Troubleshooting a battery-sucking iPhone 4s [via Daring Fireball]

I wish that I had known about “Settings → General → About → Diagnostic & Usage → Diagnostic & Usage Data” before. My iPhone 3GS battery would drain quickly on road trips to my best customer. My “solution” was to delete and then add my Exchange email, calendar and contacts. I might have found something useful if I had known where to look.