Honda EB11000 Owner's Manual page 56

Refilling Battery Fluid
If the generator is operated with insufficient battery electrolyte,
sulfation and battery plate damage will occur.
If rapid loss of electrolyte is experienced, or if your battery seems to
be weak, causing slow starting or other electrical problems, see your
authorized Honda generator dealer.
1. Remove the front cover and the battery (see page 52 ).
2. Check the electrolyte level in each battery cell.
3. Remove the battery filler caps and carefully add distilled water to
the upper level line. Never overfill the battery.
4. Install the battery filler caps.
5. Install the battery and the front cover (see page 53 ).
54
BATTERY BATTERY FILLER CAPS
UPPER LEVEL
LOWER LEVEL