The iPhone 4S already has pretty good battery life, but if you plan to use it heavily or take it on vacation, you’ll want to know how to squeeze every bit of power out of the iPhone.
Here is a compilation of ways to extend the life of your iPhone without sacrificing your user experience.
If software tweaks aren’t enough, we have a few iPhone 4S accessories to help you get better battery life on the iPhone 4S even if you can’t replace the battery.
Screen brightness

Auto Brightness Adjustment
The screen is one of the most powerful on the iPhone; this means that you should turn your attention to screen brightness first.
Press up and to get there.
Here you can control the standard brightness of your screen.
Turn it on so your iPhone automatically adjusts to brighter and darker settings.
This autotune is key. Without it, a very dim screen will disappoint you when you go out. Auto-brightness isn’t perfect, but it helps keep your screen viewable without using much battery life.
Limit Sync

Close Push
The more email accounts and services you sync, the faster your battery life will go.
If you have more than one email account on your iPhone 4S, go to -> and turn it on when you don’t need extra account sync.
The best example is to close work email accounts while on vacation or on the weekend. This can be a huge battery saver.
Check Mail Less

Receive Mail Less
If you don’t need to be notified as soon as new mail is sent, you can turn off push and set mail to check for new messages less frequently.
Scroll to > and tap .
Scroll down and select 30 minutes or an hour to check for new email.
I choose to check automatically every hour. This helps save battery life and allows me to concentrate on projects without interruption.
You can always check for new messages by opening Mail and refreshing it by pulling down.
Consider Notifications
Push notifications, such as those from instant messaging apps, consume battery life. Turning off notifications will allow you to receive new messages when you open the app, not just visual and audible alerts.
Some apps allow you to turn off notifications at -> location.
While in Notification Center, tap on it for Alert Style.

Check Notifications for Better Battery Life
Others will require you to go to settings to turn off notifications in the app to drain battery using notifications.
This is another area where you have to swap. I limit notifications from apps like Facebook and Tweetbot, but I leave them on most of the time because IM+ and Yammer are very important to me.
Your best bet is to figure out what you can do without and when.
Another tip is to avoid lock screen notifications for apps that send tons of notifications. Every time you get a notification for a new email, your screen lights up, draining valuable battery life.

Limit lock screen notifications
Go ->
Find the app you want to limit and find the .
Scroll to the bottom and switch to .
turn off bluetooth
Bluetooth is an easy way to connect to computers, cars, and headphones, but if you don’t use it often, you can turn it off to save battery life.

Turn off Bluetooth for Better Battery Life
To turn off Bluetooth, go to -> -> and turn the switch to .
Although I don’t use a Bluetooth headset, I usually keep Bluetooth off and turn it on when I’m waiting for a long call or when I get in the car.
turn off wifi

Turn off WiFi when not in use
If you are not using WiFi, turn it off to save battery life.
To do this tap on -> then change to . This is also a good time to close.
Even if you are not connected, the WiFi radio constantly searches for WiFi locations. This is so that you can connect quickly and also help you locate your location.
When surfing on WiFi, you’ll get faster speeds and better battery life than with 3G, so you’ll want to remember to turn WiFi back on.

Location Reminders Impact Battery Life
It’s great that your iPhone 4S reminds you to do things based on your location, but it comes at a cost.
If you set a location-based reminder, your iPhone will track your location until you reach work or home. This can shorten your battery life, so you should use it sparingly.
For example, I won’t be back at my teaching job for another week, so setting a location-based reminder will drain my battery every day. Instead, I’ll ask Siri to remind me at a specific time or set a location-based reminder.
These reminders are perfect for short times, like on the way to work or leaving the house.
If you are in poor coverage areas and your phone is still searching for service or switching between roaming with your carrier, you might be better off turning on Airplane mode.

Airplane Mode Stops Calls But Saves Battery Life
This turns off your WiFi, Bluetooth and 3G connection. This means you won’t receive any new messages, text messages, or phone calls, but if you were looking for services, you probably weren’t getting them anyway.
Go -> Change to:
Remember to turn this back on when you get better coverage. You may want to use Siri to set reminders.

Quickly Auto-Lock to Save Battery Life
Because the screen uses up most of your battery life, leaving your iPhone 4S screen on when you’re not using it is to leave battery life on the table.
If possible, set AutoLock to 1 Minute. If you have set your Passcode lock higher, you can still access your phone without your Passcode, but the screen will turn off and automatically lock after a minute.
Go and choose.
If you combine this with manually locking your phone by pressing the power button when you’re done, you’ll save a lot of battery life. Train yourself to turn off the screen when you put your phone down or put it in your pocket.

Limit Location Services by App
If you need to throttle further, search for apps that use your location without having to. Apps leverage GPS and crowdsourced WiFi to find your location.
This is very important in Maps, but there are Facebook and other apps that use your location without the need for it.
You can turn off all location-based services, but that’s probably unnecessary.
Instead, go to Settings -> Location Services.
Close the apps you don’t want to use your location.
I recommend doing this carefully, as many apps improve your location experience. If an app stops working as you expect, you may need to re-enable location services for it.
If you notice that the battery life has deteriorated a few months after you got your iPhone 4S, you can restore your iPhone to iTunes to get better battery life.
Make sure you have created a valid backup and then use the Restore button in iTunes to restore factory settings.
Finally, restore from your most recent backup and you’ll have better battery life with your apps, data and accounts and hopefully better battery life.
If all else fails, you may need to get a case with a built-in battery. This Mophie Juice Pack Air It is the most popular iPhone case with built-in battery.
For $80 you can get a black, white or red case that contains a 1500mAh battery and is easily removable. With this option, you get a nice battery boost, almost doubling the talk time without a significant volume boost. The video below shows how long the Mophie Juice Pack Air can last and gives you a look at the case.
I also like that this adds a MicroUSB charging port so you can charge the case and your iPhone with a standard MicroUSB cable. This type of case is almost a necessity if you plan to take your iPhone 4S away from outlets to a meeting, conference or vacation.