[PLUG] Phone battery drain

John Jason Jordan johnxj at comcast.net
Thu Nov 22 16:44:10 PST 2012

On Thu, 22 Nov 2012 14:04:20 -0800
Keith Lofstrom <keithl at gate.kl-ic.com> dijo:

>On Wed, Nov 21, 2012 at 05:09:47PM -0800, John Jason Jordan wrote:
>> My Samsung Galaxy S2 battery has suddenly started draining within a
>> couple of hours, even with no phone usage. I have several suggestions
>> from Phandroid forums to try, but one of them seemed a good idea even
>> if it is not the source of the problem, that is, clean the USB jack
>> on the bottom of the phone. 
>While cleaning the USB jack has a small probability of helping,
>there are two more likely causes:  Battery failure, and radio
>failure in the phone.

As it turns out, the problem is due to some errant process in how the
software works with the hardware. Exactly where I cannot tell, although
an Android expert may be able to sleuth it down. The fix is to remove
the battery and leave the battery out for at least a half hour, then
replace the battery and reboot. I had removed and reinstalled the
battery previously without success, but after leaving it out for half
an hour before rebooting the problem is resolved. I am back to my
normal 12 hours or so per charge.

>I just replaced the battery in my semi-dumb Nokia flip phone,
>which used to last a week on a charge (not suprising with 10
>calls a month) and recently dropped to a day.  The replacement
>worked.  The replacement battery was from a spare/identical
>Nokia that I keep around "just in case".  I ordered another
>battery via Amazon for $4.

I bought a spare battery shortly after buying the phone a year ago.
Spare batteries for the SGS2 are about $30. Then again, they are 2150
mah batteries, plus they contain the NFC antenna. Don't ask why Samsung
decided to put the NFC antenna in the battery. Especially considering
that you can't even use NFC with T-Mobile phones yet.

>But standard CMOS silicon is cheaper than GaAs, because 99%
>of all integrated circuits are made with silicon, and most
>of those are CMOS silicon.  Most of the phone is CMOS
>silicon, which is great for the processors and memory and
>such.  So to save a few pennies per phone, manufacturers
>make the power amplifier with CMOS, too.

I wonder if this is related to the fact that you have to leave the
battery out for a period of time before the fix works.

>Whether you use the phone for calls or not, the phone frequently
>sends out "registration requests" to cell towers to let the
>network know where it is. 

I leave the GPS turned on all the time, so the phone is always phoning
home. Yes, I know this means the feds can track me. But it also means
that if I lose the phone I can log in to Where's My Droid from any
networked computer on the planet and get its location within a few
dozen meters. (I have actually done this twice, and both times
recovered the phone.) That's a fair trade-off. Besides, God knows why
the feds would want me, but if they really do want me they can probably
find me without having to track my phone. In fact, they could just call
me and ask me where I am.

>Try not to put it antenna-side down on metal surfaces.

I don't even know where the main antenna on this thing is.

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