Hi Huub, and welcome to the Thorn Cycling Forum!
In answer to your question, I am in the process of detailing my own setup, which has now proven to work reliably on my Nomad.
I'm busy today exploring and mapping a new touring route by car through some very rough country and will give more details later in the week. In the meantime, here is a thumbnail sketch of what I am using successfully on the Nomad:
SON28 (new) > Tout Terrain PAT cord (lowers the speed at which max charging takes place) > Tout Terrain the Plug2+ > 2200mAh buffer battery > my Garmin Oregon GPS or cellphone.
This works very well, and The Plug2+ starts supplying full power (5VDC @ .5A/500mA) at speeds as low as 12kph/7.5mph.
I usually use this setup without the buffer battery, since I usually use it to charge AA or AAA Eneloop cells in an Eneloop USB charger or to directly recharge my other gadgets with embedded batteries (my Panasonic electric shaver, for example, or my "dumb" cellphone, or flash vidcam).
However, when I wish to power the GPS continuously (~20 hours) for track-recording and map-making, then I use the buffer battery, or I use the buffer battery to power the cellphone continuously in places where I want the phone on but battery consumption would be unusually high because of my distance from cell towers. In both these cases, the device(s) operate continuously and I wish to either maintain charge (as much as possible) while they are operating or minimize loss of power (amounts to the same thing). It is extremely difficult if not impossible in my present experience to create a charging system that will operate a high-draw/high-drain device *and* result in a net charge of the device at once. The most I have been able to accomplish in such circumstances is to extend operating life by coupling a buffer battery with charging. I made my own patch cords and connectors to accomplish my goals.
To replenish my batteries during extended travel away from mains power, I supplement my SON28 (new) dynohub with a Joos Orange solar charger and accumulator battery (the 5400mAh battery is inside the case for the solar panel). I use the dynohub during the day (with or without the 2200mAh buffer battery) to power my gadgets in real time and to charge AA/AAA cells in the Eneloop charger. Of course no charging takes place at night when I am at rest and sleeping.
The Joos Orange solar panel *only* charges its own 5400 accumulator battery during the day, and is then used to recharge other devices when I arrive at camp or overnight while I am sleeping. If I used it during the day to charge other gadgets or batteries, I couldn't keep up with demand, since it requires a maximum of 12 hours' sunlight to charge its own battery from flat.
I did convert my Extrawheel traier with its own SON28 Klassik hub and a B&M e-Werks charger set to nominal USB 2.0 voltage and used it as a supplementary charger for keeping another set of AA/AAA cells going or for charging my other (powered off) gadgets while riding. It worked very well, but full-power charging did not take place until slightly higher speeds of around 15kph/9.5mph, and so was not as well-suited for charging when crawling up steep hills. When I do not take the trailer with charging system, then I may supplement my existing setup with another Joos Orange solar panel/accumulator for my extended journeys away from mains power.
In my own use, I have found a few rules of thumb for charging high-draw/high-drain gadgets:
• Most bicycle-powered devices output USB 2.0-standard 5.0vdc@500mAh. This is sufficient for older devices, but woefully inadequate for newer devices that are really designed to be charged in 1.0A/1000mA or even 1.5A/1500mA. The result is ether very slow charging -- or none at all, if the batteries for those devices incorporate a minimum-current threshold for charging to initiate. This can vary depending on whether the battery to be charged is fully depleted or partially charged; in other words, it depends on the device.
• Charging is most effective if the device can charge while in the powered-off state. Charging will be slow or not occur at any appreciable rate while the device is operating.
• A device may still be powered by the dyno-charger, but it may (more slowly) deplete its internal batteries while doing so.
• A buffer battery can power a high-draw/high-drain device longer than the device's internal batteries alone, however, it is also true that a bicycle dynohub cannot recharge a buffer battery (much or at all) while it is charging/operating a high-draw/high-drain device. This is not a problem if you can occasionally top-off the buffer battery from mains power, but for extended time away from mains power, it is a losing battle.
• Solar can be an effective supplementation for dynopower, but is not enough by itself to substitute for dynopowered charging.
• A small *~2200mAh buffer battery can be charged by dynopower and/or solar power and still serve as a shorter-term buffer to extend the operating life of a high-drain, high-draw gadget.
• The classic conundrum of charging/capacity is this: High-capacity batteries are wonderful for powering gadgets, but they take longer to recharge themselves.
• If you can periodically recharge your gadgets and buffer battery from mains power you'll do much better than if you spend extended time away from mains power. My own goal is to be entirely independent of mains power, and it appears I've achieved it for my needs and gadgets. -- except the netbook, whose charging requirements exceed what the bike can supply.
• The Tout Terrain The Plug 2+ needs the "Plus" part (the PAT cord) to be most effective at charging such devices at realistic touring speeds. I have also found The Plug will still charge (albeit it at a much slower rate) while its green light is blinking. At a certain point, the green light will come on solid once the battery has reached at least a minimal charge.
A few of the early PAT cords proved to be defective and would result in either no charge or reduced charge with a blinking green green light. The problem has since been corrected and there is now a Tour Terrain The PlugIII with the corrected PAT cord.
I will make a full report in a separate topic later, but hopefully something in the above will prove helpful in the meantime.
Best,
Dan.
