Ah yes. Solution is as per documentation 
sudo emonSDexpand
pi@emonpi:~ $ df -h
Filesystem Size Used Avail Use% Mounted on
/dev/root 3.9G 1.6G 2.2G 42% /
devtmpfs 484M 0 484M 0% /dev
tmpfs 489M 0 489M 0% /dev/shm
tmpfs 489M 13M 476M 3% /run
tmpfs 5.0M 4.0K 5.0M 1% /run/lock
tmpfs 489M 0 489M 0% /sys/fs/cgroup
tmpfs 50M 128K 50M 1% /var/log
tmpfs 1.0M 0 1.0M 0% /var/tmp
tmpfs 30M 0 30M 0% /tmp
/dev/mmcblk0p1 43M 22M 21M 52% /boot
/dev/mmcblk0p3 11G 113M 9.7G 2% /home/pi/data
tmpfs 98M 0 98M 0% /run/user/1000
warning, you can login by SSH while it is happening but the p3 is apparently missing. As the Pi does not actually shutdown and the LCD does not change, it is difficult to know if it has finished. Not being able to SSH indicated to me it was done.