Did I buy the wrong hub? Surely not?
Hi PlanetX!
I think I can clarify. Take a look at the SON product brochure here, in English:
http://www.nabendynamo.de/produkte/pdf/english/Prospekt_SON_28_neu_e_2012.pdfLook at the top graph (the red and black one). Voltage is on the left, speed runs along the bottom.
You'll see the SON28 Klassik/(new) both produce more power at lower speeds than the SON Deluxe. The SON Deluxe (the one with less drag) produces less electricity at lower speeds.
By the time you hit 25kph/15mph, the output is very similar, and by 30kph/18.6mph, the output is nearly identical.What this means is, if you are a faster rider (say a randonneur) who will be riding along at a good clip, the hubs end up with identical output at higher speeds. If you find yourself riding at ~20kph/12mph and below, you'll have more "juice" available at those lower speeds if you use a SON28 Klassic/(new).
If you get a SON Deluxe and ride slow, it will either a) take longer to charge /or/ b) produce insufficent voltage to power some gadgets until you pedal faster. Yes, the cache battery in the Luxos U will make up for some of that difference -- for awhile, until it is exhausted (it does not have a very big capacity). When the Luxos U's internal cache battery is exhausted, the circuitry makes recharging the internal cache battery a priority, so USB output falls. That can cause some USB-powered gadgets to blink on and off under those circumstances until the cache battery is full again. If the gadget is "off" and merely charging, then charging will indeed take longer and may be interrupted until the U's internal cache battery is refilled if it has already run flat.
The SON29 Klassik/(new) can sometimes power the lights and power or recharge devices simultaneously, depending on how much power the gadgets require. In almost all circumstances, a dyno-based charging system will have more electricity available for charging or powering gadgets if the lights are turned off at the time. Running both at once slices the pie more thinly. Similarly, you'll achieve fastest charging if your gadget is turned off while charging. Trying to power it while charging is often too much for the dyno to accomplish -- demand is simply more than it can supply.
Sadly, the one Great Unknown in any dyno-charging system is whether it will work with a particular combination or hub/charger/device. USB-powered gadgets are requiring more current these days, and can be a real challenge for dynohubs designed to deliver standard USB 2.0 levels of power, usually a nominal 5.0vdc @ 0.5A/500mA (give or take a small tolerance window).
Hope this helps.
Best,
Dan.
