iPhone 14 battery health dropped 100% to 86% in 2 months

It is very likely that you bought a used phone. Even if the phone really was "new", it sat in a warehouse somewhere for more than a year.....probably longer.....which would not have been good for the battery.

Tap Settings > General > About and look for Warranty Coverage. What does it say there?

Anything there regarding Parts & Service History? What does it say there?

If you just bought this phone, you bought a used phone and someone boosted the battery health reading. Boosting is a way of falsely tweeking the health reading of the phone to make it a higher value than it actually is.

The IPhone 14 was discontinued a year ago in February 2025. You did not buy a new phone.

Contact whoever you purchased this from and take it up with them.

If this is a phone you already had and just had the battery replaced by a third party repair shop, they put a non-Apple battery in it and it was an inferior product. Take this up with the shop that replaced it.

If Apple replaced it, the contact the Genius Bar and have them diagnose the issue.

Genius Bar Reservation and Apple Support Options - Apple

from your screenshot......Coverage expired in September 2024.

The coverage would have expired a year after the phone was originally sold. That would have been September 2023.

Your phone is now more than 2 years old. I would expect the battery health to be in the 80-82% range at this point.

Did you have a new battery installed in the phone recently? If not, the battery numbers that you are seeing are not real. They have been altered, so it is not possible to know what shape the battery really is in at this point.

Yup, you bought an old, used phone. Where did you buy it from? Talk to them for help.

Did you purchase the device used?

It simply is not likely that a phone discontinued a year ago and first manufactured over 3 years ago would have been showing 100% Battery Health 2 months ago on its original battery. So, then it becomes relevant where you purchased the iPhone. If purchased from a third party, the battery health was probably "boosted" to show an inflated value or the battery had been replaced with a non genuine part.

The iPhone 14 is expected to last 500 charges cycles before the battery health will drop below 80%, so I do not know the charge cycles you have on your battery or if it had been replaced already.

rhoda94 wrote:

I brought it last December 3rd, from its box

I didn’t know they’ve discontinued making new iPhone 14

OK. You. bought a used phone.

When the battery reaches 80%, it needs to be replaced.

Because it's old... or maybe the battery was replaced by an unauthorized shop and they 'tweaked' iOS to falsify the battery health.The iPhone 14 and 14 Plus were discontinued in February of 2025. The 14 Pro and Pro Max were discontinued in September of 2023.

rhoda94 wrote:

I brought it last December 3rd, from its box

I didn’t know they’ve discontinued making new iPhone 14

Even though they were discontinued in2023 you could have possibly found a new unused sealed iphone 14 in 2025, but this was not one, and if it was sold as such you have a case for a full refund.

So it was originally sold in September of 2023. it's almost 2 1/2 years old.