Thorn Cycles Forum

Technical => Lighting and Electronics => Battery Charging from a Dynamo => Topic started by: Dave B on March 30, 2018, 10:57:17 AM

Title: Charging from a SON dynamo
Post by: Dave B on March 30, 2018, 10:57:17 AM
Hi, next week I will  be visiting SJS in order to get my Nomad ii serviced . It has a SOM dynamo that power's an Edlux Ii front light. Whilst there I am considering purchasing a charging device to charge an external battery  (Anker 5000) in order to charge my mobile whilst on tour. Any advice / recommendations would be much appreciated. Thanks

[Edited typo in title for easier search -- Dan].
Title: Re: Charging from a SON dynamo
Post by: mickeg on March 30, 2018, 04:41:13 PM
My advice would be to wire it in such a way that you can attach and disconnect devices from your wiring without needing tools.  I use quick connect fittings on my wiring.  I like to be able to move devices from one bike to another.  But if you expect to only use these devices with one bike, that is less of an issue.  I do all my own work, you did not say who is doing the wiring, you or SJS.

I have both devices (light and charger) wired in parallel.  When the light is turned off, all power goes to the charger.  But when the light is turned on, the light consumes almost all of the power.

You will need to decide if you want the USB power port to be in your stem cap (expensive) or elsewhere (less expensive).  That is your call.

If you are certain that you will only use it to charge a battery pack, then a pass through cache battery is not needed.  But if you were charging phones, GPS units, etc., then a pass through cache battery is nice to have so the the pass through battery continues charging your  device while you are stopped at stop lights.

On my Nomad I use a USB charger when touring, but when not touring that charger is not on that bike.  Thus, I just stick it on the bike for the tour.  I attach it to the top tube near the headtube, and remove it at the end of the tour, use a zip tie to attach it.  See photos.

I suspect Dan will have some links with wiring suggestions too.
Title: Re: Charging from a SON dynamo
Post by: Dave B on March 30, 2018, 05:23:27 PM
Thanks for the info. Time permitting I will ask SJS to attach. I don't intend to swap the device to another bike. The integrated headset unit looks good,  but I agree very pricey. Really i just want a basic unit that provides sufficient power to charge a battery in the day which then can be used to charge my phone at night.  Great pics. Cheers
Title: Re: Charging from a SON dynamo
Post by: Danneaux on March 30, 2018, 05:29:17 PM
Hi Dave!

Your results may vary depending on the dynamo output, charging unit, and demands of the device/battery being charged. Results with many combinations are mixed depending on how they are combined.

Most recently, I've been testing the German made Cycle2Charge version 2 by Dirk Langhuber. I have two units, one paired with a SON hub dynamo, the other with an old Sanyo Dynapower [SIC] bottom bracket (actually chainstay) mounted dynamo. Results so far have been encouraging. Build quality is excellent, as is price. Still wringing mine out in full testing to assess efficiency. Jury rigged at present in parallel with my other chargers so I can test directly. Will have further reports when each is fully installed. Preliminary results on my two units confirm the company's claim of USB 2.0 power of 500mA @ 5vdc just past 12kmh/7.5mph and a full 1.0A (1000mA @ 5vdc) above 21kmh/13mph and maximum output remains capped at that for higher speeds. This is higher output than my Tout Terrain The Plug 2+ which is capped at 500mA. It also compares favorably to my B&M e-Werk charger. Keep in mind, this is when powered by SON28 Neu or Klassik dynohubs.

With my Sanyo Dynapower tire-drive dynamo, I make sure the switch on my B&M Cyo R headlight (which in turn feeds my B&M Toplight Line Plus taillight) is turned off when I am charging. Otherwise, I leave the headlight switch on to power the lights when the dyno is engaged on the tire tread. With a tire-drive dynamo it is easy to forget to turn the light back on after charging and lights. Duh. :P The output differs with the Sanyo because that dynamo's output curve differs from my SON28 Neu and Klassik dynohubs. I experimented with several of the half-dozen Dynapowers I have on hand. Those dynamos with factory internal limitation did not do so well as those where I removed it. While I much prefer a hub dynamo, the bike in question is already equipped with the Dynapower and it is convenient and economical for me to leave it in place.

