Tablet shows "Low on memory" warning even though internal memory is greatly empty My tablet shows Low on memory with Total 0.98 GB, 750 MB used even though internal memory is Total 13.65 GB, 13.65GB free
The internal memory is split into partitions, one of them is /system, which I believe is the one with 13.65 GB in size, this one is mounted read-only, meaning you can't install apps on it.

Another partition is /data (the 0.98 GB maybe, i'm not sure though), it is mounted read-write, and it's where apps are installed.

I think there is an option to install apps directly into external storage (your SD card) or at least relocate them from /data partition into SD card.

Yet another option, is to root your device and allocate more space to /data partition.