Battery dropping to 98 after charging to 100

Your battery is fine. More likely it's related to your line voltage or to minor deviations in the full charge level for your particular battery.

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MacBook and MacBook Pro- Mac reduces processor speed when battery is removed while operating from an A-C adaptor

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Apple Portables- Calibrating your computer's battery for best performance

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How to Calibrate Your Mac, iPhone, or iPad Battery | MacBlend

Here's how the iPhone charge cycle works. First, the "charger" is not a charger; it's a power source. The actual charger is a circuit in the phone. It charges the battery at a fast rate to about 65%, then tapers slowly, and at 90% it slows to a crawl, until it reaches 100%. Then the charge circuit turns of completely. So it will reach 80% in 2 hours, 100% in 3-4 hours. Once it shuts off it monitors the battery drain. When the drain reaches about 4% (96% charge) the charger comes back on and tops up the battery. So if you leave it plugged in all the time it will always be between 96% and 100%. This is normal.

You can "fine tune" the battery gauge by draining the battery all the way down to 1%, then continue using it until it shuts off. Then charge for 4 hours with the wall unit. It's a good idea to do this once a month or so, according to Apple's battery tips.

Larry,

I think you meant to say "draining the battery all the way down to 10%." 1% would seem dangerously low, I think.

Kappy wrote:

Larry,

I think you meant to say "draining the battery all the way down to 10%." 1% would seem dangerously low, I think.

Kappy, actually, no, I meant all the way down until the phone shuts off and does not restart. This is Apple's advice in their battery tips. The secret is that 1% is not 1% of the battery life; it's 1% before the reserve built into the battery protection circuit. The phone shuts off with a fairly substantial charge left in the battery.

Gotcha!! My misunderstanding, so thanks for that infor. 🙂

Kappy, at your level I'm alway hesitant to disagree with you. Your experience greatly exceeds mine. But in this case I at least have a reference 😉

After you charge it up, and it drops a bit, try and restart the phone. A dollar says it will say 100% when you restart it. Not sure why though. Kappy, Finch?

Larry,

I appreciate those kind words. But when I'm wrong, I'm wrong. I trust your knowledge, as well. 😀

I've already told you "what's with it" - IT IS NORMAL BEHAVIOR. And I even explained why.

@Lawrence, i disagree with you about this being a normal behavior. Sometimes my iphone 5s is charged to 100%, even after i unplug it, other times it shows 100%, and drops to 98% as soon as i unplug it. But it goes to 100% if i reboot the phone or i let it go to 97% and plug it back and in 20min it goes up to 100% as it should be. I always charge it for about 10h so why on the earth the charge isn't the same? Why showing 100% if it's 98%?

Because it only updates the display when you turn it on.

Actually the display is updated when you unplug it. I always check the iPhone before i unplug it and it shows 100%, not 98%...

I think the real issue is being discussed here http://forums.imore.com/iphone-5/252275-reboot-show-real-battery-level.html

Reboot to show real battery level.

I bought an iPhone 7 and it does the same thing. It will also continuesly charge with no protection like apple says it has. So to back up all the lies that it's a software issue or my fault. I took my old 5s and updated it. Guess what it's the new software that's casing this because my old phone doesn't do it with the old os. Went to apple 2 times no one understands