You will need to have a jailbroken iPhone for this to work. Complete step-by-step guide for jailbreaking iPhone 2G/3G running iPhone firmware 3.1.2.

Once you are done with the jailbreak, follow the simple steps below to enable iPhone 3GS Battery Percentage option in your iPhone 3G and iPhone 2G:

Step 1: Add http://apt.iphone-storage.de repository on your iPhone. To do this:

Start “Cydia” on your iPhone.

Touch on “Manage” tab on the bottom.

Now touch on “Sources” as seen in the screenshot below:

Touch on “Edit” and then on “Add”. You will be prompted to enter a url source as seen in the screenshot below. Type “http://apt.iphone-storage.de ” and touch on“Add Source”.

Cydia will now automatically update your sources by following a series of automated steps.

Step 2: After installation is completed. Search for “asBattery” in Cydia and install this application . This app will automatically add Battery Percentage toggle on your iPhone 2G and iPhone 3G.

Step 3: Now simply restart your iPhone and then navigate to Settings –> General –> Usage. You should now have iPhone 3GS Battery Percentage on your iPhone 2G/3G as shown in the screenshot below:

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