Cross posted in the Touring forum.
Ok, so I'm going to bite the bullet and get myself a dynamo hub. I'll be using it primarily as a power source for my i-gadgets when on tour - primarily my iphone 4 and my ipad 2. I will use a B&M E-Werk to regulate the voltage/ampage from the hub to my iphone. Was just about to buy it all and then read something about the variable voltage not being able to charge the iphone 3GS without the use of a cache battery. The cache battery is another cost in what is becoming an expensive upgrade and I'd rather not get one if I can get away with it.
So, question is can the dynamo hub ---> e-werk ---> iphone 4 (NOT iphone 3GS) charge my iphone and run my gps app while riding without the need of a cache battery?