Digital timer, didn't shut off at all last night. Had to manually power down. Went and bought two new digital timers. Didn't see where it says max wattage 1875w, running 2 1100w Cali ballasts means 2200. Probably why they all eventually malfunctioned.What kind of timer you have?
What time does it shit off at, maybe a pin isnt on properly and causing a time out. Can you manually turn timer all the way around while lights are on to see what time they turn off at?
If you have no plants under light you can also unplug timer and run lights 24 hrs and see if it was just the timer at fault.