iPhone Battery Replacement
Battery Problems for iPhone 3G/3GS/4/4S/5
iPhone 5
As of this posting, iPhone 5 users should go to Apple (QCD) or Singtel/Starhub/M1 if they face battery problems. They will replace you with a iPhone 5. Please understand that refurbished iPhones are not that scary as they are made up to be. They still have to go through the mandatory quality control check every new iPhone has to go through!
iPhone 3G/3GS/4/4S
Beware of fake batteries easily available everywhere on the web. Your iPhone will be reporting wrong battery status, sudden shut downs and when restoring your iPhone you get an error 29 message.
To take care of Li-ion Polymer batteries, ensure that there is charge. DO NOT let your battery go to zero.
Once a month, allow the battery to drain below 20%, charge it up fully to 100% and leave it for 2 hours. This trickle charge will ensure it reaches full charge status.