There are two things you can do to help.
1. Use the autolock feature which will automatically switch off after 5 seconds if a code is not entered, especially helpful for accidental switch ons.
2. ActiveSync can start on its own and run in the background, to prevent this do the following.
Start your P350/P550. Go to Start – Programs – Activesync. Tap on Menu then Add Server Source’ Enter 1, 1, 1, 1 as the server. User a Password b Domain c Next uncheck the boxes End. Now go back to Menu – Schedule and use the two sliders to select each as Manual OK Now go to Activesync - Options, where you can delete the Server you’ve just added. It will now keep the Manual settings. You will still be able to use Activesync in the normal way but you’ll find it no longer auto-starts when it’s left alone, thereby saving some battery power. Mio recommend a ‘top-up’ at least once per week. There is also a Mio Power patch from http://www.mio-tech.be/en/support/P550-downloads.php