Following on from complaints about it’s iPhone 3.1 OS update, Apple has contacted some affected users relating to the battery drain issue and presented them with a list of 11 questions, regarding e-mail, Wi-Fi, Bluetooth and apps.

The note sent to these users includes an attachment that installs a developer level application that logs the user’s iPhone battery life and syncs it to iTunes. Apple asks those who have been provided with the utility to then send those logs back to Apple for diagnostic purposes.