If you are having trouble charging your 12V batteries there are a few things that you can do to ensure that your setup is correct. First ensure that your WaterLily is working properly (click here) and that all of your connections are secure.
Make sure that the adapter you are using has the correct polarity. You can find out more information about polarity and charging 12V batteries here:
Charging is also greatly affected by the flow rates of the water you are using your WaterLily in. To charge a 12V battery you will require a significant flow.