Have you had your batteries drawn down lately? Or have they mostly been well above 90% for an extended period?
If so you may want to disconnect the charging and draw them down to say 70%, then let things charge again so it can go through all the charging phases and recalibrate.
If you are running wet cell lead acid you can use a hydrometer to check each cell and make sure there isn’t one going bad.
Also, you can give Bogart a call, they are usually very helpful.