Battery health dropping continuously.

At this point I’d say you might want to request a diagnostic. If you can’t make it in it should be possible to do one by phone where it would be run over the Internet and the result would be recorded. The warranty on a replacement battery is 90 days.

disxahh wrote:

How to run it over the internet?

You would need to call in to Apple support wherever you're located. This may not be possible if you're in a country where Apple doesn't directly provide phone support. In the United States the number is 1-800-275-2273.

Contact Apple for support and service - Apple Support

I've only had a diagnostic done in person at an Apple Store, but it was a fairly simple process and I think it's similar over the internet. I had to connect direct to the store's Wi-Fi and then an Apple employee provided a specific URL to enter in Safari, with a specific case number as part of it. Then it would run and come back with a result on the employee's iPad Mini. I believe that a remote one is pretty similar. Some have mentioned it back when iPhone batteries were in high demand and they could reserve a spot in line by doing the diagnostic over the phone first.

Who replaced it and was it a genuine Apple battery?

Specifically Apple doesn't consider it a problem unless it finally dips below that magic 80% number or it goes into an unplanned shutdown. It's also only an estimate.

disxahh wrote:

yes it was a genuine one and replaced by an authorized repair center. So there’s nothing to worry about it anymore or....?

I certainly understand that it seems there's something wrong, or that one should be able to rely on milestones for battery decline. But the only standard that Apple has is 500 cycles and 80% battery health. Or if the battery fails.

Anything in between is considered normal. I've had it decline from 96 to 94 within two weeks, and then to 88% in another two weeks. I can't necessarily tell if it's just the battery health reading catching up to actual battery health or perhaps a steady decline. There can be weird readings. When battery health first came out some people were reporting a reading of 101%. A battery health reading going up isn't unusual. I'm pretty sure if you bring it in and ask that it be replaced on the basis of it being at 94% they're going to say no.

If you're near an Apple Store you can always request a free diagnostic to see if maybe there's something wrong.

disxahh wrote:

Anyway thank you for your help! And could you please tell me best practices for charging my iPhone.

I know there are a lot of different recommendations out there, but I say use you phone and don’t worry about it. If anything were particularly bad then Apple would build it into their battery management system. The only thing I think is critical is that if it ever goes down to 0% and a controlled auto shutdown, be sure to charge it. The one thing that’s well known to kill batteries is letting it go into deep discharge. 0% isn’t the absolute floor, but self discharge can eventually bring the charge level to a point where the battery suffers permanent damage.