The Cycle2Charge can be mounted on the steerer or -- with the aid of a separate CNC'd aluminum bracket -- on 22.2mm diameter handlebars or quill stems (mine). It has superb internal weather sealing (epoxy-potted electronics) and a rotating top cap that shields the charging port fully when not in use and partially when in use. Depending on the orientation of the charging port, I was happy to find I could charge in the rain with no problem. This can be a problem with most USB chargers as charging in the wet can cause the contacts to burn out due to electrolysis. I've had it happen even with gold contacts, as the soft gold wears off at the actual contact points with the friction of insertion and removal. I made a little rain hood/shower cap for my Tout Terrain connection and charge my devices under cover inside my handlebar bag.

I bought mine direct from Dirk for 59.90 Euro each (and no VAT) and found him to be swift and accurate in shipping, honest and very accommodating of customer needs (my first unit was apparently used as a wheel chock for the postal truck that delivered it, just prior to dropping the package in a puddle and the box bursting in transit. Only one soggy charger arrived in the package; Dirk made good on the missing unit).

One note: When looking at reviews, make sure they are for version 2, as version 1 is no longer available. Dirk tells me there will be no version 3.

English translated company website:
Original German:
Company Facebook page:
Unit at Amazon UK:
Bracket at Amazon UK:
Translated Weraldfietser (World Cyclists) Forum discussion:


Title: Re: Charging from a SON dynamo
Post by: Dave B on March 30, 2018, 06:01:38 PM
Thanks for the very detailed response. I will have a good read and make a choice. Cheers,  Dave B
Title: Re: Charging from a SON dynamo
Post by: Dave B on March 31, 2018, 01:37:24 PM
Hi Dan, via Amazon i have purchased a Cycle2charge v2 ( 52 delivered) I have downloaded the manufacturers instructions. One concern that i have is actual attaching the wiring to the SON dynamo. The manufacturers instructions use a different type of dynamo for illustration with a "plug" to connect the wiring for the light and charger to the dynamo. Is there a simple solution to enable me to do this for the SON dynamo?  Thanks Dave.B
Title: Re: Charging from a SON dynamo
Post by: Danneaux on March 31, 2018, 03:54:32 PM
Hi Dave!

Yes, Amazon has the best price, especially when shipping is considered. I hope it will fit your needs as you wish.

The Cycle2Charge website illustrations show it being wired for a Shimano dynohub. The SON is indeed different, but fear not -- all you need do is crimp a 4.8mm female spade connector to each wire end (there are two ends).

Because the SON dynamo produces AC current, there is no polarity. Once the two 4.8mm female spade connectors are crimped to the wire ends, they can each be slid onto either blade terminal at the doesn't matter which wire goes to which terminal, it will all be sorted out internally.

As mentioned, you will need standard 4.8mm female spade terminals. They are a bit rare in the US, but easily available from electronics stores and bike shops in UK and Continental bike shops or from eBay. Our own SJS Cycles has them in a couple flavors:
Plain, uninsulated @ could use heat shrink tubing to insulate the female spade connectors yourself...or not:

If you only plan to use your SON dynohub for charging, you can stop here. However, if you plan to use the dynohub for charging *and* powering a headlight and/or taillight (either lights or charging, not both at once to ensure maximum power goes to charging), you will *instead* need a pair of 4.8mm crimp-on "piggyback" connectors. These have both female and male spade connections so you can power both charger and lights. One example is shown here at SJS Cycles:
Plain, uninsulated @ 1.50pr:
Insulated @ 0.35ea:

The female spade connectors are a tight fit on the SON dynohub's male spade/blade terminals. This can make it a bit tough to disconnect the front wheel if your hands are cold and/or wet, so some of us prefer to leave these terminals semi-permanently connected and install an additional pair of connectors about 10-13cm/4-5in away, as these connectors are easier to reach when fitting or removing the front wheel. In any case, it helps to arrange the wire pair so it forms a little "drip loop" below the hub terminals. This also makes it easier to attach/detach the wires from the hub. I have some photos showing how I did this on my Nomad, but I am at the moment stopped roadside and the glare on my phone makes it a bit hard to see and find the Forum links to my posts on it. I will put them in a later post when I get home.


Title: Re: Charging from a SON dynamo
Post by: Danneaux on March 31, 2018, 04:04:05 PM
Here we go, Dave; found it:

You can see what others have done in this regard by going to the Forum search function at the top of the page and entering "Deans" (no apostrophe, no quote marks) as the search term (that is the name of the connectors I used. So will bring up other pists, but many other connector types or brands can be used if you wish to install in line connectors).


