For long bicycle tours using a telephone for navigation is very practical however the power need is an issue. To overcome this issue the power of the hub dynamo can greatly reduce this issue. (USB power banks could also be used but they still need to charged) The forumslader from Jens During http://www.forumslader.de/automatiklader is a great charger for this use-case. You can decide to use the A Head version or the Kompakt version. I went for the Kompakt version because having the capability to charge a phone in your tent or recharge the internal batteries. I also needed to create a housing. The housing is a copy of https://www.thingiverse.com/thing:3148124 from 3dninjaprintor. So 95% of the credits go to 3dninjaprintor. I just made some changes. Like removing the dovetail moint. I only wanted to put the charger in my bicycle bag where it can stay dry and protected.