Is the data stored through localstorage saved in a telephone conversation, even after disconnecting / restarting the application / phone? If not, should sqlite be used instead?
Yes, but you are actually using the HTML5 web storage (great entry here ) to store persistent data, not phone unlock.
I wrote a tutorial for using local storage (on PhoneGap / Android). If you are not interested in the full tutorial, find examples of their use on the page "localStorage" and "JSON" (for parse () and stringify ()).
phonegap 1.4.1 on android 2.3 (level 8 api level) does not save data either through localStorage or through websql through turning off / on the power of the phone. makes it useless. try the api file instead.