@enemy85 Is there a follow up message in the log that reads "data is no longer stale"?
There is a difference in your message to most others. Normally I got "Data for UPS [ups] is stale - check driver" but is was followed up shortly after with "UPS [ups] data is no longer stale". BUT the originating process of my message was UPSD.
Your process delivering your data stale messages is originating from UPSMON, which is a little more concerning because it is tied to the shutdown timer of your UPS. For that reason maybe it is a concern. A UPS is useless if it's not going to notify your system that it is on batt. Do some reading here:
http://www.networkupstools.org/docs/man/upsmon.html
And here are the values in UPSMON.conf that affect the running process:
http://www.networkupstools.org/docs/man/upsmon.conf.html
Read up on the POLFREQ value.
Have you added pollinterval= values to your ups.conf aux in the UPS services tab to see if this solves it? How many times is the message repeated in your log, is it once in a while or repeatedly filling the log?
We need more info to help.