I have found a work-around for getting Memory Map to see the external sd card.
1. Put all the Memory-Map files you want on to the external sd card. I used the folder /Download/Memory-Map/ since this is likely to be where Memory Map would look automatically in the future when Memory-Map get around to doing an update to the app. But you can pick any folder if you prefer.
2. Root your phone – if you don’t know how, Google it. The only drawback I am aware of is that Sky Go won’t work on a rooted phone.
3. Install Directory Bind – the apk and documentation are here: http://forum.xda-developers.com/showthread.php?t=1410262
. There are four versions of the apk listed and I picked the most recent, version o.
4. Run Directory Bind and grant it superuser access when asked.
5. Add a new entry in Directory Bind:
Source path (for me on Galaxy S3) is /mnt/extSdCard/Download/Memory-Map/
Mount path is /sdcard/Download/Memory-Map/
You need to type the paths exactly correctly, including backslashes, capital letters etc.
6. Once entered, choose More and Backup Database in case you need to enter the paths again.
7. Now choose Bind Checked. If the folders go green, it will have worked: Everything in the folder you have picked on the external sd card, will now appear to Android as though it is on the internal sd card.
I am no expert, so please don’t ask me about this – but it did work for me! I have removed all my Memory Map files from the internal sd-card and put them on the external card, and Memory Map loads happily and sees the maps.
You will likely need to experiment to find which exact source and mount paths are correct for your device - the paths above worked on my Galaxy S3.