What size is the SD card and was it fully expanded?
It looks like there is plenty spare in the data partition, you will probably need to reduce the size of /data, then move /data to make room then expand / into the newly freed up area. It can be done from the command line with fdisk, but it is easier via the gdisk gui (not present on the emonSD’s). Needless to say, backup first!
Thanks for the prompt reply.
It was 8GB and fully expanded. I dug a little further and realised it was the backup files that had filled the partition. I have reduced the rolling backups I keep to 2 instead of 7 and reclaimed the space.
I am just about to implement the latest image on a new pi. At the same time I will move backup files to pi/data which is where emoncms puts backup files. With a 32GB SD card I should not have any further issues for a few years!