PROBE Maintenance Free PREMIUM Batteries under normal operating conditions should never require topping up with water. If cleaning is necessary, wash with soap and water.
It is advisable to check the hold down clamp and the cable connections from time to time to ensure the battery is secure. The state-of-charge can be checked using the built-in visual hydrometer on the battery cover.
Open Cell Vented batteries (with filling caps) will however require periodic maintenance by checking and adding distilled water to the cells as required and by testing the specific gravity of the electrolyte.