Phone battery health dropped from 99% to 95% in 10 days

Read this support article about iPhone battery and performance to learn about the battery health feature and what is considered normal performance --> iPhone battery and performance - Apple Support

To see the feature go to: Settings > Battery > Battery Health

"A normal battery is designed to retain up to 80% of its original capacity at 500 complete charge cycles when operating under normal conditions. The one-year warranty includes service coverage for a defective battery. If it is out of warranty, Apple offers battery service for a charge." A degraded battery may display the notice: "Your battery’s health is significantly degraded. An Apple Authorized Service Provider can replace the battery to restore full performance and capacity." If it is not at or above 80% "normal", consider contacting Apple about a battery replacement. --> iPhone Battery Replacement - Apple Support

According to the above quoted information, you could be losing almost 2% per month the entire first year before Apple would deem this to be unusual battery behavior and merit a warranty replacement.

Also read:

- Apple’s support article about batteries draining too quickly —> If the battery in your iPhone or iPad drains too quickly - Apple Support

- This post by ASC contributor Lawrence Finch which has a very user-friendly explanation of battery features --> https://discussions.apple.com/thread/254824841?answerId=258988099022#258988099022

Frankly I would pretty much regard that as standard error in the determination unless it keeps on doing that. Kind of like my car's miles per gallon number varying between 37-43 mpg each week. When it dropped to 15mpg one week then I knew something was wrong, and sure enough, the fuel pump was leaking.

It is not likely that an iPhone 13 would have had a 99% Battery Health 10 days ago on the original battery. So that leads to the obvious questions of:

• When was it replaced?
• Who replaced it?
• Did you purchase the phone used?

Also, the battery health will not be updated until the phone is able to charge to 100%. Even when there is a Charge Limit option, the phone will still charge to 100% on occasion to calibrate those setting. If you are manually preventing charging the phone to 100%, then you are likely going to see a larger than expected drop when it has charged to 100%.

The battery on an iPhone 13 is only expected to last for 500 charges cycles, and on average that is about a 1% drop for every 25 charge cycles.

Are you the original owner? If the battery was replaced with non Apple branded battery, the battery might be defective or of poor quality and not performing to the manufacturer’s specifications and standards.

How does an iPhone 13.....which was discontinued in Sept 2014.....have a battery health of 99%? Did you replace the battery in the last month or two? Did you buy a "refurbished phone"?

Things don't add up. Something is not right. We need more details from you.

The battery in a phone that is 14-15 months old would normally be in the 88-90% range at this point.

You bought the phone in June 2025. Since Apple discontinued the iPhone 13 in September of 2025.....if you really did buy a new phone......it sat in a warehouse for 5-6 months before you began to use the phone. That would not have been good for the battery.

The battery in an iPhone is expected to decline at an average rate of about 1% a month. But, that decline is not linear. The battery might go a few months with no drop, then drop 3% the next month. You have been using the phone for about 6 months. The battery health should be at about 94-95% at this point.

You had very good luck for 4-5 months, but the averages have caught up to you. So now, your battery is performing normally. If the battery drops below 80% before June, Apple will probably replace the battery for you at no charge.