Originally Posted on the Yahoo EU2000i Group:

As part of a running change to the popular EU-series models, the green Output
LED functions as an hourmeter. When the unit is first started, the Output LED
can flash based on the total number of hours of operation logged (and stored) by
a circuit in the inverter.

Running time Green Output LED blinking status
Less than 100 hours 0 blinks after start
100 to 200 hours 1 blink after start
200 to 300 hours 2 blinks after start
300 to 400 hours 3 blinks after start
400 to 500 hours 4 blinks after start
Over 500 hours 5 blinks after start

Here are the serial number breaks where the feature was implemented:
EU2000i AC (50-state) EAAJ-2018516
EU2000i AC1 (50-state Companion)EAAJ-2069970
EU2000i AC2 (50-state Camo) TBA
EU2000i AN (49-state) EAAJー2017305
EU2000i AN1 (49-state Companion)EAAJ-2022368
EU2000i AN2 (49-state Camo) EAAJ-2062989

Since the running time is stored within the inverter board, replacing it means
the hourmeter starts back at zero hours.

Related:
The smaller EU1000i got the same change:
• EU1000i 50-state EAGA-1224038
• EU1000i 49-state EAGA-1224009
All EU3000i Handi (pull-start only) models have the feature.
EU3000is Electric start models do not have this feature, but may get it in the
future.