The Basement Watchdog Maintenance Free/AGM standby batteries DON’T require any acid or water to be added.

The Basement Watchdog wet-cell standby batteries come dry and must be activated with acid. The life of the battery starts when it is filled with acid. The 2 former models of wet-cell batteries have been discontinued by Basement Watchdog as we chose to focus on our maintenance-free battery model, but some of these wet-cell batteries may still be used in homes or be for sale on shelves at our retail partners.