mattzulu
Re: iOS 6 iPhone 4s battery drain
Feb 22, 2013 9:11 AM (
in response to Pizza98704)
Pizza while I appreciate your suggestion, and the intent, I must advise you with this battery once you've reached 100% -any time longer on the charger than let's say one hour is actually bad for long term battery life. Full cycle charges however, are beneficial. A full cycle charge is when you allow your phone to drop below 20% and then charge your phone to 100% without interruption. Allowing a maximum of 1 hour past 100% on the charger.
And yes my battery life is still terrible post the most recent update. Apple needs to handle this.
Lot of misinformation above.
First, the lithium ion charge management ic in the iPhone does not allow the battery to continually charge if left connected "beyond one hour". It charges the battery with a modified constant-current/constant-voltage charge curve. It will charge at a constant-current rate of up to 900mAHr (depending on power-source) up until the charge voltage is 4.19v, at which point it maintains constant-voltage 4.19v charge rate. Normal Lithium-ion terminates when the charge current drops to 1/5 of the constant-current rate (900/5 mAHr in this case) but the iPhone has specific disconnects the battery from the charge circuit and allows the phone to be powered by the USB directly. In this state, it will show the battery status as an appliance plug, rather than a lightning bolt (example: http://halo.bungie.org/misc/mid7night_iphone_goodies/BungieHaloTheme3.jpeg). There is no harm in leaving the iPhone connected to external power indefinitely in this state, and in fact, doing so increases battery longevity, since otherwise, the battery would be draining to power the phone, exhausting the finite charge cycles.
Second, full cycle charges are not beneficial for the battery in any way. They are however needed for ensuring that the battery guage reading accurately represents the energy content of the battery by keeping them calibrated to one another, as well as letting the charge IC better know the charge capacity so it can better manage the charge process. Draining the Lithium-ion battery any amount, and charging it up, diminishes a portion of the finite number of useful charge cycles from it (>80% of original battery capacity after 400 cycles, in the case of the 4S). Full charge cycles are not needed, nor beneficial at all for the battery itself. Apple's documentation is purposefully misleading on this, erring on over-simplification in order to get users to perform a single full charge cycle once per month.
Lastly, a full cycle discharge should not be terminated when the battery guage reads 20% or less. It terminates when the iPhone shuts down on it's own. Only by allowing the iPhone to fully depleat on it's own during normal use, will the battery level guage be given the information necessary to recalibrate it's parameters to the battery. Artificially increasing the discharge rate (such as by running a GPS app, game, or some other application that uses many of the on-board radios and devices, in addition to the screen and CPU) undermines the calibration proceedure and will result in inaccurate calibration where the capacity reported will be lower than actual capacity. If during the calibration process, you terminated discharge manually when the phone charge guage indicated <20%, then you have not performed the calibration proceedure, and thus, cannot state whether you have a problem with your battery or not, based on percieved abnormally-fast depletion.