I am very sorry to open a new thread about battery drain that has been discussed so many times but I am really desperate.
I recently purchased a second hand Nexus S i9020A (unlocked AT&T version) from swappa. (Website that sells only android phones) and I am getting terrible battery life no matter what I try.
The phone is rooted and have tried several ICS roms and all have terrible battery life about 6-7 hours when the phone is on idle for most of the time.
I then installed CM7 as I read that ICS has some battery drain issues, but I still get really bad battery life 6.5-7.5 hours again the phone is on idle for most of the time.
I also tried several kernels.
I tried disabling the WIFI, GPS etc this did not help.
The phone came with two batteries an Anker Battery and the Samsung battery. I sent Anker an email asking them about the battery life, they told me to let the battery discharge to around 10% and recharge to 100% a couple of times. I did this twice, but no improvement in the battery life I was about to do it a third time when I fell asleep the battery must have drained completely and now that battery seems to no longer be working.
I thought maybe I am really unlucky and I got two bad batteries, so I purchased a new RND Battery from Amazon as I thought maybe there were some problems with the Anker. Turned off the phone let it charge for 7.5 hours, but the battery meter still showed that it was not fully charged, but the instructions said to charge for at least 5-6 hours, so I turned on and unfortunately I have the same battery drain.
I have installed a Battery Calibration app from the Android Market to see what the reading was and when the phone read 100% charge it was a little over 4,000 mV . I am not sure if this is what it is supposed to be, maybe one of you can let me know.
In addition I have wiped the battery stats from from the bootloader a few times after I have fully charged the battery and even factory reset the phone but this made no difference.
Last night I even flashed a new radio I went from I9020AUCKF1 to KB3 but this also made no difference. I have been struggling with this problem for about a week with no improvement what so ever.
I read that its bad to completely discharge Li-on batteries, so before I left home to go out, I turned off the phone so that the battery would not discharge, when I arrived home a few hours later the battery was dead even though the phone was turned off. (this was the original Samsung battery not the new battery I purchased, I did not try this with the new battery as yet)
I checked the battery usage and compared it to a Galaxy S2 to see what was using up the battery and the OS and Screen usage % seems to be comparable amount to the GS2.
I also tried a few of the Governors that are included with CM7 and also used the wheatly Governor when I was on ICS, but it made no difference.
Can any one help me? Is there something wrong with the phone? I purchased this as a present for someone who really wanted an iPhone because I could not afford an unlocked iPhone and they are really disappointed by this. I know this may be an isolated case, but I always assured the person that the android phone can do everything the iPhone can do, but not I feel like such a fool.
Can this be fixed? I purchased this when I was in the US but now I am away so returning it would be a problem. Is there a way to check if there is something wrong with the phone itself that's causing the battery to drain at such a fast rate?
Any one that can help me I would really appreciate it and be very thankful, I know there are other topics that deal with battery issues, but I have been researching this for about a week and tried everything I can, I didn't just start a new thread without trying.
The screenshot below shows a high display usage because I was using the phone to try to troubleshoot normally android system uses the most and display is closer to 7% but the uptime is the same. Even though it says 3h 51 mins at 48% in the screenshot the battery seems to discharge faster as it percentage goes down.