Title: Re: Charging from a SON dynamo
Post by: Danneaux on March 31, 2018, 04:11:16 PM
Stopped again as further thought occurs...

Dave, if you wish, you can also simply twist together (one each) a charger and light lead and squish each pair to a standard 4.8mm terminal instead of sourcing piggyback terminals.

The downside is if you later wish to change light or charger, you would need to cut off the terminal, but the wires should be long enough to allow it with no problem.

Alternatively, people will sometimes tap into an existing lead wire pair already attached to the hub.


Title: Re: Charging from a SON dynamo
Post by: mickeg on March 31, 2018, 05:06:34 PM
There are lots of ways to do it.

I run one wire pair from the hub to the fork crown, attach the wires to the fork blade with zip ties.  Have a set of quick connectors at the fork crown on the end of those wires.  I used 2.8mm quick connectors.

When I use a charger, I have wired my charger so that the two wires have each a male and female quick connect fitting, that allows me to plug my charger into the wires at the fork crown and plug my headlamp into the other two quick connectors on the charger wiring.  This way both light and charger are wired parallel, to charge I turn off the headlamp.  When I want light I turn on the headlamp and the headlamp sucks up almost all the power. 

In the photos, it is not that clear cut, but the wiring does do what I described above.  But it is a bit more complicated in the photo because my bike computer wire (wrapped around the brake cable) and other things in the photo add some confusion.  In the first photo, the wiring to the charger goes up to the top of the photo, wiring to the light goes to the right edge of the photo.

The wiring looks pretty sloppy in the 2nd photo because the light and charger were installed on the bike for a two week tour, both devices were removed immediately after that two weeks.  Thus, I did not spend much time trying to make it look better.

I am not saying this is the way to do it, I am only saying this is one way to do it.  This way, there are only two wires, not four, going down to the hub.

The photos in my previous post were of my Nomad.  These photos are of my Sherpa.
Title: Re: Charging from a SON dynamo
Post by: Dave B on March 31, 2018, 06:45:01 PM
Many thanks for the advice,  I am heading down to SJS on Thursday so I will invest in the connectors then. Dave.B
Title: Re: Charging from a SON dynamo
Post by: John Saxby on April 30, 2018, 04:14:30 PM
Hi Dave,

I'm late coming to your thread, and won't attempt to add to the excellent advice from Dan and George. 

On the battery, though, here's my experience:

Hope that's helpful, and good luck.

Title: Re: Charging from a SON dynamo
Post by: mickeg on April 30, 2018, 06:45:32 PM
....One last note on storage:  I've been advised by the guys in our local electronics shop to store the batt empty in the off-season, and I do so. (For me, that's usually about 4 months.)....

A Li Ion battery that runs too low often has a circuit built in that will prevent it from charging ever again.  That is some form of safety measure that I don't really understand.  But that is why I never put a Li Ion battery in storage if it is below about 25 percent.  I store them in the fridge, they seem to hold that charge pretty good when stored cold, but I do not store below freezing.  I have had several laptop batteries that stopped functioning after I let them go down to zero and stay there for a while.

I have heard that you do not want to top up Li Ion batteries too full, I have added an app to my Android phone that gives me an audible warning when my phone is charged up to 80 percent so I can quit charging when it gets to that point, the people that wrote the app say that charging up to only 80 percent instead of 100 percent will approximately double the life span of the battery.  (I have also learned that the app will keep making odd noises if my phone is plugged in overnight, which was pretty annoying unless I disabled the warning.)

Maybe googgling Li Ion storage will provide better insight, as I did not offer much.
Title: Re: Charging from a SON dynamo
Post by: Danneaux on April 30, 2018, 07:19:50 PM
As a longtime user of Anker products, I was saddened to see they have decided to remove pass-through charging from their current product line. See entry No. 3 in their FAQ:


Title: Re: Charging from a SON dynamo
Post by: Danneaux on April 30, 2018, 10:58:46 PM
More has changed at Anker...

...Also from Anker's site (FAQ is repeated for all their PowerBank models, one example for their 5,200mAh model here:
Generally, our external batteries' static power consumption is so low it would take between 20 and 36 months to drain completely. However, It is also worth noting that the powercore's chemicals will become less active if left unused for extended periods. To extend your powercore's life, please discharge and recharge it at least once every 4 months.