when you take your wheel on and off the bike.

An Improved Way To Do It

We have Co-Axial wires all made up with either standard 4.8mm spade connectors or piggyback connectors. The standard length is six inches from the ends of the 4.8mm connectors to the end of the female Co-Axial connectors. Then we offer headlights and chargers with male Co-Axial connectors in the wiring. The connections right at the hub remain the same. But instead of connecting and disconnecting at the hub each time you install or remove your wheel, you connect or disconnect Co-Axial connectors about six inches from the hub. The Co-Axial connectors handle both conductors in the Co-Axial wire. It's very fast and reduces the risk of damage to the connectors at the hub axle.

So what do you do with the wires when you put your wheel on? You'll have two Co-Axial cables with female Co-Axial connectors coming from the hub axle. And you'll have two Co-Axial cables with male connectors from the headlight and charger coming down the fork blade. Both male connectors look the same! Which male connector connects to which female connector? As it's a parallel connection, it makes no difference. Just plug them in and you're good to go.

The Co-Axial connectors add some expense, but also a lot of convenience.

Note! The Co-Axial connectors are designed to fit Schmidt's Co-Axial wire. Other wire might work, but I won't comment on that. What I suggest is that if you are using a headlight or charger without Schmidt Co-Axial wire you should first splice the Co-Axial wire onto your wire before attempting to solder in the Co-Axial connectors.

Co-Axial cable, 4.8mm female connectors to Co-Axial female connector & loose male Co-Axial Connector,
Part # SCH72610, Price: $ 21.00

Co-Axial cable, 4.8mm piggyback connectors to Co-Axial female connector & loose male Co-Axial Connector,
Part # SCH72614, Price: $ 21.00

Download instructions for soldering the Co-Axial connectors.

Jig for Soldering

Schmidt makes a handy jig for holding the Co-Axial Connectors and the Co-Axial wire while soldering the connections. Download this PDF for photos and instructions for its use. The jig has fixtures for both the female and the male Co-Axial Connectors.

Schmidt jig for soldering Co-Axial Connectors, Part # SCH72906, Price: $ 54.75

When charging your GPS or cell phone, turn off the lights for the fastest charge times. At night, don't have your cell phone or GPS plugged into the charger and your lights will be at full brightness.

This is my bike with a SON hub and Co-Axial connectors in the wire to the Edelux II headlight. I don't do multi day rides, so I have no need for a charger. So there's only the one Co-Axial wire from my hub. But this is sort of what it would look like. Just imagine a second wire. ;-)

An Even Better Way To Do It

It's more expensive, but if you're buying both an Edelux II headlight and charger for your SON hub, you can have a cleaner installation by using the "new for 2018" Co-Axial Adapter with "Y Junction".

The Co-Axial Adapter takes the place of two standard 4.8mm female spade connectors, and provides a female Co-Axial connector right at the hub axle. Then you have a Co-Axial wire with a male Co-Axial connector at the hub end, and at the other end of that wire there's a Y Junction where you can connect both your headlight and your taillight. The Y Junction can be positioned anywhere you like on the bike; wherever it's most convenient. The Y Junction requires some soldering, but we can do that for you here. You just tell us how long you want the wires to be and we'll take care of the rest.


Co-Axial Adapter & Male Co-Axial Connector for soldering, Part # SCH72630, Price: $ 33.00

For the "do-it-yourselfer" we have the Y Junction with 80cm of Co-Axial cable attached, and a loose male Co-Axial Connector included. And this is what we would start with if you ask us to make a Y Junction for you with a cable length less than 80cm.

The kit includes shrink tubing.

Y Junction with 80cm Co-Axial cable & loose male Co-Axial Connector, Part # SCH72631, Price: $ 32.00

If you want the Y Junction box to be near your handlebar, an 80cm cable to the hub will typically be long enough. So this kit gives you a male Co-Axial connector already attached, 80cm from the Y Junction. From the far end of the Y Junction you insert a Co-Axial wire and solder the connections inside the box. And you get a Co-Axial Adapter, plus another Co-Axial connector for your other device to plug into the Y Junction.

Instructions are included. And of course you can have us do the soldering here for a small labor charge. You can send us your existing light and/or charger for us to solder connectors to its wire as well. If your light or charger doesn't have co-axial wiring, we will first splice Schmidt Co-Axial wire to your wire and then install these connectors.

Download the instruction PDF.

The kit includes shrink tubing.

Y Junction with 80cm Co-Axial cable, attached male Co-Axial Connector and Co-Axial Adapter,
Part # SCH72635, Price: $ 67.00

Here's the Y Junction installed in the Edelux II wire.

Schmidt has put together a kit of co-axial connectors, shrink tubing and soldering jigs for shops installing and servicing lights.

tool kit

Schmidt box with assortment of Co-Axial connections plus the jig for soldering, Part # SCH72650, Price: $ 283.00


To see how to mount headlights and taillights, go to the mounting lights page.

Back to Schmidt hub page

Back to Lighting Systems page


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This page updated: Tuesday, March 10, 2020

Peter White Cycles LLC
24 Hall Rd.
Hillsborough, NH 03244
603 478 0900 Phone