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?

Thanks.

My recollection is that any of the iphones after the 3G will NOT work without the cache battery. It's really phone-dependent - my E-Werk works just fine charging my Droid Razr without the cache battery, but many phones are quite picky about it.

Gosh, I'm glad you posted this! I've been toying with the idea of getting a dynamo hub wheel to charge my iphone while commuting and touring and the ewerk, I thought, was the perfect accessory. There must be another choice and, if not, some of us need to get together and "kickstart" something. There must be a reasonable market out there.

Never used it, but there are other choices.

These are 2 that I've collected in my list to evaulate when I'm ready to buy one.
https://www.pedalpower.com.au/page12.html
https://www.thinkbiologic.com/product...rge-power-pack

I've had the pedalpower, and the biologic (w/ schmidt hub), and am no longer a believer. You need to maintain a good pace for a long time or risk having the battery actually discharged. If you are going to stay at regular campgrounds, it's much easier and cheaper to get a decent battery for $40, which can charge an iphone 4-5 times. I've never been on a tour where I couldn't fine a place to charge the battery every three to four nights, though I'll grant you that there are seemingly many people on this board who have.

On my latest tour I took two of these, though I never used the second battery. This was for iphone/ipad mini/mifi/dinotte and maybe one or two other things.

I have a battery and it works well.. so maybe the simple solution is really the answer.

Sorry about the delay responding. I ended up buying one of these:

https://www.bike24.com/p238306.html

It has a small on-board battery that's used to regulate the voltage. It's a bit more inflexible in that it will only charge USB gadgets but it should suit my needs. Can always use it to charge one of these:

https://www.amazon.com/Thunderbolt-In...battery+backup

if I want to charge non-USB gadgets. Still hasn't arrived and will then have to get the wheel built. I'll post how it goes.