Dynamo charger help

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  • Dynamo charger help
  • Premier Icon Mr Agreeable
    Subscriber

    I’ve got a Kemo M172 controller which I’m planning to use with a Schmidt SON hub to charge GPS, phone, etc. However the wiring instructions on the Kemo website are causing me some confusion:

    http://www.kemo-electronic.de/en/m172_setup.php

    Am I correct in thinking that the SON hub is AC, and therefore it doesn’t matter which way round the “light” and “dynamo” wires are connected? If not, how do I find out which connects to “the centre of the lamp”? Using a Solidlight head unit which is really well-sealed so I’d rather not pull it apart.

    Can Bez or anyone shed some light?

    Premier Icon Mr Agreeable
    Subscriber

    Google search isn’t turning anything up from there.

    Embarking on my first proper foreign tour in ages soon, so any advice would be appreciated…

    TheBrick
    Member

    Your dyno hub is AC however maybe the device is expecting a DC connection?

    Premier Icon Mr Agreeable
    Subscriber

    The specs on the back of the packaging clearly state “Input voltage: 6V AC commercial bicycle hub dynamo (also wheel hub dynamos). Output voltage: 5.2 V DC stabilized.”

    There’s a review here by someone who is using one with an SON hub and says he wired it up by “trial and error”; personally I’d rather know what I was doing before I start soldering.
    http://www.crazyguyonabike.com/reviews/board/message/?thread_id=213301&page=1

    Nicknoxx
    Member

    That’s the worst ‘wiring diagram’ I’ve ever seen. However looking at the product in this picture:-
    http://www.kemo-electronic.de/images/ArtM172_1000x750.png
    It’s seems quite straight forward.
    The right-hand wire (I assume 2 core, it’s AC so polarity doesn’t matter)goes to the dynamo. If it’s single core, one of the dynamo terminals will have to be grounded to the frame.
    The middle orange wire goes to the lights
    The left-hand orange wire goes to the frame so the bike acts as one of the wires.
    Where did you buy it?

    The instructional video makes it perfectly clear 😯

    [video]http://www.youtube.com/watch?v=HNlCwaYjNDM[/video]

    Premier Icon Mr Agreeable
    Subscriber

    eBay purchase, hence why I’m asking numpty questions on here.

    The wiring for an SON hub isn’t grounded to the frame, (it says here) hence my confusion over what to do with the “ground” wire.

    Premier Icon Mr Agreeable
    Subscriber

    The instructional video makes it perfectly clear

    Yeah, doesn’t it just. 🙄

    If that bike in the video was a musical instrument, it’d be this:

    Premier Icon Mr Agreeable
    Subscriber

    Found this, rendered near-illegible by Google Translate:

    A son dynamo has no mass point, but if the headlight with a metal bracket on the frame is the system from the lamp base grounded. The earth wire is the outer jacket of the coaxial (in the case of the black insulated plugs. The tension thread is brown, transparent

    http://translate.google.co.uk/translate?hl=en&sl=nl&u=http://wereldfietser.nl/phpbb/viewtopic.php%3Ff%3D21%26t%3D13903&prev=/search%3Fq%3Dkemo%2Bm172%2Bson%26start%3D10%26hl%3Den%26client%3Dfirefox-a%26hs%3DyH7%26sa%3DN%26rls%3Dorg.mozilla:en-US:official%26biw%3D1024%26bih%3D644%26prmd%3Dimvns&sa=X&ei=TQDnT8vpN-mQ0AXmzvCUCQ&ved=0CGQQ7gEwCDgK

    Rik
    Member

    Not sure if you have or haven’t considered the Tout Terrain Plug 2, or if you dismissed it because of price.

    But i bought one a few months back and used it on a recent bike tour. Very impressed and it worked faultlessly. Very neat small design too. I’ve just bought the power enhancer tube thingy from SJS Cycles. So it should work even better and lower speeds.

    They are expensive but they are good.

    Premier Icon Mr Agreeable
    Subscriber

    I’ve seen the Plug and if money was no object I’d buy one like a shot, but £25 versus £125, for something I’ll only use occasionally, steered me towards the more DIY route.

    Rik
    Member

    Yeah I totally understand it is a redicilous amount but now I have one it does work well, is small descrete and well made.

    Def better than the e-werks version

    The hub outputs AC and the light is expecting to see AC, so you do not need to worry about which wire is which to and from the hub or the light. The only DC stuff is sealed within the light circuit and within the sealed charger circuit to make it (hopefully, but not necessarily, clearly!) “easy” for you to wire up.

    I have a Kemo unit, which I use alongside my earl dynamo light, which my mates nicknamed “the deanamo” so I am speaking from my personal experience. The Kemo charger works very well, and hasn’t exploded my Garmin or my phone!

    Premier Icon Mr Agreeable
    Subscriber

    I eventually wired this up using the frame and dynamo contacts only, and didn’t bother trying to connect the light inline (In any case, I read some forum posts saying that it causes the power of the light to drop off).

    It works very well for unfussy USB devices like my Satmap GPS, though my Android phone seems a bit more temperamental and speed-dependent.

    It does mean you have to swap the light and charge connections over, rather than just flicking a switch, but you can also get piggy-back spade connectors from SJS Cycles that would probably do the trick if you can’t be bothered to faff around connecting and disconnecting (I’m not sure whether this would let you run a light and charge a device at the same time. Probably not.)

    Premier Icon Bez
    Subscriber

    Oh, I missed this first time round 🙂

    As you’ve found, it works fine connecting the dyno lead to the live wire and the frame lead to the earth connection (though as Rob points out it probably makes no difference — in fact I’m not sure the spades I connect it to are even designated). I use mine connected in parallel with my IQ Cyo, which has spades trailing out of the back for a rear light. It makes absolutely no difference to the light output IME — though you have a different light so YMMV. So if you want light and charge at the same time then you should be able to rig it up in parallel.

    It’s worked fine for me when I’ve used it, whether charging a Garmin or a phone, provided I’m doing more than walking pace. Can’t recall if I’ve used it to charge a USB battery but it ought to be ok. Electronically it seems sound as a pound, just a bit of a pain that the wires are awkward lengths and the body won’t mount sensibly to anything (I really have no idea how they think you’re supposed to attach it to anything). Would quite like to know what’s inside the Kemo so I can try building the same electronics into a more convenient shape…

    Premier Icon Mr Agreeable
    Subscriber

    I’ve not found mounting it too much of a problem. A short rubber band round the tabs on the side secures it to the fork leg of my Crosscheck. I thought it would come loose instantly on off-road sections but it’s been fine. It just looks like a bit of a carbuncle.

    It’s a bit too well-sealed and expensive to be worth pulling apart, but someone on CGOAB claims to have made something home-brewed that’s just as good:

    http://www.crazyguyonabike.com/reviews/board/message/?message_id=234206

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