Charging via USB from my front dynamo hub?

rodgers73

I already have a decent front light to run off my dynamo hub, but would like to charge via usb socket things like my Garmin, my phone etc.

Can you buy a wiring loom that allows that without it running through a light? I don't really want to have to buy a new light given how I already have a decent one.

andymiller

There are at least two firms that make the kit you need: one is B&M (the e-werk) and the other isn't B&M, but I can't remember the name of the gizmo. Have a look around on the sjscycles website. Probably googling something like 'usb dynamo' would also throw up lots of information.

marcusjb

Luxos U is the neatest solution around currently. Not only is it an awesome light, the charging works really well with a USB presentation at your handlebars.

E-Werk is not much less than the Luxos and is nowhere near as neat.

I'd really recommend the Luxos and selling on your old light.

rodgers73

Can I detach the wiring loom from the light if I don't need it?

andrew_s

The B+M USB-Werk is substantially cheaper than the Luxos-U.
There's some wiring involved with both - the Luxos has it's USB socket on a lead in a handlebar switch (non-removable).
Functionally they are pretty much the same - a USB power supply, with a small cache battery that will keep things running during traffic light stops.

The USB-Werk is removable, and you can get screw-in mini-USB and micro-USB cables that bypass the non-waterproof standard USB socket.

If you use a SON hub, it's probably worth getting piggy-back connectors so that you can have both the light and the USB-Werk connected but still easily separable.
With a Shimano or SP hub, you would have to twist the wires together in the connector to use both at the same time, which means having the USB-Werk semi-permanently fitted to the bike.
If you do use both, you'll get a dimmer light and slower charging than either separately, but for low-power use like keeping a Garmin running all night it should be a reasonable choice.
If you don't want to run both light and USB, use separate plugs (as supplied) and plug in whichever you want to use.

The other lights with an integrated USB port are the Axa Luxx 70 Plus and the Axa Nano 50 plus. The beams are reportedly less good then the Luxos, and they don't have a cache battery so you lose power when you stop (whether that matters depends on what you are powering - some turn off & don't automatically turn back on when you start moving).

The neatest option other than in a light is the Tout-Terrain/Supernova "The Plug", which puts the USB port into the stem cap. Not cheap, probably a bit involved to install, and I've no idea how it integrates with dynamo lights, cable connection-wise.


There are an assortment of other options available - Maplin, eBay (various).
However, a common problem with what you might call non-mainstream dynamo USB options is that they don't handle excess power well (connected but nothing plugged in, whatever is plugged in reached full charge etc), and then overheat and die.

rodgers73

Thanks guys - the B&M light looks good as the wiring isnt a big addition to the light generally. Looks like the usb wire just plugs into the handlebar switch, which is a good feature anyway.