How do I know when to charge the battery or how often should it be charged?

You can check the battery status in one of two ways;

1. Tap Edit->General Settings->System Tab->Power Button and look at the battery power remaining.
2. Program a button with the action Battery Status so that when it is pressed it will report the percentage of battery power remaining.

           a. Go into Edit Mode(Tap Edit->Edit Mode).

           b. Press and hold on the button you want to edit and tap on Edit Button(or Create New Button) to  

               open the button editor.

           c. Enter a label and select an icon. Tap on the Action tab. Tap on the drop down arrow and select 

               Battery Status.

           d. Tap on Add so that it adds the action to the actions list box.

           e. Tap on OK.

When the battery power drops low enough a low battery message will be displayed on the screen. If the device is used during the day, then it should be plugged in at night to charge it up.