steiny and hugo4 :
To have maps on extcard with oruxmaps, it's easy (tested with 4.1.2 and 4.4.2 without root).
1. After complete installation, you have to create a folder in extcard like that :
/storage/extsdcard/oruxmaps/mapfiles
2. in mapfiles, copy maps as you want.
3. Open the application.
4. In the right top corner, open the 3 points to have Global settings.
5. Open Maps.
6. Open Folder for maps and choose /storage/extsdcard/oruxmaps/mapfiles.
7. Close the application and reopen it.
Then you have to try the maps.
1. Open Maps (top right below the 3 points).
2. New map.
3. Offline
4. Only have to select a map.
That's all !