[Galaxy S I9000 General] Prankey:
Seems most of us have not noticed:

GB stops the charger supply on our SGS as soon as the battery is fully charged and then your phone uses BATTERY instead of charger to keep itself on!

If your phone has some apps running which drains the battery fast, your phone will drain the entire battery and will shut down when the battery is dead!

This is very dangerous for the battery to discharge every day because of this bug and Samsung and most of still haven't seems to notice this!

I have tested this several times now and downgrading the Froyo fixes the issue.

This issue occurs even when the phone is sitting idle with minimal battery drain for several hours connected with charger (in such situation the drain is minimal with few percentage like when you disconnect the charger.

Let me know if some of you have different experience as my phone definitely has this issue which doesn't exist if I downgrade to Froyo.

We all can check this behavior:

Charge the phone till it says 100% charged. Use the phone normally or heavily for several minutes (like web browsing). Keep it connected to charger while it says "Charged" 100% for a couple of hours (to ensure that you did not drain the battery beyond charger capacity). You would still get much lesser than 100% charge after removing the charger (try using battery indicator tools which tells exact %age of battery).

This bug exist on all the Gingerbread images I have tried including official and those based on JVP 2.3.4

Read below how lithium ion batteries work best if used around full charge (without over charging - Phone and Battery has protection circuit) during regular use:

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Thanks to "$omator"

Use this software to test your battery: https://market.android.com/details?id=ccc71.bmw

Deeper than 10% charging and discharging cycles unnecessarily will significantly reduce the lifetime of the battery. Hence when phone is plugged, it should charge battery to 100% and power the phone through charger after stopping charging. Samsung usually stop charging around 96% of full capacity of battery to avoid over charging. After disconnecting the batteries once around 96% was achieved, it will restart the charging cycle around 95%. Hence all builds till Froyo reported close to 100% charge level and never less than 95% when disconnected from the charger.

GIST - Batteries should maintain floating charge voltage to avoid depletion and wear unnecessarily while connected to the charger after full charge and phone should run on Charger ONLY. Instead, Samsung goofed up Gingerbread drivers to switch off the charger and run the phone on batteries randomly draining the battery sometimes completely. GB OS thinks phone is running on charger and hence show 100% charge and RAPIDLY drains the battery till it goes dead when batteries go dead (randomly)!

Last screenshot is from Froyo. Attaching more on a later post on how stable it is in Froyo.

EDIT 1st July - More screenshots on how Froyo maintains stable voltage and do not consume battery power (current) in post #57: http://xdaforums.com/showpost.php?p=15228263&postcount=57

Screenshot #5 and #6 tells the DROP in battery voltage as soon as the charger is connected (200mV!) which speaks how much the GB OS consumes more when plugged in and STILL discharging!