iPhone 4S battery mystery

Since upgrading from the iPhone 3GS to the iPhone 4S mid-Feb 2012, I have been very pleased with the increased speed, "retina display" and impressive camera. Unfortunately, I have spent a number of hours learning about the "problems" both myself and others have experienced. There seems to be two main complaints (along with many suggested solutions) on various websites and forums:

1. Battery draining too quickly (compared to previous models)
2. Battery not 100% when charged overnight (often 93-100%)

I did experience the battery draining fairly quickly in the first 2 weeks, but after a month, I can confidently say the battery life has improved. I am no longer concerned about running out of juice after a long day of work and going out. It may have been the new battery requiring "conditioning" over the weeks, but the following may also have contributed to the improved battery life: 

• Calibrating the battery by running the phone down to 0% and charging to 100% over night multiple times over the weeks: LINK
• Used battery trickle when charging: Boost Magic and BatteryDoctor 
• Suggestions mentioned on this website: http://osxdaily.com/2011/10/16/ios-5-battery-life-fix-tips/
• Resetting Network Settings
• Disabling unused services (e.g. Time Zone adjustment, Ping, Usage Reports....)

Outstanding "issues": 

• "-" as statistics for "Time since last full charge" (Settings > General > Usage) 
• <100% charge after an overnight charge:
• As other people have suggested, this may be an intentional "feature" of the 4S to prevent overcharging or improve the longevity of the battery.  That is, after a certain period of time at 100%, the device allows the battery to drain to a certain % before recharging is re-activated.  I read that this is similar to what happens with newer MacBooks.
• Look at the data from Battery Logger (via Cydia) below which seems to support this theory:
• 2:45am - 100% - Battery Full
• 5:48am - 95% - Battery has drained and status is "charging"
• 7:10:48am - 97% - Time I woke up - status is "running from battery" 
• 7:10:50am - 97% - I un-plugged and re-plugged the cable to "force" charging hence, the status of "charging" is seen
• 7:32am - 100%
• A suggestion to stop this problem is to switch-off the wifi overnight; however, what may actually be happening is that services, like iCloud, becomes deactivated, resulting in slower battery drain overnight.
• I am yet to find official information confirming that this is an "intentional feature" 
• Note: I also also installed Battery Graph from App Store, but found the data too simplistic 

   

To ensure I get the maximum life for my 4S throughout the day, I immediately unplug and re-plug the charging cable on waking. 30-45mins of extra charging time ensured I left the house with 100% battery life.

What I have not tried yet: 

• A full backup and restore - I can't be bothered trying this just yet. 
• Update 5.0.1 to 5.1 - I haven't done this yet, but there seems to be mixed results with this suggestion
• Un-jailbreak - Not going to try that just yet :)

At the moment, I'm convinced that this is an intentional "feature" as it is not consistent through posts on community forums. Please let me know if you found this useful or have any answers/suggestions!

iPhone 3GS Battery Replacement

I've been very happy with the iPhone 3GS's features and performance, but after 2 years, as expected, the battery life would not sustain the daily activities. I knew it was time to replace the battery when the following happened on a regular basis:

• Thinking about "the next time I could charge my phone" and carrying the iPhone cable around with me
• Fast battery drain and the iPhone suddenly turning off when it reached 20-30%
• Using apps like Boost Magic and BatteryDoctor to "trickle charge" the battery in an attempt to extend the battery life was useless. 

There was only one options to retain the longevity of the iPhone: replace the battery.

Having done enough research and confidence, I decided to save £60-80 buy getting a DIY kit.

Ordered: OEM 3GS Battery Replacement and 3GS Tool Set

Web guides & tutorials that helped me with DIY process:

• LINK 1 - ifixit.com
• LINK 2 - hightechdad.com
• LINK 3 - directfix.com on YouTube

Tips and problems encountered:

• If you feel comfortable at opening up laptops to clean the dust or replace parts, replacing an iPhone battery shouldn't feel too foreign... think of it as a tiny computer.
• Make sure you work in a neat environment; placing the screws in a systematic order to make the process easier. Some have used an empty egg carton to help organise their screws.
• Unfortunately, my 3GS tool kit came with an incorrect screwdriver (I contacted the website who quickly sent me the correct one), but I was determined to replace the battery that day, so used a different screw set to complete the process. Fortunately, the screw set I had was only slightly bigger than the 3GS tool kit; this allowed me to unscrew all but one necessary screw. The only screw I had trouble with was the one to remove the camera, but this did not deter me to complete the process. Although it was challenging to align the connection behind the screwed in camera, I successfully completed the replacement after 3 attempts at pulling the phone apart and putting it back together. I was a pro after 3 attempts!
• My blue plastic tool kit broke when trying to attempt to remove the original battery due to the strong adhesive used to attach the battery to the backing of the phone. The battery was removed by carefully, but firmly using a flat-head screwdriver to pull it out. 

After 2-3 months of using it, I can confidently say the battery replacement was a complete success!

Hope you found this useful!