iPhone Auto-Lock:

This article appears as a part of my iPhone Battery Saving Tips & Tricks series.

Auto-Lock on iPhone sounds quite self-explanatory; it locks the phone automatically after a defined period of time.

Well it does and it doesn’t.

iPhone’s Auto-Lock applies only in certain circumstances and when using certain apps.

For example, third party apps can and are developed to over-ride the Auto-Lock in order for the screen to remain active.  The same goes for many mapping and navigation apps as well as any other app where the developer has decided to override the Auto-Lock.

This is fine and would be expected in many cases but what does it mean for battery life.  Well leaving the screen active for long periods really hacks away at your battery life so here’s what I believe to be the optimum configuration for a balance between usability, security and battery life on iPhone.

This has been carried out and tested on an iPhone 3GS running iOS4.

Configuring iPhone Auto-Lock & Using Manual Lock/Suspend

Let’s think about this scenario for a moment – if you use your iPhone on average 30 times a day and you don’t manually lock the iPhone after each time and are therefore relying on the Auto-Lock then 30 times per day your iPhone is sitting there on the desk or in your pocket or on your car seat or wherever just shining it’s nice bright screen out into the wilderness.

Now let’s say you lose between 0.5% and 1% of battery life for every time that happens.  That’s 20% to 30% battery life you’re losing just by being a bit lazy!  Get into the habit of manually locking!

So here’s my suggested configuration:

• Manually lock/suspend your iPhone immediately after you’ve finished using it.
• Set your Auto-Lock to the minimum time (1 minute) for times when you forget to manually lock.
• For security and usability, set your Passcode Lock to Require Passcode after about 15 minutes so it doesn’t get really annoying having to enter your passcode every time you unlock the phone

Step-by-step

1. Tap Settings
2. Tap General
3. Tap Auto-Lock
   
4. Tap 1 Minute and then tap General to return to the General Settings menu
   
5. Now tap Passcode Lock and enter your current Passcode when requested
   
6. Now ensure Passcode Lock is set to On then tap Require Passcode
   
7. Tap 15 minutes (or whatever you prefer)
   
8. Press the Home key to return to the springboard.