Puck.js Maximum Storage Space?

I can't seem to store more than 40k of data in a file.

If I reset the Puck and do a.....

require("Storage").getFree();

.....I get.....

"=40960"

I'm trying to store movement and temperature data in a file. This works until the file gets to about 40k, then it fails.

Does this limit sound about right (using the latest firmware)? Am I missing something? Can I clear down the storage to get more space somehow?