iPhone 6s Plus battery capacity < 90% after 4 months

Philly_Phan wrote:

Lawrence Finch wrote:

So running it down until the phone shuts off, then charging it immediately to 100% will not hurt the battery, and will recalibrate the battery gauge.

At one time Apple made that recommendation but they pulled it.

They dropped it because it was generally no longer necessary; they improved the battery gauge software. But it's still not perfect. If your phone does not charge to 100%, or shuts off above 1%, this is the first thing to do.

Lawrence Finch wrote:

OriginalName022 wrote:

The annoying thing about batteries is this: Draining the battery until your phone shuts off is how you calibrate it. However, every time you do this, you are damaging it a little.

No, you are not damaging it a little. You are not damaging it at all. See my other post.

There are many factors that affect the health of lithium-based batteries beyond cycle count, one of these being depth of discharge. A deeper DoD will accelerate how fast a battery normally decreases in capacity. Saying that it is damaging was probably not entirely correct, but batteries retain a higher capacity when not discharged as deeply. For example, if you charge your phone once it reaches 50% twice a day instead of waiting until it shuts off before charging, it will retain a higher capacity even though the number of charge cycles is the same.

I realize that there is still some left. I was actually being a little simplistic, as so many were recommending draining it so often.

OriginalName022 wrote:

There are many factors that affect the health of lithium-based batteries beyond cycle count, one of these being depth of discharge.

AS I explained, discharging it to zero is not deep discharge. Deep discharge is discharging to zero, then not charging it for a couple of weeks. The phone is designed to not subject the battery to deep discharge by "lying" about the state of charge and shutting down before the battery is discharged to a level that can damage it.

Lawrence Finch wrote:

OriginalName022 wrote:

There are many factors that affect the health of lithium-based batteries beyond cycle count, one of these being depth of discharge.

AS I explained, discharging it to zero is not deep discharge. Deep discharge is discharging to zero, then not charging it for a couple of weeks. The phone is designed to not subject the battery to deep discharge by "lying" about the state of charge and shutting down before the battery is discharged to a level that can damage it.

The concept of DoD still applies. The shallower the discharge, the more cycles you'll get out of a battery. A phone run down to 20% (80% DoD) every day will get fewer charge cycles than a phone run down to 60% (40% DoD) twice a day. It is not practical for a user to worry about this concept too much, but doing a "full discharge" too often will cause a noticeable decrease in battery performance over a shorter period of time.

OriginalName022 wrote:

The concept of DoD still applies. The shallower the discharge, the more cycles you'll get out of a battery. A phone run down to 20% (80% DoD) every day will get fewer charge cycles than a phone run down to 60% (40% DoD) twice a day. It is not practical for a user to worry about this concept too much, but doing a "full discharge" too often will cause a noticeable decrease in battery performance over a shorter period of time.

Please provide a reference that says supports your statement. I've never seen any reference that says that, and I believe it is nonsense.

See http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batterie s

The fact that a SMART standard lithium battery cannot be drained fully because the device shuts off is a function of the international standards on certified SMART technology, not anything special that Apple does. Lithium cells become dangerous to recharge if fully depleted and may swell, burst or overheat and burn.

It is also well known that to maximize the useful life span of a lithium battery, it is optimal to avoid deep cycles (not full discharge, but simple depletion to a charge state well below 50%) and instead charge or partially charge more frequently to cause more shallow discharge/charge cycles. Doing that will significantly extend the useful life of the battery versus frequent deep cycles.

So draining the battery to device auto-shut off does nothing useful at all, with the current state of the capacity tracking software, and it will serve to cause the battery to age more rapidly than it otherwise would If it was just charged or partially charged well before auto-shut down occurred.

Michael Black wrote:

So draining the battery to device auto-shut off does nothing useful at all, with the current state of the capacity tracking software, and it will serve to cause the battery to age more rapidly than it otherwise would.

We have frequent posts that say the iPhone fails to charge to 100% (stops at, say, 98%). And others that say that the phone shuts off at a fairly high SoC, such as 20% or 40%. The advice I have always given is to discharge until the phone shuts off, then charge to 100%. This invariably fixes the problem. So draining the battery to device shut-off does something very useful.

Also, until very recently Apple recommended to perform this cycle on a monthly basis. Was Apple destroying batteries with this advice? Was this an Apple conspiracy to force people to get new phones, or at least get their batteries replaced?

Apple dropped that recommendation over two years ago, not recently. And yes, I imagine their engineers did indeed know that it was not optimal for battery life, but it was necessary to keep the battery level indicator somewhat accurate. Newer SMART technology makes that generally unnecessary.

I'm not trying to be combatative here, but your information on current lithium technology is simply out of date. You are free to advice users as you wish, and I will do the same. I've said my piece and am done here. My goodness, people have developed thin skins around here lately?